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/*

 * drm_irq.c IRQ and vblank support

 *

 * \author Rickard E. (Rik) Faith 

 * \author Gareth Hughes 

 */

/*

 * 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 

//#include "drm_trace.h"

#include "drm_internal.h"

//#include    /* For task queue support */

#include 

#include 

#include 

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;

	}

	/*

	 * Within a drm_vblank_pre_modeset - drm_vblank_post_modeset

	 * interval? If so then vblank irqs keep running and it will likely

	 * happen that the hardware vblank counter is not trustworthy as it

	 * might reset at some point in that interval and vblank timestamps

	 * are not trustworthy either in that interval. Iow. this can result

	 * in a bogus diff >> 1 which must be avoided as it would cause

	 * random large forward jumps of the software vblank counter.

	 */

	if (diff > 1 && (vblank->inmodeset & 0x2)) {

		DRM_DEBUG_VBL("clamping vblank bump to 1 on crtc %u: diffr=%u"

			      " due to pre-modeset.\n", pipe, diff);

		diff = 1;

	}

	/*

	 * FIMXE: Need to replace this hack with proper seqlocks.

	 *

	 * Restrict the bump of the software vblank counter to a safe maximum

	 * value of +1 whenever there is the possibility that concurrent readers

	 * of vblank timestamps could be active at the moment, as the current

	 * implementation of the timestamp caching and updating is not safe

	 * against concurrent readers for calls to store_vblank() with a bump

	 * of anything but +1. A bump != 1 would very likely return corrupted

	 * timestamps to userspace, because the same slot in the cache could

	 * be concurrently written by store_vblank() and read by one of those

	 * readers without the read-retry logic detecting the collision.

	 *

	 * Concurrent readers can exist when we are called from the

	 * drm_vblank_off() or drm_vblank_on() functions and other non-vblank-

	 * irq callers. However, all those calls to us are happening with the

	 * vbl_lock locked to prevent drm_vblank_get(), so the vblank refcount

	 * can't increase while we are executing. Therefore a zero refcount at

	 * this point is safe for arbitrary counter bumps if we are called

	 * outside vblank irq, a non-zero count is not 100% safe. Unfortunately

	 * we must also accept a refcount of 1, as whenever we are called from

	 * drm_vblank_get() -> drm_vblank_enable() the refcount will be 1 and

	 * we must let that one pass through in order to not lose vblank counts

	 * during vblank irq off - which would completely defeat the whole

	 * point of this routine.

	 *

	 * Whenever we are called from vblank irq, we have to assume concurrent

	 * readers exist or can show up any time during our execution, even if

	 * the refcount is currently zero, as vblank irqs are usually only

	 * enabled due to the presence of readers, and because when we are called

	 * from vblank irq we can't hold the vbl_lock to protect us from sudden

	 * bumps in vblank refcount. Therefore also restrict bumps to +1 when

	 * called from vblank irq.

	 */

	if ((diff > 1) && (atomic_read(&vblank->refcount) > 1 ||

	    (flags & DRM_CALLED_FROM_VBLIRQ))) {

		DRM_DEBUG_VBL("clamping vblank bump to 1 on crtc %u: diffr=%u "

			      "refcount %u, vblirq %u\n", pipe, diff,

			      atomic_read(&vblank->refcount),

			      (flags & DRM_CALLED_FROM_VBLIRQ) != 0);

		diff = 1;

	}

	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