Merge branch 'drm-vbl-timestamp' of git://gitorious.org/vsyrjala/linux into drm-next

Here's the vblank timestamp pull request you wanted.

I addressed the few bugs that Mario pointed out and added
the r-bs.

As it has been a while since I made the changes, I gave it a
quick spin on a few different i915 machines. Fortunately
everything still seems to be fine.

* 'drm-vbl-timestamp' of git://gitorious.org/vsyrjala/linux:
  drm/i915: Add a kludge for DSL incrementing too late and ISR not working
  drm/radeon: Move the early vblank IRQ fixup to radeon_get_crtc_scanoutpos()
  drm: Pass 'flags' from the caller to .get_scanout_position()
  drm: Fix vblank timestamping constants for interlaced modes
  drm/i915: Fix scanoutpos calculations for interlaced modes
  drm: Change {pixel,line,frame}dur_ns from s64 to int
  drm: Use crtc_clock in drm_calc_timestamping_constants()
  drm/radeon: Populate crtc_clock in radeon_atom_get_tv_timings()
  drm: Simplify the math in drm_calc_timestamping_constants()
  drm: Improve drm_calc_timestamping_constants() documentation
  drm/i915: Call drm_calc_timestamping_constants() earlier
  drm/i915: Kill hwmode save/restore
  drm: Pass the display mode to drm_calc_vbltimestamp_from_scanoutpos()
  drm: Pass the display mode to drm_calc_timestamping_constants()

10 files changed, 137 insertions, 135 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 01361aba033b..245fe4fa9c9e 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -536,7 +536,7 @@ bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
 	 * are later needed by vblank and swap-completion
 	 * timestamping. They are derived from true hwmode.
 	 */
-	drm_calc_timestamping_constants(crtc);
+	drm_calc_timestamping_constants(crtc, &crtc->hwmode);
 
 	/* FIXME: add subpixel order */
 done:
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index e7de2da57234..c2676b5908d9 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -436,45 +436,41 @@ int drm_control(struct drm_device *dev, void *data,
 }
 
 /**
- * drm_calc_timestamping_constants - 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.
+ * 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)
+void drm_calc_timestamping_constants(struct drm_crtc *crtc,
+				     const struct drm_display_mode *mode)
 {
-	s64 linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0;
-	u64 dotclock;
-
-	/* Dot clock in Hz: */
-	dotclock = (u64) crtc->hwmode.clock * 1000;
-
-	/* Fields of interlaced scanout modes are only half a frame duration.
-	 * Double the dotclock to get half the frame-/line-/pixelduration.
-	 */
-	if (crtc->hwmode.flags & DRM_MODE_FLAG_INTERLACE)
-		dotclock *= 2;
+	int linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0;
+	int dotclock = mode->crtc_clock;
 
 	/* Valid dotclock? */
 	if (dotclock > 0) {
-		int frame_size;
-		/* Convert scanline length in pixels and video dot clock to
-		 * line duration, frame duration and pixel duration in
-		 * nanoseconds:
+		int frame_size = mode->crtc_htotal * mode->crtc_vtotal;
+
+		/*
+		 * Convert scanline length in pixels and video
+		 * dot clock to line duration, frame duration
+		 * and pixel duration in nanoseconds:
 		 */
-		pixeldur_ns = (s64) div64_u64(1000000000, dotclock);
-		linedur_ns  = (s64) div64_u64(((u64) crtc->hwmode.crtc_htotal *
-					      1000000000), dotclock);
-		frame_size = crtc->hwmode.crtc_htotal *
-				crtc->hwmode.crtc_vtotal;
-		framedur_ns = (s64) div64_u64((u64) frame_size * 1000000000,
-					      dotclock);
+		pixeldur_ns = 1000000 / dotclock;
+		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 %d: Can't calculate constants, dotclock = 0!\n",
 			  crtc->base.id);
@@ -484,11 +480,11 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc)
 	crtc->framedur_ns = framedur_ns;
 
 	DRM_DEBUG("crtc %d: hwmode: htotal %d, vtotal %d, vdisplay %d\n",
-		  crtc->base.id, crtc->hwmode.crtc_htotal,
-		  crtc->hwmode.crtc_vtotal, crtc->hwmode.crtc_vdisplay);
+		  crtc->base.id, mode->crtc_htotal,
+		  mode->crtc_vtotal, mode->crtc_vdisplay);
 	DRM_DEBUG("crtc %d: clock %d kHz framedur %d linedur %d, pixeldur %d\n",
-		  crtc->base.id, (int) dotclock/1000, (int) framedur_ns,
-		  (int) linedur_ns, (int) pixeldur_ns);
+		  crtc->base.id, dotclock, framedur_ns,
+		  linedur_ns, pixeldur_ns);
 }
 EXPORT_SYMBOL(drm_calc_timestamping_constants);
 
