[Intel-gfx] [PATCH 4/6] drm/i915: check for audio and infoframe changes across mode sets v2

[Chris Wilson]

On Mon, Dec 01, 2014 at 08:04:30AM -0800, Jesse Barnes wrote:
> On Mon, 01 Dec 2014 12:25:45 +0200
> Jani Nikula <jani.nikula at linux.intel.com> wrote:
> 
> > On Thu, 06 Nov 2014, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> > > If these change (e.g. after a modeset following a fastboot), we need to
> > > do a full mode set.
> > >
> > > v2:
> > >   - put under pipe_config check so we don't deref a null state (Jesse)
> > >
> > > Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
> > > ---
> > >  drivers/gpu/drm/i915/intel_display.c | 12 +++++++++++-
> > >  1 file changed, 11 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index cb96f11..c86eee6 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -11230,8 +11230,18 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
> > >  						   &modeset_pipes,
> > >  						   &prepare_pipes,
> > >  						   &disable_pipes);
> > > -	if (IS_ERR(pipe_config))
> > > +	if (IS_ERR(pipe_config)) {
> > >  		goto fail;
> > > +	} else if (pipe_config) {
> > > +		if (to_intel_crtc(set->crtc)->new_config->has_audio !=
> > > +		    to_intel_crtc(set->crtc)->config.has_audio)
> > > +			config->mode_changed = true;
> > > +
> > > +		/* Force mode sets for any infoframe stuff */
> > > +		if (to_intel_crtc(set->crtc)->new_config->has_infoframe ||
> > > +		    to_intel_crtc(set->crtc)->config.has_infoframe)
> > 
> > Jesse, is "||" correct here? This is bound to force a lot of mode sets.
> > 
> > See https://bugs.freedesktop.org/show_bug.cgi?id=86683
> 
> Yeah, we talked about it on IRC.  I was being extra conservative here,
> since we don't yet have code to analyze whether we need a full mode set
> due to something that will require an infoframe change.  Currently, the
> only way for us to write a new infoframe is through a mode set, and the
> old code would just happen to do a mode set most of the time we wanted
> it to (i.e. when the mode timings changed), but I don't think we'd ever
> thought of the implications of infoframe changes for stuff that doesn't
> require a mode set.
> 
> We could drop this hunk and continue to play it fast & loose, but what
> we really need here is a fuller check about whether we need a mode set
> due to requiring an infoframe change, which means pulling them apart a
> bit.

We need to be conservative. If we spot extraneous modesets in the wild,
we will be motivated to fix it. As a compromise, if you include a

DRM_DEBUG_KMS("infoframes detected - forcing full modeset\n")

that should be sufficient clue for us to pick up the thread again later.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre