/*
* drm_irq.c IRQ and vblank support
*
* \author Rickard E. (Rik) Faith <faith@valinux.com>
* \author Gareth Hughes <gareth@valinux.com>
*/
/*
* Created: Fri Mar 19 14:30:16 1999 by faith@valinux.com
*
* Copyright 1999, 2000 Precision Insight, Inc., Cedar Park, Texas.
* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include <drm/drmP.h>
//#include "drm_trace.h"
#include "drm_internal.h"
//#include <linux/interrupt.h> /* For task queue support */
#include <linux/slab.h>
#include <linux/vgaarb.h>
#include <linux/export.h>
ktime_t ktime_get(void);
static inline ktime_t ktime_get_real(void)
{
return ktime_get();
}
static inline ktime_t ktime_mono_to_real(ktime_t mono)
{
return mono;
}
irqreturn_t device_irq_handler(struct drm_device *dev)
{
return dev->driver->irq_handler(0, dev);
}
/* Access macro for slots in vblank timestamp ringbuffer. */
#define vblanktimestamp(dev, pipe, count) \
((dev)->vblank[pipe].time[(count) % DRM_VBLANKTIME_RBSIZE])
/* Retry timestamp calculation up to 3 times to satisfy
* drm_timestamp_precision before giving up.
*/
#define DRM_TIMESTAMP_MAXRETRIES 3
/* Threshold in nanoseconds for detection of redundant
* vblank irq in drm_handle_vblank(). 1 msec should be ok.
*/
#define DRM_REDUNDANT_VBLIRQ_THRESH_NS 1000000
static bool
drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
struct timeval *tvblank, unsigned flags);
static unsigned int drm_timestamp_precision = 20; /* Default to 20 usecs. */
/*
* Default to use monotonic timestamps for wait-for-vblank and page-flip
* complete events.
*/
unsigned int drm_timestamp_monotonic = 1;
static int drm_vblank_offdelay = 5000; /* Default to 5000 msecs. */
module_param_named(vblankoffdelay, drm_vblank_offdelay, int, 0600);
module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600);
module_param_named(timestamp_monotonic, drm_timestamp_monotonic, int, 0600);
static void store_vblank(struct drm_device *dev, unsigned int pipe,
u32 vblank_count_inc,
struct timeval *t_vblank, u32 last)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
u32 tslot;
assert_spin_locked(&dev->vblank_time_lock);
vblank->last = last;
/* All writers hold the spinlock, but readers are serialized by
* the latching of vblank->count below.
*/
tslot = vblank->count + vblank_count_inc;
vblanktimestamp(dev, pipe, tslot) = *t_vblank;
/*
* vblank timestamp updates are protected on the write side with
* vblank_time_lock, but on the read side done locklessly using a
* sequence-lock on the vblank counter. Ensure correct ordering using
* memory barrriers. We need the barrier both before and also after the
* counter update to synchronize with the next timestamp write.
* The read-side barriers for this are in drm_vblank_count_and_time.
*/
smp_wmb();
vblank->count += vblank_count_inc;
smp_wmb();
}
/**
* drm_reset_vblank_timestamp - reset the last timestamp to the last vblank
* @dev: DRM device
* @pipe: index of CRTC for which to reset the timestamp
*
* Reset the stored timestamp for the current vblank count to correspond
* to the last vblank occurred.
*
* Only to be called from drm_vblank_on().
*
* Note: caller must hold dev->vbl_lock since this reads & writes
* device vblank fields.
*/
static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe)
{
u32 cur_vblank;
bool rc;
struct timeval t_vblank;
int count = DRM_TIMESTAMP_MAXRETRIES;
spin_lock(&dev->vblank_time_lock);
/*
* sample the current counter to avoid random jumps
* when drm_vblank_enable() applies the diff
*/
do {
cur_vblank = dev->driver->get_vblank_counter(dev, pipe);
rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, 0);
} while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) && --count > 0);
/*
* Only reinitialize corresponding vblank timestamp if high-precision query
* available and didn't fail. Otherwise reinitialize delayed at next vblank
* interrupt and assign 0 for now, to mark the vblanktimestamp as invalid.
*/
if (!rc)
t_vblank = (struct timeval) {0, 0};
/*
* +1 to make sure user will never see the same
* vblank counter value before and after a modeset
*/
store_vblank(dev, pipe, 1, &t_vblank, cur_vblank);
spin_unlock(&dev->vblank_time_lock);
}
/**
* drm_update_vblank_count - update the master vblank counter
* @dev: DRM device
* @pipe: counter to update
*
* Call back into the driver to update the appropriate vblank counter
* (specified by @pipe). Deal with wraparound, if it occurred, and
* update the last read value so we can deal with wraparound on the next
* call if necessary.
*
* Only necessary when going from off->on, to account for frames we
* didn't get an interrupt for.
*
* Note: caller must hold dev->vbl_lock since this reads & writes
* device vblank fields.
*/
static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,
unsigned long flags)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
u32 cur_vblank, diff;
bool rc;
struct timeval t_vblank;
int count = DRM_TIMESTAMP_MAXRETRIES;
int framedur_ns = vblank->framedur_ns;
/*
* Interrupts were disabled prior to this call, so deal with counter
* wrap if needed.
* NOTE! It's possible we lost a full dev->max_vblank_count + 1 events
* here if the register is small or we had vblank interrupts off for
* a long time.
*
* We repeat the hardware vblank counter & timestamp query until
* we get consistent results. This to prevent races between gpu
* updating its hardware counter while we are retrieving the
* corresponding vblank timestamp.