@@ -521,6 +517,7 @@ EXPORT_SYMBOL(drm_calc_timestamping_constants);
  *         0 = Default.
  *         DRM_CALLED_FROM_VBLIRQ = If function is called from vbl irq handler.
  * @refcrtc: drm_crtc* of crtc which defines scanout timing.
+ * @mode: mode which defines the scanout timings
  *
  * Returns negative value on error, failure or if not supported in current
  * video mode:
@@ -540,14 +537,14 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 					  int *max_error,
 					  struct timeval *vblank_time,
 					  unsigned flags,
-					  struct drm_crtc *refcrtc)
+					  const struct drm_crtc *refcrtc,
+					  const struct drm_display_mode *mode)
 {
 	ktime_t stime, etime, mono_time_offset;
 	struct timeval tv_etime;
-	struct drm_display_mode *mode;
-	int vbl_status, vtotal, vdisplay;
+	int vbl_status;
 	int vpos, hpos, i;
-	s64 framedur_ns, linedur_ns, pixeldur_ns, delta_ns, duration_ns;
+	int framedur_ns, linedur_ns, pixeldur_ns, delta_ns, duration_ns;
 	bool invbl;
 
 	if (crtc < 0 || crtc >= dev->num_crtcs) {
@@ -561,10 +558,6 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 		return -EIO;
 	}
 
-	mode = &refcrtc->hwmode;
-	vtotal = mode->crtc_vtotal;
-	vdisplay = mode->crtc_vdisplay;
-
 	/* Durations of frames, lines, pixels in nanoseconds. */
 	framedur_ns = refcrtc->framedur_ns;
 	linedur_ns  = refcrtc->linedur_ns;
@@ -573,7 +566,7 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 	/* If mode timing undefined, just return as no-op:
 	 * Happens during initial modesetting of a crtc.
 	 */
-	if (vtotal <= 0 || vdisplay <= 0 || framedur_ns == 0) {
+	if (framedur_ns == 0) {
 		DRM_DEBUG("crtc %d: Noop due to uninitialized mode.\n", crtc);
 		return -EAGAIN;
 	}
@@ -590,7 +583,7 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 		 * Get vertical and horizontal scanout position vpos, hpos,
 		 * and bounding timestamps stime, etime, pre/post query.
 		 */
-		vbl_status = dev->driver->get_scanout_position(dev, crtc, &vpos,
+		vbl_status = dev->driver->get_scanout_position(dev, crtc, flags, &vpos,
 							       &hpos, &stime, &etime);
 
 		/*
@@ -611,18 +604,18 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 		duration_ns = ktime_to_ns(etime) - ktime_to_ns(stime);
 
 		/* Accept result with <  max_error nsecs timing uncertainty. */
-		if (duration_ns <= (s64) *max_error)
+		if (duration_ns <= *max_error)
 			break;
 	}
 
 	/* Noisy system timing? */
 	if (i == DRM_TIMESTAMP_MAXRETRIES) {
 		DRM_DEBUG("crtc %d: Noisy timestamp %d us > %d us [%d reps].\n",
-			  crtc, (int) duration_ns/1000, *max_error/1000, i);
+			  crtc, duration_ns/1000, *max_error/1000, i);
 	}
 
 	/* Return upper bound of timestamp precision error. */
-	*max_error = (int) duration_ns;
+	*max_error = duration_ns;
 
 	/* Check if in vblank area:
 	 * vpos is >=0 in video scanout area, but negative
@@ -635,25 +628,7 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 	 * since start of scanout at first display scanline. delta_ns
 	 * can be negative if start of scanout hasn't happened yet.
 	 */
-	delta_ns = (s64) vpos * linedur_ns + (s64) hpos * pixeldur_ns;
-
-	/* Is vpos outside nominal vblank area, but less than
-	 * 1/100 of a frame height away from start of vblank?
-	 * If so, assume this isn't a massively delayed vblank
-	 * interrupt, but a vblank interrupt that fired a few
-	 * microseconds before true start of vblank. Compensate
-	 * by adding a full frame duration to the final timestamp.
-	 * Happens, e.g., on ATI R500, R600.
-	 *
-	 * We only do this if DRM_CALLED_FROM_VBLIRQ.
-	 */
-	if ((flags & DRM_CALLED_FROM_VBLIRQ) && !invbl &&
-	    ((vdisplay - vpos) < vtotal / 100)) {
-		delta_ns = delta_ns - framedur_ns;
-
-		/* Signal this correction as "applied". */
-		vbl_status |= 0x8;
-	}
+	delta_ns = vpos * linedur_ns + hpos * pixeldur_ns;
 
