On Thu, May 24, 2018 at 09:15:37PM +0100, Chris Wilson wrote: > Quoting Chris Wilson (2018-05-24 21:14:23) > > Quoting Ville Syrjala (2018-05-24 20:04:05) > > > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > > > > My ILK seems to generate a spurious PCH underrun with most interlaced > > > HDMI modes. Add a second vblank wait to avoid it. > > > > > > We have seen some spurious PCH underruns still in CI as well, some > > > of which seem to be progressive DP. The logs also point towards some > > > spurious underrins with progressive HDMI on SNB. While I don't have > > > a solid explanation for those let's try to kill all the birds with one > > > stone and always do the double wait. > > > > > > Buzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106387 > > > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > --- > > > drivers/gpu/drm/i915/intel_display.c | 11 +++++++++-- > > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c > > > index 7604fbda0607..b5fa4943372a 100644 > > > --- a/drivers/gpu/drm/i915/intel_display.c > > > +++ b/drivers/gpu/drm/i915/intel_display.c > > > @@ -5528,9 +5528,16 @@ static void ironlake_crtc_enable(struct intel_crtc_state *pipe_config, > > > if (HAS_PCH_CPT(dev_priv)) > > > cpt_verify_modeset(dev, intel_crtc->pipe); > > > > > > - /* Must wait for vblank to avoid spurious PCH FIFO underruns */ > > > - if (intel_crtc->config->has_pch_encoder) > > > + /* > > > + * Must wait for vblank to avoid spurious PCH FIFO underruns. > > > + * And a second vblank wait is needed at least on ILK with > > > + * some interlaced HDMI modes. Let's do the double wait always > > > + * in case there are more corner cases we don't know about. > > > + */ > > > + if (intel_crtc->config->has_pch_encoder) { > > > + intel_wait_for_vblank(dev_priv, pipe); > > > intel_wait_for_vblank(dev_priv, pipe); > > > > The only purpose for the double wait here is for delaying the switching > > on of underrun reporting, right? It doesn't accidentally fix anything > > else? > > E.g. in a multi-crtc setup, that's a big delay between switching on a > pair of pipes. I was testing with one pipe only. So at least it's not meant to do anything else. -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
