Re: [PATCH 1/7] drm/i915/sdvo: Fix AVI infoframe TX rate readout

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

On Tue, Apr 09, 2019 at 10:16:04PM +0100, Chris Wilson wrote:
> Quoting Ville Syrjala (2019-04-09 15:40:48)
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > The AVI infoframe readout code currently issues a
> > SDVO_CMD_GET_HBUF_TXRATE before SDVO_CMD_SET_HBUF_INDEX, which is
> > not the correct order for these two operations. So far this wasn't
> > a problem since we left the index pointing at the AVI infoframe
> > buffer at the end of the modeset. However once we start to write
> > to other buffers (namely ELD) that is no longer going to be true.
> > Fix up the order so that we always read out the TX rate for the
> > correct buffer.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_sdvo.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
> > index 0e3d91d9ef13..61db07244296 100644
> > --- a/drivers/gpu/drm/i915/intel_sdvo.c
> > +++ b/drivers/gpu/drm/i915/intel_sdvo.c
> > @@ -1001,6 +1001,11 @@ static ssize_t intel_sdvo_read_infoframe(struct intel_sdvo *intel_sdvo,
> >         if (av_split < if_index)
> >                 return 0;
> >  
> > +       if (!intel_sdvo_set_value(intel_sdvo,
> > +                                 SDVO_CMD_SET_HBUF_INDEX,
> > +                                 set_buf_index, 2))
> > +               return -ENXIO;
> 
> That is consistent with write_infoframe and makes a modicum of sense.
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> 
> Why is the av_split separate from the if_index? What does that mean, at
> some point I might have to read the docs!

av_split specifies how the set of available buffers is split
between video and audio. if_index specifies which buffers the
other commands operate on.

-- 
Ville Syrjälä
Intel
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