 	if (!drm_timestamp_monotonic)
 		etime = ktime_sub(etime, mono_time_offset);
@@ -673,7 +648,7 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, int crtc,
 		  crtc, (int)vbl_status, hpos, vpos,
 		  (long)tv_etime.tv_sec, (long)tv_etime.tv_usec,
 		  (long)vblank_time->tv_sec, (long)vblank_time->tv_usec,
-		  (int)duration_ns/1000, i);
+		  duration_ns/1000, i);
 
 	vbl_status = DRM_VBLANKTIME_SCANOUTPOS_METHOD;
 	if (invbl)
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 6d11e253218a..17d8fcb1b6f7 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -621,36 +621,15 @@ static u32 gm45_get_vblank_counter(struct drm_device *dev, int pipe)
 #define __raw_i915_read32(dev_priv__, reg__) readl((dev_priv__)->regs + (reg__))
 #define __raw_i915_read16(dev_priv__, reg__) readw((dev_priv__)->regs + (reg__))
 
-static bool intel_pipe_in_vblank_locked(struct drm_device *dev, enum pipe pipe)
+static bool ilk_pipe_in_vblank_locked(struct drm_device *dev, enum pipe pipe)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	uint32_t status;
-	int reg;
 
-	if (IS_VALLEYVIEW(dev)) {
-		status = pipe == PIPE_A ?
-			I915_DISPLAY_PIPE_A_VBLANK_INTERRUPT :
-			I915_DISPLAY_PIPE_B_VBLANK_INTERRUPT;
-
-		reg = VLV_ISR;
-	} else if (IS_GEN2(dev)) {
-		status = pipe == PIPE_A ?
-			I915_DISPLAY_PIPE_A_VBLANK_INTERRUPT :
-			I915_DISPLAY_PIPE_B_VBLANK_INTERRUPT;
-
-		reg = ISR;
-	} else if (INTEL_INFO(dev)->gen < 5) {
-		status = pipe == PIPE_A ?
-			I915_DISPLAY_PIPE_A_VBLANK_INTERRUPT :
-			I915_DISPLAY_PIPE_B_VBLANK_INTERRUPT;
-
-		reg = ISR;
-	} else if (INTEL_INFO(dev)->gen < 7) {
+	if (INTEL_INFO(dev)->gen < 7) {
 		status = pipe == PIPE_A ?
 			DE_PIPEA_VBLANK :
 			DE_PIPEB_VBLANK;
-
-		reg = DEISR;
 	} else {
 		switch (pipe) {
 		default:
@@ -664,18 +643,14 @@ static bool intel_pipe_in_vblank_locked(struct drm_device *dev, enum pipe pipe)
 			status = DE_PIPEC_VBLANK_IVB;
 			break;
 		}
-
-		reg = DEISR;
 	}
 
-	if (IS_GEN2(dev))
-		return __raw_i915_read16(dev_priv, reg) & status;
-	else
-		return __raw_i915_read32(dev_priv, reg) & status;
+	return __raw_i915_read32(dev_priv, DEISR) & status;
 }
 
 static int i915_get_crtc_scanoutpos(struct drm_device *dev, int pipe,
-			     int *vpos, int *hpos, ktime_t *stime, ktime_t *etime)
+				    unsigned int flags, int *vpos, int *hpos,
+				    ktime_t *stime, ktime_t *etime)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];
@@ -698,6 +673,12 @@ static int i915_get_crtc_scanoutpos(struct drm_device *dev, int pipe,
 	vbl_start = mode->crtc_vblank_start;
 	vbl_end = mode->crtc_vblank_end;
 
+	if (mode->flags & DRM_MODE_FLAG_INTERLACE) {
+		vbl_start = DIV_ROUND_UP(vbl_start, 2);
+		vbl_end /= 2;
+		vtotal /= 2;
+	}
+
 	ret |= DRM_SCANOUTPOS_VALID | DRM_SCANOUTPOS_ACCURATE;
 