*/
do {
cur_vblank = dev->driver->get_vblank_counter(dev, pipe);
rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, flags);
} while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) && --count > 0);
if (dev->max_vblank_count != 0) {
/* trust the hw counter when it's around */
diff = (cur_vblank - vblank->last) & dev->max_vblank_count;
} else if (rc && framedur_ns) {
const struct timeval *t_old;
u64 diff_ns;
t_old = &vblanktimestamp(dev, pipe, vblank->count);
diff_ns = timeval_to_ns(&t_vblank) - timeval_to_ns(t_old);
/*
* Figure out how many vblanks we've missed based
* on the difference in the timestamps and the
* frame/field duration.
*/
diff = DIV_ROUND_CLOSEST_ULL(diff_ns, framedur_ns);
if (diff == 0 && flags & DRM_CALLED_FROM_VBLIRQ)
DRM_DEBUG_VBL("crtc %u: Redundant vblirq ignored."
" diff_ns = %lld, framedur_ns = %d)\n",
pipe, (long long) diff_ns, framedur_ns);
} else {
/* some kind of default for drivers w/o accurate vbl timestamping */
diff = (flags & DRM_CALLED_FROM_VBLIRQ) != 0;
}
DRM_DEBUG_VBL("updating vblank count on crtc %u:"
" current=%u, diff=%u, hw=%u hw_last=%u\n",
pipe, vblank->count, diff, cur_vblank, vblank->last);
if (diff == 0) {
WARN_ON_ONCE(cur_vblank != vblank->last);
return;
}
/*
* Only reinitialize corresponding vblank timestamp if high-precision query
* available and didn't fail, or we were called from the vblank interrupt.
* Otherwise reinitialize delayed at next vblank interrupt and assign 0
* for now, to mark the vblanktimestamp as invalid.
*/
if (!rc && (flags & DRM_CALLED_FROM_VBLIRQ) == 0)
t_vblank = (struct timeval) {0, 0};
store_vblank(dev, pipe, diff, &t_vblank, cur_vblank);
}
/*
* Disable vblank irq's on crtc, make sure that last vblank count
* of hardware and corresponding consistent software vblank counter
* are preserved, even if there are any spurious vblank irq's after
* disable.
*/
static void vblank_disable_and_save(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
unsigned long irqflags;
/* Prevent vblank irq processing while disabling vblank irqs,
* so no updates of timestamps or count can happen after we've
* disabled. Needed to prevent races in case of delayed irq's.
*/
spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
/*
* Only disable vblank interrupts if they're enabled. This avoids
* calling the ->disable_vblank() operation in atomic context with the
* hardware potentially runtime suspended.
*/
if (vblank->enabled) {
dev->driver->disable_vblank(dev, pipe);
vblank->enabled = false;
}
/*
* Always update the count and timestamp to maintain the
* appearance that the counter has been ticking all along until
* this time. This makes the count account for the entire time
* between drm_vblank_on() and drm_vblank_off().
*/
drm_update_vblank_count(dev, pipe, 0);
spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
}
static void vblank_disable_fn(unsigned long arg)
{
struct drm_vblank_crtc *vblank = (void *)arg;
struct drm_device *dev = vblank->dev;
unsigned int pipe = vblank->pipe;
unsigned long irqflags;
if (!dev->vblank_disable_allowed)
return;
spin_lock_irqsave(&dev->vbl_lock, irqflags);
if (atomic_read(&vblank->refcount) == 0 && vblank->enabled) {
DRM_DEBUG("disabling vblank on crtc %u\n", pipe);
vblank_disable_and_save(dev, pipe);
}
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
}
/**
* drm_vblank_cleanup - cleanup vblank support
* @dev: DRM device
*
* This function cleans up any resources allocated in drm_vblank_init.
*/
void drm_vblank_cleanup(struct drm_device *dev)
{
unsigned int pipe;
/* Bail if the driver didn't call drm_vblank_init() */
if (dev->num_crtcs == 0)
return;
for (pipe = 0; pipe < dev->num_crtcs; pipe++) {
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
WARN_ON(vblank->enabled &&
drm_core_check_feature(dev, DRIVER_MODESET));
del_timer_sync(&vblank->disable_timer);
}
kfree(dev->vblank);
dev->num_crtcs = 0;
}
EXPORT_SYMBOL(drm_vblank_cleanup);
/**
* drm_vblank_init - initialize vblank support
* @dev: DRM device
* @num_crtcs: number of CRTCs supported by @dev
*
* This function initializes vblank support for @num_crtcs display pipelines.
*
* Returns:
* Zero on success or a negative error code on failure.
*/
int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
{
int ret = -ENOMEM;
unsigned int i;
spin_lock_init(&dev->vbl_lock);
spin_lock_init(&dev->vblank_time_lock);
dev->num_crtcs = num_crtcs;
dev->vblank = kcalloc(num_crtcs, sizeof(*dev->vblank), GFP_KERNEL);
if (!dev->vblank)
goto err;
for (i = 0; i < num_crtcs; i++) {
struct drm_vblank_crtc *vblank = &dev->vblank[i];
vblank->dev = dev;
vblank->pipe = i;
init_waitqueue_head(&vblank->queue);
setup_timer(&vblank->disable_timer, vblank_disable_fn,
(unsigned long)vblank);
}
DRM_INFO("Supports vblank timestamp caching Rev 2 (21.10.2013).\n");
/* Driver specific high-precision vblank timestamping supported? */
if (dev->driver->get_vblank_timestamp)
DRM_INFO("Driver supports precise vblank timestamp query.\n");
else
DRM_INFO("No driver support for vblank timestamp query.\n");
/* Must have precise timestamping for reliable vblank instant disable */
if (dev->vblank_disable_immediate && !dev->driver->get_vblank_timestamp) {
dev->vblank_disable_immediate = false;
DRM_INFO("Setting vblank_disable_immediate to false because "
"get_vblank_timestamp == NULL\n");
}
dev->vblank_disable_allowed = false;
return 0;
err:
dev->num_crtcs = 0;
return ret;
}
EXPORT_SYMBOL(drm_vblank_init);
/**
* drm_irq_install - install IRQ handler
* @dev: DRM device
* @irq: IRQ number to install the handler for
*
* Initializes the IRQ related data. Installs the handler, calling the driver
* irq_preinstall() and irq_postinstall() functions before and after the
* installation.
