Re: [Intel-gfx] [PATCH 1/3] drm/i915: Reject bigjoiner if the pipe doesn't support it

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Jan 21, 2022 at 04:03:09PM +0200, Jani Nikula wrote:
> On Fri, 21 Jan 2022, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Check that our crtc can in fact be the bigjoiner master before
> > we let the modeset proceed with bigjoiner enabled.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index 0964b2403e2d..36e547bd0cbe 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -4102,6 +4102,14 @@ static u8 bigjoiner_pipes(struct drm_i915_private *i915)
> >  		return 0;
> >  }
> >  
> > +static u8 bigjoiner_master_pipes(struct drm_i915_private *i915)
> > +{
> > +	u8 pipes = bigjoiner_pipes(i915);
> > +
> > +	/* last pipe can not be master */
> > +	return pipes & (pipes >> 1);
> > +}
> > +
> >  static bool transcoder_ddi_func_is_enabled(struct drm_i915_private *dev_priv,
> >  					   enum transcoder cpu_transcoder)
> >  {
> > @@ -7600,6 +7608,7 @@ static int intel_atomic_check_bigjoiner(struct intel_atomic_state *state,
> >  					struct intel_crtc_state *old_crtc_state,
> >  					struct intel_crtc_state *new_crtc_state)
> >  {
> > +	struct drm_i915_private *i915 = to_i915(state->base.dev);
> >  	struct intel_crtc_state *slave_crtc_state, *master_crtc_state;
> >  	struct intel_crtc *slave_crtc, *master_crtc;
> >  
> > @@ -7615,6 +7624,13 @@ static int intel_atomic_check_bigjoiner(struct intel_atomic_state *state,
> >  	if (!new_crtc_state->bigjoiner)
> >  		return 0;
> >  
> > +	if ((bigjoiner_master_pipes(i915) & BIT(crtc->pipe)) == 0) {
> 
> Feels like the check should be in
> intel_dsc_get_bigjoiner_{secondary,primary}.

The master pipe is selected by userspace. intel_dsc_get_bigjoiner_primary()
is not relevant here.

side note: A lot of that code really should be moved out of intel_vdsc.c
since we also have the uncompressed joiner to consider. Should probably
do a global s/bigjoiner/joiner/ as well since afaik "bigjoiner" refers
specifically to the compressed joiner.

-- 
Ville Syrjälä
Intel