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: 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>
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 6b2fefd..9fab333 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -694,12 +694,11 @@
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 @@
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 @@
* 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 @@
* 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);