Commit 3bb403bf authored by Ville Syrjälä's avatar Ville Syrjälä Committed by Daniel Vetter
Browse files

drm: Stop using linedur_ns and pixeldur_ns for vblank timestamps 



linedur_ns, and especially pixeldur_ns are becoming rather inaccurate
to be used for the vblank timestamp correction. With 4k@60 the pixel
duration is already below 2ns, so the amount of error due to the
truncation to nanoseconds is introducing quite a bit of error.

We can avoid such problems if we instead calculate the timestamp
delta_ns directly from the dislay timings, avoiding the use of
these intermediate truncated values.

Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
[danvet: Squash in fixup from Thierry Reding for amdgpu.]
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent eba1f35d

drivers/gpu/drm/amd/amdgpu/amdgpu_display.c

+6 −5
Original line number Diff line number Diff line
@@ -745,7 +745,8 @@ bool amdgpu_crtc_scaling_mode_fixup(struct drm_crtc *crtc, 
 *

 */

int amdgpu_get_crtc_scanoutpos(struct drm_device *dev, int crtc, unsigned int flags,

			       int *vpos, int *hpos, ktime_t *stime, ktime_t *etime)

			       int *vpos, int *hpos, ktime_t *stime, ktime_t *etime,

			       const struct drm_display_mode *mode)

{

	u32 vbl = 0, position = 0;

	int vbl_start, vbl_end, vtotal, ret = 0;
@@ -781,7 +782,7 @@ int amdgpu_get_crtc_scanoutpos(struct drm_device *dev, int crtc, unsigned int fl 
	}

	else {

		/* No: Fake something reasonable which gives at least ok results. */

		vbl_start = adev->mode_info.crtcs[crtc]->base.hwmode.crtc_vdisplay;

		vbl_start = mode->crtc_vdisplay;

		vbl_end = 0;

	}
@@ -797,7 +798,7 @@ int amdgpu_get_crtc_scanoutpos(struct drm_device *dev, int crtc, unsigned int fl 


	/* Inside "upper part" of vblank area? Apply corrective offset if so: */

	if (in_vbl && (*vpos >= vbl_start)) {

		vtotal = adev->mode_info.crtcs[crtc]->base.hwmode.crtc_vtotal;

		vtotal = mode->crtc_vtotal;

		*vpos = *vpos - vtotal;

	}
@@ -819,8 +820,8 @@ int amdgpu_get_crtc_scanoutpos(struct drm_device *dev, int crtc, unsigned int fl 
	 * We only do this if DRM_CALLED_FROM_VBLIRQ.

	 */

	if ((flags & DRM_CALLED_FROM_VBLIRQ) && !in_vbl) {

		vbl_start = adev->mode_info.crtcs[crtc]->base.hwmode.crtc_vdisplay;

		vtotal = adev->mode_info.crtcs[crtc]->base.hwmode.crtc_vtotal;

		vbl_start = mode->crtc_vdisplay;

		vtotal = mode->crtc_vtotal;



		if (vbl_start - *vpos < vtotal / 100) {

			*vpos -= vtotal;

drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h

+2 −1
Original line number Diff line number Diff line
@@ -543,7 +543,8 @@ void amdgpu_encoder_set_active_device(struct drm_encoder *encoder); 
int amdgpu_get_crtc_scanoutpos(struct drm_device *dev, int crtc,

				      unsigned int flags,

				      int *vpos, int *hpos, ktime_t *stime,

				      ktime_t *etime);

				      ktime_t *etime,

				      const struct drm_display_mode *mode);



int amdgpu_framebuffer_init(struct drm_device *dev,

			     struct amdgpu_framebuffer *rfb,

drivers/gpu/drm/drm_irq.c

+8 −11
Original line number Diff line number Diff line
@@ -694,12 +694,11 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, 
					  unsigned flags,

					  const struct drm_display_mode *mode)

{

	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];

	struct timeval tv_etime;

	ktime_t stime, etime;

	int vbl_status;

	int vpos, hpos, i;

	int framedur_ns, linedur_ns, pixeldur_ns, delta_ns, duration_ns;

	int delta_ns, duration_ns;

	bool invbl;



	if (pipe >= dev->num_crtcs) {
@@ -713,15 +712,10 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, 
		return -EIO;

	}



	/* Durations of frames, lines, pixels in nanoseconds. */

	framedur_ns = vblank->framedur_ns;

	linedur_ns  = vblank->linedur_ns;

	pixeldur_ns = vblank->pixeldur_ns;



	/* If mode timing undefined, just return as no-op:

	 * Happens during initial modesetting of a crtc.

	 */

	if (framedur_ns == 0) {

	if (mode->crtc_clock == 0) {

		DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n", pipe);

		return -EAGAIN;

	}
@@ -738,8 +732,10 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, 
		 * 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);

		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)) {
@@ -776,7 +772,8 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, 
	 * since start of scanout at first display scanline. delta_ns

	 * can be negative if start of scanout hasn't happened yet.

	 */

	delta_ns = vpos * linedur_ns + hpos * pixeldur_ns;

	delta_ns = div_s64(1000000LL * (vpos * mode->crtc_htotal + hpos),

			   mode->crtc_clock);



	if (!drm_timestamp_monotonic)

		etime = ktime_mono_to_real(etime);

drivers/gpu/drm/i915/i915_irq.c

+2 −2
Original line number Diff line number Diff line
@@ -648,12 +648,12 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc) 


static int i915_get_crtc_scanoutpos(struct drm_device *dev, int pipe,

				    unsigned int flags, int *vpos, int *hpos,

				    ktime_t *stime, ktime_t *etime)

				    ktime_t *stime, ktime_t *etime,

				    const struct drm_display_mode *mode)

{

	struct drm_i915_private *dev_priv = dev->dev_private;

	struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];

	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);

	const struct drm_display_mode *mode = &intel_crtc->base.hwmode;

	int position;

	int vbl_start, vbl_end, hsync_start, htotal, vtotal;

	bool in_vbl = true;

drivers/gpu/drm/nouveau/nouveau_display.c

+2 −1
Original line number Diff line number Diff line
@@ -133,7 +133,8 @@ nouveau_display_scanoutpos_head(struct drm_crtc *crtc, int *vpos, int *hpos, 


int

nouveau_display_scanoutpos(struct drm_device *dev, int head, unsigned int flags,

			   int *vpos, int *hpos, ktime_t *stime, ktime_t *etime)

			   int *vpos, int *hpos, ktime_t *stime, ktime_t *etime,

			   const struct drm_display_mode *mode)

{

	struct drm_crtc *crtc;

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