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

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 22 Sep 2022, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Thu, Sep 22, 2022 at 12:36:46PM +0300, Ville Syrjälä wrote:
>> 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.
>
> Well, I guess I already did that partially in eg. skl_fbc_id_for_pipe()
> though that one does allow for a difference in bias at least.

Regardless, scratch what I just said, I don't like it either. For
whatever reason I momentarily thought fbc_mask was indexed using
pipes. *facepalm*.

Sorry for the noise.

BR,
Jani.


>
>> 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

-- 
Jani Nikula, Intel Open Source Graphics Center