Re: [Intel-gfx] [PATCH 3/3] drm/i915: Mark FBC B gone if pipe B is gone

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

On Thu, Sep 22, 2022 at 11:51:16AM +0300, Jani Nikula wrote:
> On Thu, 22 Sep 2022, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> > On Thu, Sep 22, 2022 at 11:18:55AM +0300, Luca Coelho wrote:
> >> On Fri, 2022-09-16 at 19:52 +0300, Ville Syrjala wrote:
> >> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> > 
> >> > If pipe B is fused off we also shouldn't have FBC B.
> >> > 
> >> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> > ---
> >> >  drivers/gpu/drm/i915/intel_device_info.c | 1 +
> >> >  1 file changed, 1 insertion(+)
> >> > 
> >> > diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c
> >> > index 1434dc33cf49..fbefebc023f1 100644
> >> > --- a/drivers/gpu/drm/i915/intel_device_info.c
> >> > +++ b/drivers/gpu/drm/i915/intel_device_info.c
> >> > @@ -394,6 +394,7 @@ void intel_device_info_runtime_init(struct drm_i915_private *dev_priv)
> >> >  		if (dfsm & SKL_DFSM_PIPE_B_DISABLE) {
> >> >  			runtime->pipe_mask &= ~BIT(PIPE_B);
> >> >  			runtime->cpu_transcoder_mask &= ~BIT(TRANSCODER_B);
> >> > +			runtime->fbc_mask &= ~BIT(INTEL_FBC_B);
> >> >  		}
> >> >  		if (dfsm & SKL_DFSM_PIPE_C_DISABLE) {
> >> >  			runtime->pipe_mask &= ~BIT(PIPE_C);
> >> 
> >> I don't know (yet) what exactly this does, but it makes sense if you
> >> think of consistency: we already do that for PIPE_A.
> >
> > It's basically saying the entire pipe is fused off, so anything
> > living inside that pipe should also be fused off.
> >
> >> 
> >> But what about PIPE_C and PIPE_D? Wouldn't it make sense to do the same
> >> thing for them as well?
> >
> > There is no FBC engine on those pipes (we don't even have
> > the INTEL_FBC_C+ enum values defined), at least for now.
> 
> A future proof way would be to add
> 
> 	runtime->fbc_mask &= runtime->pipe_mask;

Dunno if I entirely like the extra assumption that the enums match.
Also would need to make sure we don't accidentally screw up any
old platforms where FBC is not tied to a specific pipe, but I
guess we should never have pipe A fused off on those w/o
the entire display engine fused off as well.

> 
> after all the fuse handling. Would also fix any misconfiguration in
> i915_pci.c.
> 
> 
> BR,
> Jani.
> 
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center

-- 
Ville Syrjälä
Intel