*
* This is the simplified helper interface provided for drivers with no special
* needs. Drivers which need to install interrupt handlers for multiple
* interrupts must instead set drm_device->irq_enabled to signal the DRM core
* that vblank interrupts are available.
*
* Returns:
* Zero on success or a negative error code on failure.
*/
int drm_irq_install(struct drm_device *dev, int irq)
{
int ret;
unsigned long sh_flags = 0;
if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
return -EINVAL;
if (irq == 0)
return -EINVAL;
/* Driver must have been initialized */
if (!dev->dev_private)
return -EINVAL;
if (dev->irq_enabled)
return -EBUSY;
dev->irq_enabled = true;
DRM_DEBUG("irq=%d\n", irq);
/* Before installing handler */
if (dev->driver->irq_preinstall)
dev->driver->irq_preinstall(dev);
ret = !AttachIntHandler(irq, device_irq_handler, (u32)dev);
/* After installing handler */
if (dev->driver->irq_postinstall)
ret = dev->driver->irq_postinstall(dev);
if (ret < 0) {
dev->irq_enabled = false;
} else {
dev->irq = irq;
}
u16 cmd = PciRead16(dev->pdev->busnr, dev->pdev->devfn, 4);
cmd&= ~(1<<10);
PciWrite16(dev->pdev->busnr, dev->pdev->devfn, 4, cmd);
return ret;
}
EXPORT_SYMBOL(drm_irq_install);
/**
* drm_calc_timestamping_constants - calculate vblank timestamp constants
* @crtc: drm_crtc whose timestamp constants should be updated.
* @mode: display mode containing the scanout timings
*
* Calculate and store various constants which are later
* needed by vblank and swap-completion timestamping, e.g,
* by drm_calc_vbltimestamp_from_scanoutpos(). They are
* derived from CRTC's true scanout timing, so they take
* things like panel scaling or other adjustments into account.
*/
void drm_calc_timestamping_constants(struct drm_crtc *crtc,
const struct drm_display_mode *mode)
{
struct drm_device *dev = crtc->dev;
unsigned int pipe = drm_crtc_index(crtc);
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
int linedur_ns = 0, framedur_ns = 0;
int dotclock = mode->crtc_clock;
if (!dev->num_crtcs)
return;
if (WARN_ON(pipe >= dev->num_crtcs))
return;
/* Valid dotclock? */
if (dotclock > 0) {
int frame_size = mode->crtc_htotal * mode->crtc_vtotal;
/*
* Convert scanline length in pixels and video
* dot clock to line duration and frame duration
* in nanoseconds:
*/
linedur_ns = div_u64((u64) mode->crtc_htotal * 1000000, dotclock);
framedur_ns = div_u64((u64) frame_size * 1000000, dotclock);
/*
* Fields of interlaced scanout modes are only half a frame duration.
*/
if (mode->flags & DRM_MODE_FLAG_INTERLACE)
framedur_ns /= 2;
} else
DRM_ERROR("crtc %u: Can't calculate constants, dotclock = 0!\n",
crtc->base.id);
vblank->linedur_ns = linedur_ns;
vblank->framedur_ns = framedur_ns;
DRM_DEBUG("crtc %u: hwmode: htotal %d, vtotal %d, vdisplay %d\n",
crtc->base.id, mode->crtc_htotal,
mode->crtc_vtotal, mode->crtc_vdisplay);
DRM_DEBUG("crtc %u: clock %d kHz framedur %d linedur %d\n",
crtc->base.id, dotclock, framedur_ns, linedur_ns);
}
EXPORT_SYMBOL(drm_calc_timestamping_constants);
/**
* drm_calc_vbltimestamp_from_scanoutpos - precise vblank timestamp helper
* @dev: DRM device
* @pipe: index of CRTC whose vblank timestamp to retrieve
* @max_error: Desired maximum allowable error in timestamps (nanosecs)
* On return contains true maximum error of timestamp
* @vblank_time: Pointer to struct timeval which should receive the timestamp
* @flags: Flags to pass to driver:
* 0 = Default,
* DRM_CALLED_FROM_VBLIRQ = If function is called from vbl IRQ handler
* @mode: mode which defines the scanout timings
*
* Implements calculation of exact vblank timestamps from given drm_display_mode
* timings and current video scanout position of a CRTC. This can be called from
* within get_vblank_timestamp() implementation of a kms driver to implement the
* actual timestamping.
*
* Should return timestamps conforming to the OML_sync_control OpenML
* extension specification. The timestamp corresponds to the end of
* the vblank interval, aka start of scanout of topmost-leftmost display
* pixel in the following video frame.
*
* Requires support for optional dev->driver->get_scanout_position()
* in kms driver, plus a bit of setup code to provide a drm_display_mode
* that corresponds to the true scanout timing.
*
* The current implementation only handles standard video modes. It
* returns as no operation if a doublescan or interlaced video mode is
* active. Higher level code is expected to handle this.
*
* Returns:
* Negative value on error, failure or if not supported in current
* video mode:
*
* -EINVAL - Invalid CRTC.
* -EAGAIN - Temporary unavailable, e.g., called before initial modeset.
* -ENOTSUPP - Function not supported in current display mode.
* -EIO - Failed, e.g., due to failed scanout position query.
*
* Returns or'ed positive status flags on success:
*
* DRM_VBLANKTIME_SCANOUTPOS_METHOD - Signal this method used for timestamping.