 	/*
@@ -722,17 +703,42 @@ static int i915_get_crtc_scanoutpos(struct drm_device *dev, int pipe,
 		else
 			position = __raw_i915_read32(dev_priv, PIPEDSL(pipe)) & DSL_LINEMASK_GEN3;
 
-		/*
-		 * The scanline counter increments at the leading edge
-		 * of hsync, ie. it completely misses the active portion
-		 * of the line. Fix up the counter at both edges of vblank
-		 * to get a more accurate picture whether we're in vblank
-		 * or not.
-		 */
-		in_vbl = intel_pipe_in_vblank_locked(dev, pipe);
-		if ((in_vbl && position == vbl_start - 1) ||
-		    (!in_vbl && position == vbl_end - 1))
-			position = (position + 1) % vtotal;
+		if (HAS_PCH_SPLIT(dev)) {
+			/*
+			 * The scanline counter increments at the leading edge
+			 * of hsync, ie. it completely misses the active portion
+			 * of the line. Fix up the counter at both edges of vblank
+			 * to get a more accurate picture whether we're in vblank
+			 * or not.
+			 */
+			in_vbl = ilk_pipe_in_vblank_locked(dev, pipe);
+			if ((in_vbl && position == vbl_start - 1) ||
+			    (!in_vbl && position == vbl_end - 1))
+				position = (position + 1) % vtotal;
+		} else {
+			/*
+			 * ISR vblank status bits don't work the way we'd want
+			 * them to work on non-PCH platforms (for
+			 * ilk_pipe_in_vblank_locked()), and there doesn't
+			 * appear any other way to determine if we're currently
+			 * in vblank.
+			 *
+			 * Instead let's assume that we're already in vblank if
+			 * we got called from the vblank interrupt and the
+			 * scanline counter value indicates that we're on the
+			 * line just prior to vblank start. This should result
+			 * in the correct answer, unless the vblank interrupt
+			 * delivery really got delayed for almost exactly one
+			 * full frame/field.
+			 */
+			if (flags & DRM_CALLED_FROM_VBLIRQ &&
+			    position == vbl_start - 1) {
+				position = (position + 1) % vtotal;
+
+				/* Signal this correction as "applied". */
+				ret |= 0x8;
+			}
+		}
 	} else {
 		/* Have access to pixelcount since start of frame.
 		 * We can split this into vertical and horizontal
@@ -809,7 +815,8 @@ static int i915_get_vblank_timestamp(struct drm_device *dev, int pipe,
 	/* Helper routine in DRM core does all the work: */
 	return drm_calc_vbltimestamp_from_scanoutpos(dev, pipe, max_error,
 						     vblank_time, flags,
-						     crtc);
+						     crtc,
+						     &to_intel_crtc(crtc)->config.adjusted_mode);
 }
 
 static bool intel_hpd_irq_event(struct drm_device *dev,
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e77d4b8856a7..14b024becb91 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9597,21 +9597,19 @@ static int __intel_set_mode(struct drm_crtc *crtc,
 {
 	struct drm_device *dev = crtc->dev;
 	drm_i915_private_t *dev_priv = dev->dev_private;
-	struct drm_display_mode *saved_mode, *saved_hwmode;
+	struct drm_display_mode *saved_mode;
 	struct intel_crtc_config *pipe_config = NULL;
 	struct intel_crtc *intel_crtc;
 	unsigned disable_pipes, prepare_pipes, modeset_pipes;
 	int ret = 0;
 
-	saved_mode = kcalloc(2, sizeof(*saved_mode), GFP_KERNEL);
+	saved_mode = kmalloc(sizeof(*saved_mode), GFP_KERNEL);
 	if (!saved_mode)
 		return -ENOMEM;
-	saved_hwmode = saved_mode + 1;
 
 	intel_modeset_affected_pipes(crtc, &modeset_pipes,
 				     &prepare_pipes, &disable_pipes);
 
-	*saved_hwmode = crtc->hwmode;
 	*saved_mode = crtc->mode;
 
 	/* Hack: Because we don't (yet) support global modeset on multiple
@@ -9662,6 +9660,14 @@ static int __intel_set_mode(struct drm_crtc *crtc,
 		/* mode_set/enable/disable functions rely on a correct pipe
 		 * config. */
 		to_intel_crtc(crtc)->config = *pipe_config;
+
+		/*
+		 * Calculate and store various constants which
+		 * are later needed by vblank and swap-completion
+		 * timestamping. They are derived from true hwmode.
+		 */
+		drm_calc_timestamping_constants(crtc,
+						&pipe_config->adjusted_mode);
 	}
 
