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 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;

after all the fuse handling. Would also fix any misconfiguration in
i915_pci.c.


BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center