Re: [PATCH 3/4] drm/msm/dp: skip LTTPR init when no LTTPRs are present

[Saurabh Anand]

On 24-08-2026 18:45, Konrad Dybcio wrote:
> On 8/24/26 1:28 PM, Saurabh Anand wrote:
> > drm_dp_lttpr_count() returns 0 when no LTTPRs are detected and a
> > negative value on error. The previous code passed the result directly
> > to drm_dp_lttpr_init() without checking, which would call into the
> > LTTPR transparency-mode setup with a zero or negative repeater count.
> >
> > Add an early return for lttpr_count <= 0 to skip the init entirely
> > when there are no repeaters in the link, matching the expected usage
> > of drm_dp_lttpr_init().
> Reading the body of that function, I'm not sure your statement is true

drm_dp_lttpr_count() returns 0 when no LTTPRs are detected and a
negative error code when the LTTPR common capabilities report an invalid
or unsupported repeater count.

drm_dp_lttpr_init() already handles the zero-count case by returning
early. However, when passed a negative count, it still writes transparent
mode before returning -ENODEV.

I will update the commit message giving more details.

> Konrad