 	/* Only after disabling all output pipelines that will be changed can we
@@ -9685,23 +9691,10 @@ static int __intel_set_mode(struct drm_crtc *crtc,
 	for_each_intel_crtc_masked(dev, prepare_pipes, intel_crtc)
 		dev_priv->display.crtc_enable(&intel_crtc->base);
 
-	if (modeset_pipes) {
-		/* Store real post-adjustment hardware mode. */
-		crtc->hwmode = pipe_config->adjusted_mode;
-
-		/* Calculate and store various constants which
-		 * are later needed by vblank and swap-completion
-		 * timestamping. They are derived from true hwmode.
-		 */
-		drm_calc_timestamping_constants(crtc);
-	}
-
 	/* FIXME: add subpixel order */
 done:
-	if (ret && crtc->enabled) {
-		crtc->hwmode = *saved_hwmode;
+	if (ret && crtc->enabled)
 		crtc->mode = *saved_mode;
-	}
 
 out:
 	kfree(pipe_config);
diff --git a/drivers/gpu/drm/radeon/radeon_atombios.c b/drivers/gpu/drm/radeon/radeon_atombios.c
index 00bca1bd5745..f48bd6dc10cd 100644
--- a/drivers/gpu/drm/radeon/radeon_atombios.c
+++ b/drivers/gpu/drm/radeon/radeon_atombios.c
@@ -1799,7 +1799,8 @@ bool radeon_atom_get_tv_timings(struct radeon_device *rdev, int index,
 		if (misc & ATOM_DOUBLE_CLOCK_MODE)
 			mode->flags |= DRM_MODE_FLAG_DBLSCAN;
 
-		mode->clock = le16_to_cpu(tv_info->aModeTimings[index].usPixelClock) * 10;
+		mode->crtc_clock = mode->clock =
+			le16_to_cpu(tv_info->aModeTimings[index].usPixelClock) * 10;
 
 		if (index == 1) {
 			/* PAL timings appear to have wrong values for totals */
@@ -1842,7 +1843,8 @@ bool radeon_atom_get_tv_timings(struct radeon_device *rdev, int index,
 		if (misc & ATOM_DOUBLE_CLOCK_MODE)
 			mode->flags |= DRM_MODE_FLAG_DBLSCAN;
 
-		mode->clock = le16_to_cpu(dtd_timings->usPixClk) * 10;
+		mode->crtc_clock = mode->clock =
+			le16_to_cpu(dtd_timings->usPixClk) * 10;
 		break;
 	}
 	return true;
diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 7ea647b84733..d680608f6f5b 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -306,7 +306,7 @@ void radeon_crtc_handle_flip(struct radeon_device *rdev, int crtc_id)
 	 * to complete in this vblank?
 	 */
 	if (update_pending &&
-	    (DRM_SCANOUTPOS_VALID & radeon_get_crtc_scanoutpos(rdev->ddev, crtc_id,
+	    (DRM_SCANOUTPOS_VALID & radeon_get_crtc_scanoutpos(rdev->ddev, crtc_id, 0,
 							       &vpos, &hpos, NULL, NULL)) &&
 	    ((vpos >= (99 * rdev->mode_info.crtcs[crtc_id]->base.hwmode.crtc_vdisplay)/100) ||
 	     (vpos < 0 && !ASIC_IS_AVIVO(rdev)))) {
@@ -1610,6 +1610,7 @@ bool radeon_crtc_scaling_mode_fixup(struct drm_crtc *crtc,
  *
  * \param dev Device to query.
  * \param crtc Crtc to query.
+ * \param flags Flags from caller (DRM_CALLED_FROM_VBLIRQ or 0).
  * \param *vpos Location where vertical scanout position should be stored.
  * \param *hpos Location where horizontal scanout position should go.
  * \param *stime Target location for timestamp taken immediately before
@@ -1631,8 +1632,8 @@ bool radeon_crtc_scaling_mode_fixup(struct drm_crtc *crtc,
  * unknown small number of scanlines wrt. real scanout position.
  *
  */
-int radeon_get_crtc_scanoutpos(struct drm_device *dev, int crtc, int *vpos, int *hpos,
-			       ktime_t *stime, ktime_t *etime)
+int radeon_get_crtc_scanoutpos(struct drm_device *dev, int crtc, unsigned int flags,
+			       int *vpos, int *hpos, ktime_t *stime, ktime_t *etime)
 {
 	u32 stat_crtc = 0, vbl = 0, position = 0;
 	int vbl_start, vbl_end, vtotal, ret = 0;
@@ -1774,5 +1775,27 @@ int radeon_get_crtc_scanoutpos(struct drm_device *dev, int crtc, int *vpos, int
 	if (in_vbl)
 		ret |= DRM_SCANOUTPOS_INVBL;
 
