On Mon, Nov 19, 2018 at 05:51:31PM +0200, Ville Syrjälä wrote:
> On Mon, Nov 19, 2018 at 04:41:09PM +0200, Imre Deak wrote:
> > Add a comment to the pipe and transcoder enum definitions about our
> > assumption in the code that pipe==transcoder for PIPE_A-C /
> > TRANSCODER_A-C. This means we have to keep the values for these
> > pipe/transcoder enums fixed.
> >
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> > Cc: Mika Kahola <mika.kahola@xxxxxxxxx>
> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/intel_display.h | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.h b/drivers/gpu/drm/i915/intel_display.h
> > index 43eb4ebbcc35..cbb5d79d6a4c 100644
> > --- a/drivers/gpu/drm/i915/intel_display.h
> > +++ b/drivers/gpu/drm/i915/intel_display.h
> > @@ -43,6 +43,10 @@ enum i915_gpio {
> > GPIOM,
> > };
> >
> > +/*
> > + * Keep the PIPE_A-C values fixed, we assume that pipe==transcoder for
> > + * these pipes.
> > + */
>
> I suspect the A-C part is going to bitrot. Also I'm sure we
> make more assupmtions about these values (PIPE_A == 0,
> PIPE_N+1 == n+1, etc.). We should probably try to spell it
> all out here.
Ok, can add instead:
/*
* Keep the pipe enum values fixed: the code assumes that PIPE_A=0, the
* rest have consecutive values and match the enum values of transcoders
* with a 1:1 transcoder->pipe mapping.
*/
>
> > enum pipe {
> > INVALID_PIPE = -1,
> >
> > @@ -56,6 +60,10 @@ enum pipe {
> >
> > #define pipe_name(p) ((p) + 'A')
> >
> > +/*
> > + * Keep the TRANSCODER_A-C values fixed, we assume that pipe==transcoder for
> > + * these transcoders.
> > + */
>
> Same issue with the A-C part perhaps.
and here:
>
> > enum transcoder {
/*
* The following transcoders have a 1:1 transcoder->pipe mapping, keep
* their values fixed: the code assumes that TRANSCODER_A=0, the rest
* have consecutive values and match the enum values of the pipes they map
* to.
*/
> > TRANSCODER_A = 0,
> > TRANSCODER_B,
> > TRANSCODER_C,
/*
* The following transcoders can map to any pipe, their enum value
* doesn't need to stay fixed.
*/
> > TRANSCODER_EDP,
> > TRANSCODER_DSI_0,
> > TRANSCODER_DSI_1,
> > --
> > 2.13.2
>
> --
> Ville Syrjälä
> Intel
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