* DRM_VBLANKTIME_INVBL - Timestamp taken while scanout was in vblank interval.
*
*/
int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
unsigned int pipe,
int *max_error,
struct timeval *vblank_time,
unsigned flags,
const struct drm_display_mode *mode)
{
struct timeval tv_etime;
ktime_t stime, etime;
unsigned int vbl_status;
int ret = DRM_VBLANKTIME_SCANOUTPOS_METHOD;
int vpos, hpos, i;
int delta_ns, duration_ns;
if (pipe >= dev->num_crtcs) {
DRM_ERROR("Invalid crtc %u\n", pipe);
return -EINVAL;
}
/* Scanout position query not supported? Should not happen. */
if (!dev->driver->get_scanout_position) {
DRM_ERROR("Called from driver w/o get_scanout_position()!?\n");
return -EIO;
}
/* If mode timing undefined, just return as no-op:
* Happens during initial modesetting of a crtc.
*/
if (mode->crtc_clock == 0) {
DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n", pipe);
return -EAGAIN;
}
/* Get current scanout position with system timestamp.
* Repeat query up to DRM_TIMESTAMP_MAXRETRIES times
* if single query takes longer than max_error nanoseconds.
*
* This guarantees a tight bound on maximum error if
* code gets preempted or delayed for some reason.
*/
for (i = 0; i < DRM_TIMESTAMP_MAXRETRIES; i++) {
/*
* Get vertical and horizontal scanout position vpos, hpos,
* and bounding timestamps stime, etime, pre/post query.
*/
vbl_status = dev->driver->get_scanout_position(dev, pipe, flags,
&vpos, &hpos,
&stime, &etime,
mode);
/* Return as no-op if scanout query unsupported or failed. */
if (!(vbl_status & DRM_SCANOUTPOS_VALID)) {
DRM_DEBUG("crtc %u : scanoutpos query failed [0x%x].\n",
pipe, vbl_status);
return -EIO;
}
/* Compute uncertainty in timestamp of scanout position query. */
duration_ns = ktime_to_ns(etime) - ktime_to_ns(stime);
/* Accept result with < max_error nsecs timing uncertainty. */
if (duration_ns <= *max_error)
break;
}
/* Noisy system timing? */
if (i == DRM_TIMESTAMP_MAXRETRIES) {
DRM_DEBUG("crtc %u: Noisy timestamp %d us > %d us [%d reps].\n",
pipe, duration_ns/1000, *max_error/1000, i);
}
/* Return upper bound of timestamp precision error. */
*max_error = duration_ns;
/* Check if in vblank area:
* vpos is >=0 in video scanout area, but negative
* within vblank area, counting down the number of lines until
* start of scanout.
*/
if (vbl_status & DRM_SCANOUTPOS_IN_VBLANK)
ret |= DRM_VBLANKTIME_IN_VBLANK;
/* Convert scanout position into elapsed time at raw_time query
* since start of scanout at first display scanline. delta_ns
* can be negative if start of scanout hasn't happened yet.
*/
delta_ns = div_s64(1000000LL * (vpos * mode->crtc_htotal + hpos),
mode->crtc_clock);
if (!drm_timestamp_monotonic)
etime = ktime_mono_to_real(etime);
/* save this only for debugging purposes */
tv_etime = ktime_to_timeval(etime);
/* Subtract time delta from raw timestamp to get final
* vblank_time timestamp for end of vblank.
*/
if (delta_ns < 0)
etime = ktime_add_ns(etime, -delta_ns);
else
etime = ktime_sub_ns(etime, delta_ns);
*vblank_time = ktime_to_timeval(etime);
DRM_DEBUG_VBL("crtc %u : v 0x%x p(%d,%d)@ %ld.%ld -> %ld.%ld [e %d us, %d rep]\n",
pipe, vbl_status, hpos, vpos,
(long)tv_etime.tv_sec, (long)tv_etime.tv_usec,
(long)vblank_time->tv_sec, (long)vblank_time->tv_usec,
duration_ns/1000, i);
return ret;
}
EXPORT_SYMBOL(drm_calc_vbltimestamp_from_scanoutpos);
static struct timeval get_drm_timestamp(void)
{
ktime_t now;
now = drm_timestamp_monotonic ? ktime_get() : ktime_get_real();
return ktime_to_timeval(now);
}
/**
* drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent
* vblank interval
* @dev: DRM device
* @pipe: index of CRTC whose vblank timestamp to retrieve
* @tvblank: Pointer to target struct timeval which should receive the timestamp
* @flags: Flags to pass to driver:
* 0 = Default,
* DRM_CALLED_FROM_VBLIRQ = If function is called from vbl IRQ handler
*
* Fetches the system timestamp corresponding to the time of the most recent
* vblank interval on specified CRTC. May call into kms-driver to
* compute the timestamp with a high-precision GPU specific method.
*
* Returns zero if timestamp originates from uncorrected do_gettimeofday()
* call, i.e., it isn't very precisely locked to the true vblank.
*
* Returns:
* True if timestamp is considered to be very precise, false otherwise.
*/
static bool
drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
struct timeval *tvblank, unsigned flags)
{
int ret;
/* Define requested maximum error on timestamps (nanoseconds). */
int max_error = (int) drm_timestamp_precision * 1000;
/* Query driver if possible and precision timestamping enabled. */
if (dev->driver->get_vblank_timestamp && (max_error > 0)) {
ret = dev->driver->get_vblank_timestamp(dev, pipe, &max_error,
tvblank, flags);
if (ret > 0)
return true;
}
/* GPU high precision timestamp query unsupported or failed.
* Return current monotonic/gettimeofday timestamp as best estimate.
