[Intel-gfx] [PATCH] drm/i915/display: Return correct err code for bpc < 0

[Ville Syrjälä]

On Tue, Apr 11, 2023 at 05:07:01PM -0700, Manasi Navare wrote:
> On Tue, Apr 11, 2023 at 10:42 AM Ville Syrjälä
> <ville.syrjala at linux.intel.com> wrote:
> >
> > On Tue, Apr 11, 2023 at 05:34:08PM +0000, Manasi Navare wrote:
> > > In the function intel_dp_max_bpp(), currently if bpc < 0 in case of error,
> > > we return 0 instead of returning an err code of -EINVAL.
> > > This throws off the logic in the calling function.
> >
> > What logic? The caller doesn't expect to get an error.
> 
> If this returns a 0, we end up using limits.max_bpp = 0 and in
> intel_dp_compute_link_config_wide(),
> since max_bpp is 0, it exits this for loop:
> 
> for (bpp = limits->max_bpp; bpp >= limits->min_bpp; bpp -= 2 * 3) and returns
> -EINVAL which then wrongly goes to enable DSC even when link BW is
> sufficient without DSC.

And how woud max_bpp<0 prevent that?

The real problem seems to be that the DSC code totally
ignores bpp limits.

-- 
Ville Syrjälä
Intel