From 3bb403bf421b5b00366a9041a7edc0a1f6494f5e Mon Sep 17 00:00:00 2001 From: Ville Syrjälä Date: Mon, 14 Sep 2015 22:43:44 +0300 Subject: drm: Stop using linedur_ns and pixeldur_ns for vblank timestamps MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Maarten Lankhorst [danvet: Squash in fixup from Thierry Reding for amdgpu.] Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_irq.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) (limited to 'drivers/gpu/drm/drm_irq.c') diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 6b2fefde25a8..9fab3334eb6b 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -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); -- cgit v1.2.3