*/
*tvblank = get_drm_timestamp();
return false;
}
/**
* drm_vblank_count - retrieve "cooked" vblank counter value
* @dev: DRM device
* @pipe: index of CRTC for which to retrieve the counter
*
* Fetches the "cooked" vblank count value that represents the number of
* vblank events since the system was booted, including lost events due to
* modesetting activity.
*
* This is the legacy version of drm_crtc_vblank_count().
*
* Returns:
* The software vblank counter.
*/
u32 drm_vblank_count(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
if (WARN_ON(pipe >= dev->num_crtcs))
return 0;
return vblank->count;
}
EXPORT_SYMBOL(drm_vblank_count);
/**
* drm_crtc_vblank_count - retrieve "cooked" vblank counter value
* @crtc: which counter to retrieve
*
* Fetches the "cooked" vblank count value that represents the number of
* vblank events since the system was booted, including lost events due to
* modesetting activity.
*
* This is the native KMS version of drm_vblank_count().
*
* Returns:
* The software vblank counter.
*/
u32 drm_crtc_vblank_count(struct drm_crtc *crtc)
{
return drm_vblank_count(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_vblank_count);
/**
* drm_vblank_count_and_time - retrieve "cooked" vblank counter value and the
* system timestamp corresponding to that vblank counter value.
* @dev: DRM device
* @pipe: index of CRTC whose counter to retrieve
* @vblanktime: Pointer to struct timeval to receive the vblank timestamp.
*
* Fetches the "cooked" vblank count value that represents the number of
* vblank events since the system was booted, including lost events due to
* modesetting activity. Returns corresponding system timestamp of the time
* of the vblank interval that corresponds to the current vblank counter value.
*
* This is the legacy version of drm_crtc_vblank_count_and_time().
*/
u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe,
struct timeval *vblanktime)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
int count = DRM_TIMESTAMP_MAXRETRIES;
u32 cur_vblank;
if (WARN_ON(pipe >= dev->num_crtcs))
return 0;
/*
* Vblank timestamps are read lockless. To ensure consistency the vblank
* counter is rechecked and ordering is ensured using memory barriers.
* This works like a seqlock. The write-side barriers are in store_vblank.
*/
do {
cur_vblank = vblank->count;
smp_rmb();
*vblanktime = vblanktimestamp(dev, pipe, cur_vblank);
smp_rmb();
} while (cur_vblank != vblank->count && --count > 0);
return cur_vblank;
}
EXPORT_SYMBOL(drm_vblank_count_and_time);
/**
* drm_crtc_vblank_count_and_time - retrieve "cooked" vblank counter value
* and the system timestamp corresponding to that vblank counter value
* @crtc: which counter to retrieve
* @vblanktime: Pointer to struct timeval to receive the vblank timestamp.
*
* Fetches the "cooked" vblank count value that represents the number of
* vblank events since the system was booted, including lost events due to
* modesetting activity. Returns corresponding system timestamp of the time
* of the vblank interval that corresponds to the current vblank counter value.
*
* This is the native KMS version of drm_vblank_count_and_time().
*/
u32 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
struct timeval *vblanktime)
{
return drm_vblank_count_and_time(crtc->dev, drm_crtc_index(crtc),
vblanktime);
}
EXPORT_SYMBOL(drm_crtc_vblank_count_and_time);
static void send_vblank_event(struct drm_device *dev,
struct drm_pending_vblank_event *e,
unsigned long seq, struct timeval *now)
{
assert_spin_locked(&dev->event_lock);
e->event.sequence = seq;
e->event.tv_sec = now->tv_sec;
e->event.tv_usec = now->tv_usec;
list_add_tail(&e->base.link,
&e->base.file_priv->event_list);
wake_up_interruptible(&e->base.file_priv->event_wait);
}
/**
* drm_arm_vblank_event - arm vblank event after pageflip
* @dev: DRM device
* @pipe: CRTC index
* @e: the event to prepare to send
*
* A lot of drivers need to generate vblank events for the very next vblank
* interrupt. For example when the page flip interrupt happens when the page
* flip gets armed, but not when it actually executes within the next vblank
* period. This helper function implements exactly the required vblank arming
* behaviour.
*
* Caller must hold event lock. Caller must also hold a vblank reference for
* the event @e, which will be dropped when the next vblank arrives.
*
* This is the legacy version of drm_crtc_arm_vblank_event().
*/
void drm_arm_vblank_event(struct drm_device *dev, unsigned int pipe,
struct drm_pending_vblank_event *e)
{
assert_spin_locked(&dev->event_lock);
e->pipe = pipe;
e->event.sequence = drm_vblank_count(dev, pipe);
list_add_tail(&e->base.link, &dev->vblank_event_list);
}
EXPORT_SYMBOL(drm_arm_vblank_event);
/**
* drm_crtc_arm_vblank_event - arm vblank event after pageflip
* @crtc: the source CRTC of the vblank event
* @e: the event to send
*
* A lot of drivers need to generate vblank events for the very next vblank
* interrupt. For example when the page flip interrupt happens when the page
* flip gets armed, but not when it actually executes within the next vblank
* period. This helper function implements exactly the required vblank arming
* behaviour.
*
* Caller must hold event lock. Caller must also hold a vblank reference for
* the event @e, which will be dropped when the next vblank arrives.
*
* This is the native KMS version of drm_arm_vblank_event().
*/
void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
struct drm_pending_vblank_event *e)
{
drm_arm_vblank_event(crtc->dev, drm_crtc_index(crtc), e);
}
EXPORT_SYMBOL(drm_crtc_arm_vblank_event);
/**
* drm_send_vblank_event - helper to send vblank event after pageflip
* @dev: DRM device
* @pipe: CRTC index
* @e: the event to send
*
* Updates sequence # and timestamp on event, and sends it to userspace.
