Re: [PATCH v3] drm/i915/audio: treat UHBR SST like MST for cpu_transcoder signalling

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 08 Jul 2026, Mitul Golani <mitulkumar.ajitkumar.golani@intel.com> wrote:
> Both DP MST and UHBR SST require the audio component to use a real
> cpu_transcoder (>= 0) value to identify the audio stream on a port.
> For DP MST this was already handled; for UHBR SST it was not, causing
> pin_eld_notify() to signal cpu_transcoder = -1 (the legacy SST sentinel)
> and find_audio_state() to skip the per-transcoder entry for the UHBR
> stream.
>
> After suspend/resume or replug, the ELD lookup fails and audio goes
> silent. Fix by detecting UHBR SST alongside DP MST when deciding
> whether a real cpu_transcoder value must be used for audio state
> addressing, in both the pin_eld_notify() signalling and the
> find_audio_state() lookup paths.

[snip]

Going through some merged patches while writing the pull request...

>  
> -	/* Non-MST */
> +	/* Legacy SST. */

Please be careful about tossing around "legacy". It's the bog standard
DP 1.4 non-UHBR SST that's used absolutely everywere that you're talking
about here. It's not "legacy".

BR,
Jani.


-- 
Jani Nikula, Intel