+	/* Is vpos outside nominal vblank area, but less than
+	 * 1/100 of a frame height away from start of vblank?
+	 * If so, assume this isn't a massively delayed vblank
+	 * interrupt, but a vblank interrupt that fired a few
+	 * microseconds before true start of vblank. Compensate
+	 * by adding a full frame duration to the final timestamp.
+	 * Happens, e.g., on ATI R500, R600.
+	 *
+	 * We only do this if DRM_CALLED_FROM_VBLIRQ.
+	 */
+	if ((flags & DRM_CALLED_FROM_VBLIRQ) && !in_vbl) {
+		vbl_start = rdev->mode_info.crtcs[crtc]->base.hwmode.crtc_vdisplay;
+		vtotal = rdev->mode_info.crtcs[crtc]->base.hwmode.crtc_vtotal;
+
+		if (vbl_start - *vpos < vtotal / 100) {
+			*vpos -= vtotal;
+
+			/* Signal this correction as "applied". */
+			ret |= 0x8;
+		}
+	}
+
 	return ret;
 }
diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
index 67fadcf4590f..1235a78fbba1 100644
--- a/drivers/gpu/drm/radeon/radeon_drv.c
+++ b/drivers/gpu/drm/radeon/radeon_drv.c
@@ -109,6 +109,7 @@ int radeon_gem_object_open(struct drm_gem_object *obj,
 void radeon_gem_object_close(struct drm_gem_object *obj,
 				struct drm_file *file_priv);
 extern int radeon_get_crtc_scanoutpos(struct drm_device *dev, int crtc,
+				      unsigned int flags,
 				      int *vpos, int *hpos, ktime_t *stime,
 				      ktime_t *etime);
 extern const struct drm_ioctl_desc radeon_ioctls_kms[];
diff --git a/drivers/gpu/drm/radeon/radeon_kms.c b/drivers/gpu/drm/radeon/radeon_kms.c
index 9e3af24e1b05..114d1672d616 100644
--- a/drivers/gpu/drm/radeon/radeon_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_kms.c
@@ -719,7 +719,7 @@ int radeon_get_vblank_timestamp_kms(struct drm_device *dev, int crtc,
 	/* Helper routine in DRM core does all the work: */
 	return drm_calc_vbltimestamp_from_scanoutpos(dev, crtc, max_error,
 						     vblank_time, flags,
-						     drmcrtc);
+						     drmcrtc, &drmcrtc->hwmode);
 }
 
 #define KMS_INVALID_IOCTL(name)						\
diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index 7c53fb1cc46d..402dbe32c234 100644
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -801,6 +801,7 @@ extern int radeon_crtc_cursor_move(struct drm_crtc *crtc,
 				   int x, int y);
 
 extern int radeon_get_crtc_scanoutpos(struct drm_device *dev, int crtc,
+				      unsigned int flags,
 				      int *vpos, int *hpos, ktime_t *stime,
 				      ktime_t *etime);
 
diff --git a/drivers/gpu/drm/radeon/radeon_pm.c b/drivers/gpu/drm/radeon/radeon_pm.c
index 4e7f8922ae62..8e8153e471c2 100644
--- a/drivers/gpu/drm/radeon/radeon_pm.c
+++ b/drivers/gpu/drm/radeon/radeon_pm.c
@@ -1486,7 +1486,7 @@ static bool radeon_pm_in_vbl(struct radeon_device *rdev)
 	 */
 	for (crtc = 0; (crtc < rdev->num_crtc) && in_vbl; crtc++) {
 		if (rdev->pm.active_crtcs & (1 << crtc)) {
-			vbl_status = radeon_get_crtc_scanoutpos(rdev->ddev, crtc, &vpos, &hpos, NULL, NULL);
+			vbl_status = radeon_get_crtc_scanoutpos(rdev->ddev, crtc, 0, &vpos, &hpos, NULL, NULL);
 			if ((vbl_status & DRM_SCANOUTPOS_VALID) &&
 			    !(vbl_status & DRM_SCANOUTPOS_INVBL))
 				in_vbl = false;