* Caller must hold event lock.
*
* This is the legacy version of drm_crtc_send_vblank_event().
*/
void drm_send_vblank_event(struct drm_device *dev, unsigned int pipe,
struct drm_pending_vblank_event *e)
{
struct timeval now;
unsigned int seq;
if (dev->num_crtcs > 0) {
seq = drm_vblank_count_and_time(dev, pipe, &now);
} else {
seq = 0;
now = get_drm_timestamp();
}
e->pipe = pipe;
send_vblank_event(dev, e, seq, &now);
}
EXPORT_SYMBOL(drm_send_vblank_event);
/**
* drm_crtc_send_vblank_event - helper to send vblank event after pageflip
* @crtc: the source CRTC of the vblank event
* @e: the event to send
*
* Updates sequence # and timestamp on event, and sends it to userspace.
* Caller must hold event lock.
*
* This is the native KMS version of drm_send_vblank_event().
*/
void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
struct drm_pending_vblank_event *e)
{
drm_send_vblank_event(crtc->dev, drm_crtc_index(crtc), e);
}
EXPORT_SYMBOL(drm_crtc_send_vblank_event);
/**
* drm_vblank_enable - enable the vblank interrupt on a CRTC
* @dev: DRM device
* @pipe: CRTC index
*
* Returns:
* Zero on success or a negative error code on failure.
*/
static int drm_vblank_enable(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
int ret = 0;
assert_spin_locked(&dev->vbl_lock);
spin_lock(&dev->vblank_time_lock);
if (!vblank->enabled) {
/*
* Enable vblank irqs under vblank_time_lock protection.
* All vblank count & timestamp updates are held off
* until we are done reinitializing master counter and
* timestamps. Filtercode in drm_handle_vblank() will
* prevent double-accounting of same vblank interval.
*/
ret = dev->driver->enable_vblank(dev, pipe);
DRM_DEBUG("enabling vblank on crtc %u, ret: %d\n", pipe, ret);
if (ret)
atomic_dec(&vblank->refcount);
else {
vblank->enabled = true;
drm_update_vblank_count(dev, pipe, 0);
}
}
spin_unlock(&dev->vblank_time_lock);
return ret;
}
/**
* drm_vblank_get - get a reference count on vblank events
* @dev: DRM device
* @pipe: index of CRTC to own
*
* Acquire a reference count on vblank events to avoid having them disabled
* while in use.
*
* This is the legacy version of drm_crtc_vblank_get().
*
* Returns:
* Zero on success or a negative error code on failure.
*/
int drm_vblank_get(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
unsigned long irqflags;
int ret = 0;
if (!dev->num_crtcs)
return -EINVAL;
if (WARN_ON(pipe >= dev->num_crtcs))
return -EINVAL;
spin_lock_irqsave(&dev->vbl_lock, irqflags);
/* Going from 0->1 means we have to enable interrupts again */
if (atomic_add_return(1, &vblank->refcount) == 1) {
ret = drm_vblank_enable(dev, pipe);
} else {
if (!vblank->enabled) {
atomic_dec(&vblank->refcount);
ret = -EINVAL;
}
}
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
return ret;
}
EXPORT_SYMBOL(drm_vblank_get);
/**
* drm_crtc_vblank_get - get a reference count on vblank events
* @crtc: which CRTC to own
*
* Acquire a reference count on vblank events to avoid having them disabled
* while in use.
*
* This is the native kms version of drm_vblank_get().
*
* Returns:
* Zero on success or a negative error code on failure.
*/
int drm_crtc_vblank_get(struct drm_crtc *crtc)
{
return drm_vblank_get(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_vblank_get);
/**
* drm_vblank_put - release ownership of vblank events
* @dev: DRM device
* @pipe: index of CRTC to release
*
* Release ownership of a given vblank counter, turning off interrupts
* if possible. Disable interrupts after drm_vblank_offdelay milliseconds.
*
* This is the legacy version of drm_crtc_vblank_put().
*/
void drm_vblank_put(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
if (WARN_ON(pipe >= dev->num_crtcs))
return;
if (WARN_ON(atomic_read(&vblank->refcount) == 0))
return;
/* Last user schedules interrupt disable */
if (atomic_dec_and_test(&vblank->refcount)) {
if (drm_vblank_offdelay == 0)
return;
else
vblank_disable_fn((unsigned long)vblank);
}
}
EXPORT_SYMBOL(drm_vblank_put);
/**
* drm_crtc_vblank_put - give up ownership of vblank events
* @crtc: which counter to give up
*
* Release ownership of a given vblank counter, turning off interrupts
* if possible. Disable interrupts after drm_vblank_offdelay milliseconds.
*
* This is the native kms version of drm_vblank_put().
*/
void drm_crtc_vblank_put(struct drm_crtc *crtc)
{
drm_vblank_put(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_vblank_put);
/**
* drm_wait_one_vblank - wait for one vblank
* @dev: DRM device
* @pipe: CRTC index
*
* This waits for one vblank to pass on @pipe, using the irq driver interfaces.
* It is a failure to call this when the vblank irq for @pipe is disabled, e.g.
* due to lack of driver support or because the crtc is off.
*/
void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
int ret;
u32 last;
if (WARN_ON(pipe >= dev->num_crtcs))
return;
ret = drm_vblank_get(dev, pipe);
if (WARN(ret, "vblank not available on crtc %i, ret=%i\n", pipe, ret))
return;
last = drm_vblank_count(dev, pipe);
ret = wait_event_timeout(vblank->queue,
last != drm_vblank_count(dev, pipe),
msecs_to_jiffies(100));
WARN(ret == 0, "vblank wait timed out on crtc %i\n", pipe);
drm_vblank_put(dev, pipe);
}
EXPORT_SYMBOL(drm_wait_one_vblank);
/**
* drm_crtc_wait_one_vblank - wait for one vblank
* @crtc: DRM crtc
*
* This waits for one vblank to pass on @crtc, using the irq driver interfaces.
