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drm: Stop using linedur_ns and pixeldur_ns for vblank timestamps

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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: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
[danvet: Squash in fixup from Thierry Reding for amdgpu.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ville Syrjälä
2015-09-14 22:43:44 +03:00
committed by Daniel Vetter
parent eba1f35dfe
commit 3bb403bf42
11 changed files with 43 additions and 34 deletions
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11
drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
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@@ -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;