* It is a failure to call this when the vblank irq for @crtc is disabled, e.g.
* due to lack of driver support or because the crtc is off.
*/
void drm_crtc_wait_one_vblank(struct drm_crtc *crtc)
{
drm_wait_one_vblank(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_wait_one_vblank);
/**
* drm_vblank_off - disable vblank events on a CRTC
* @dev: DRM device
* @pipe: CRTC index
*
* Drivers can use this function to shut down the vblank interrupt handling when
* disabling a crtc. This function ensures that the latest vblank frame count is
* stored so that drm_vblank_on() can restore it again.
*
* Drivers must use this function when the hardware vblank counter can get
* reset, e.g. when suspending.
*
* This is the legacy version of drm_crtc_vblank_off().
*/
void drm_vblank_off(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
struct drm_pending_vblank_event *e, *t;
struct timeval now;
unsigned long irqflags;
unsigned int seq;
if (WARN_ON(pipe >= dev->num_crtcs))
return;
spin_lock_irqsave(&dev->event_lock, irqflags);
spin_lock(&dev->vbl_lock);
vblank_disable_and_save(dev, pipe);
wake_up(&vblank->queue);
/*
* Prevent subsequent drm_vblank_get() from re-enabling
* the vblank interrupt by bumping the refcount.
*/
if (!vblank->inmodeset) {
atomic_inc(&vblank->refcount);
vblank->inmodeset = 1;
}
spin_unlock(&dev->vbl_lock);
/* Send any queued vblank events, lest the natives grow disquiet */
seq = drm_vblank_count_and_time(dev, pipe, &now);
list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
if (e->pipe != pipe)
continue;
DRM_DEBUG("Sending premature vblank event on disable: "
"wanted %d, current %d\n",
e->event.sequence, seq);
list_del(&e->base.link);
drm_vblank_put(dev, pipe);
send_vblank_event(dev, e, seq, &now);
}
spin_unlock_irqrestore(&dev->event_lock, irqflags);
}
EXPORT_SYMBOL(drm_vblank_off);
/**
* drm_crtc_vblank_off - disable vblank events on a CRTC
* @crtc: CRTC in question
*
* Drivers can use this function to shut down the vblank interrupt handling when
* disabling a crtc. This function ensures that the latest vblank frame count is
* stored so that drm_vblank_on can restore it again.
*
* Drivers must use this function when the hardware vblank counter can get
* reset, e.g. when suspending.
*
* This is the native kms version of drm_vblank_off().
*/
void drm_crtc_vblank_off(struct drm_crtc *crtc)
{
drm_vblank_off(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_vblank_off);
/**
* drm_crtc_vblank_reset - reset vblank state to off on a CRTC
* @crtc: CRTC in question
*
* Drivers can use this function to reset the vblank state to off at load time.
* Drivers should use this together with the drm_crtc_vblank_off() and
* drm_crtc_vblank_on() functions. The difference compared to
* drm_crtc_vblank_off() is that this function doesn't save the vblank counter
* and hence doesn't need to call any driver hooks.
*/
void drm_crtc_vblank_reset(struct drm_crtc *crtc)
{
struct drm_device *dev = crtc->dev;
unsigned long irqflags;
unsigned int pipe = drm_crtc_index(crtc);
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
spin_lock_irqsave(&dev->vbl_lock, irqflags);
/*
* Prevent subsequent drm_vblank_get() from enabling the vblank
* interrupt by bumping the refcount.
*/
if (!vblank->inmodeset) {
atomic_inc(&vblank->refcount);
vblank->inmodeset = 1;
}
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
WARN_ON(!list_empty(&dev->vblank_event_list));
}
EXPORT_SYMBOL(drm_crtc_vblank_reset);
/**
* drm_vblank_on - enable vblank events on a CRTC
* @dev: DRM device
* @pipe: CRTC index
*
* This functions restores the vblank interrupt state captured with
* drm_vblank_off() again. Note that calls to drm_vblank_on() and
* drm_vblank_off() can be unbalanced and so can also be unconditionally called
* in driver load code to reflect the current hardware state of the crtc.
*
* This is the legacy version of drm_crtc_vblank_on().
*/
void drm_vblank_on(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
unsigned long irqflags;
if (WARN_ON(pipe >= dev->num_crtcs))
return;
spin_lock_irqsave(&dev->vbl_lock, irqflags);
/* Drop our private "prevent drm_vblank_get" refcount */
if (vblank->inmodeset) {
atomic_dec(&vblank->refcount);
vblank->inmodeset = 0;
}
drm_reset_vblank_timestamp(dev, pipe);
/*
* re-enable interrupts if there are users left, or the
* user wishes vblank interrupts to be enabled all the time.
*/
if (atomic_read(&vblank->refcount) != 0 ||
(!dev->vblank_disable_immediate && drm_vblank_offdelay == 0))
WARN_ON(drm_vblank_enable(dev, pipe));
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
}
EXPORT_SYMBOL(drm_vblank_on);
/**
* drm_crtc_vblank_on - enable vblank events on a CRTC
* @crtc: CRTC in question
*
* This functions restores the vblank interrupt state captured with
* drm_vblank_off() again. Note that calls to drm_vblank_on() and
* drm_vblank_off() can be unbalanced and so can also be unconditionally called
* in driver load code to reflect the current hardware state of the crtc.
*
* This is the native kms version of drm_vblank_on().
*/
void drm_crtc_vblank_on(struct drm_crtc *crtc)
{
drm_vblank_on(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_vblank_on);
/**
* drm_vblank_pre_modeset - account for vblanks across mode sets
* @dev: DRM device
* @pipe: CRTC index
*
* Account for vblank events across mode setting events, which will likely
* reset the hardware frame counter.
*
* This is done by grabbing a temporary vblank reference to ensure that the
* vblank interrupt keeps running across the modeset sequence. With this the
* software-side vblank frame counting will ensure that there are no jumps or
* discontinuities.
*
* Unfortunately this approach is racy and also doesn't work when the vblank
* interrupt stops running, e.g. across system suspend resume. It is therefore
* highly recommended that drivers use the newer drm_vblank_off() and
* drm_vblank_on() instead. drm_vblank_pre_modeset() only works correctly when
* using "cooked" software vblank frame counters and not relying on any hardware
* counters.
*
* Drivers must call drm_vblank_post_modeset() when re-enabling the same crtc
* again.
*/
void drm_vblank_pre_modeset(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
/* vblank is not initialized (IRQ not installed ?), or has been freed */
if (!dev->num_crtcs)
return;
if (WARN_ON(pipe >= dev->num_crtcs))
return;
/*
* To avoid all the problems that might happen if interrupts
* were enabled/disabled around or between these calls, we just
* have the kernel take a reference on the CRTC (just once though
* to avoid corrupting the count if multiple, mismatch calls occur),
* so that interrupts remain enabled in the interim.
*/
if (!vblank->inmodeset) {
vblank->inmodeset = 0x1;
if (drm_vblank_get(dev, pipe) == 0)
vblank->inmodeset |= 0x2;
}
}
EXPORT_SYMBOL(drm_vblank_pre_modeset);
/**
* drm_vblank_post_modeset - undo drm_vblank_pre_modeset changes
* @dev: DRM device
* @pipe: CRTC index
*
* This function again drops the temporary vblank reference acquired in
* drm_vblank_pre_modeset.
*/
void drm_vblank_post_modeset(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
unsigned long irqflags;
/* vblank is not initialized (IRQ not installed ?), or has been freed */
if (!dev->num_crtcs)
return;
if (WARN_ON(pipe >= dev->num_crtcs))
return;
if (vblank->inmodeset) {
spin_lock_irqsave(&dev->vbl_lock, irqflags);
dev->vblank_disable_allowed = true;
spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
if (vblank->inmodeset & 0x2)
drm_vblank_put(dev, pipe);
vblank->inmodeset = 0;
}
}
EXPORT_SYMBOL(drm_vblank_post_modeset);
static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
{
struct drm_pending_vblank_event *e, *t;
struct timeval now;
unsigned int seq;
assert_spin_locked(&dev->event_lock);
seq = drm_vblank_count_and_time(dev, pipe, &now);
list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
if (e->pipe != pipe)
continue;
if ((seq - e->event.sequence) > (1<<23))
continue;
DRM_DEBUG("vblank event on %d, current %d\n",
e->event.sequence, seq);
list_del(&e->base.link);
drm_vblank_put(dev, pipe);
// send_vblank_event(dev, e, seq, &now);
}
}
/**
* drm_handle_vblank - handle a vblank event
* @dev: DRM device
* @pipe: index of CRTC where this event occurred
*
* Drivers should call this routine in their vblank interrupt handlers to
* update the vblank counter and send any signals that may be pending.
*
* This is the legacy version of drm_crtc_handle_vblank().
*/
bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
unsigned long irqflags;
if (WARN_ON_ONCE(!dev->num_crtcs))
return false;
if (WARN_ON(pipe >= dev->num_crtcs))
return false;
spin_lock_irqsave(&dev->event_lock, irqflags);
/* Need timestamp lock to prevent concurrent execution with
* vblank enable/disable, as this would cause inconsistent
* or corrupted timestamps and vblank counts.
*/
spin_lock(&dev->vblank_time_lock);
/* Vblank irq handling disabled. Nothing to do. */
if (!vblank->enabled) {
spin_unlock(&dev->vblank_time_lock);
spin_unlock_irqrestore(&dev->event_lock, irqflags);
return false;
}
drm_update_vblank_count(dev, pipe, DRM_CALLED_FROM_VBLIRQ);
spin_unlock(&dev->vblank_time_lock);
wake_up(&vblank->queue);
drm_handle_vblank_events(dev, pipe);
spin_unlock_irqrestore(&dev->event_lock, irqflags);
return true;
}
EXPORT_SYMBOL(drm_handle_vblank);
/**
* drm_crtc_handle_vblank - handle a vblank event
* @crtc: where this event occurred
*
* Drivers should call this routine in their vblank interrupt handlers to
* update the vblank counter and send any signals that may be pending.
*
* This is the native KMS version of drm_handle_vblank().
*
* Returns:
* True if the event was successfully handled, false on failure.
*/
bool drm_crtc_handle_vblank(struct drm_crtc *crtc)
{
return drm_handle_vblank(crtc->dev, drm_crtc_index(crtc));
}
EXPORT_SYMBOL(drm_crtc_handle_vblank);
/**
* drm_vblank_no_hw_counter - "No hw counter" implementation of .get_vblank_counter()
* @dev: DRM device
* @pipe: CRTC for which to read the counter
*
* Drivers can plug this into the .get_vblank_counter() function if
* there is no useable hardware frame counter available.
*
* Returns:
* 0
*/
u32 drm_vblank_no_hw_counter(struct drm_device *dev, unsigned int pipe)
{
return 0;
}
EXPORT_SYMBOL(drm_vblank_no_hw_counter);
u64 div64_u64(u64 dividend, u64 divisor)
{
u32 high, d;
high = divisor >> 32;
if (high) {
unsigned int shift = fls(high);
d = divisor >> shift;
dividend >>= shift;
} else
d = divisor;
return div_u64(dividend, d);
}