Re: [PATCH v2 1/2] drm/i915/psr: Check drm_dp_dpcd_read return value on PSR dpcd init

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

On Thu, 21 Aug 2025, Jouni Högander <jouni.hogander@intel.com> wrote:
> Currently we are ignoriong drm_dp_dpcd_read return values when reading PSR
> and Panel Replay capability DPCD register. Rework intel_psr_dpcd a bit to
> take care of checking the return value.
>
> v2: use drm_dp_dpcd_read_data
>
> Signed-off-by: Jouni Högander <jouni.hogander@intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>


> ---
>  drivers/gpu/drm/i915/display/intel_psr.c | 32 ++++++++++++++++--------
>  1 file changed, 21 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index 609df53f1ef1..5addde63168e 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -580,6 +580,16 @@ static void intel_dp_get_su_granularity(struct intel_dp *intel_dp)
>  static void _panel_replay_init_dpcd(struct intel_dp *intel_dp)
>  {
>  	struct intel_display *display = to_intel_display(intel_dp);
> +	int ret;
> +
> +	ret = drm_dp_dpcd_read_data(&intel_dp->aux, DP_PANEL_REPLAY_CAP_SUPPORT,
> +				    &intel_dp->pr_dpcd, sizeof(intel_dp->pr_dpcd));
> +	if (ret < 0)
> +		return;
> +
> +	if (!(intel_dp->pr_dpcd[INTEL_PR_DPCD_INDEX(DP_PANEL_REPLAY_CAP_SUPPORT)] &
> +	      DP_PANEL_REPLAY_SUPPORT))
> +		return;
>  
>  	if (intel_dp_is_edp(intel_dp)) {
>  		if (!intel_alpm_aux_less_wake_supported(intel_dp)) {
> @@ -611,6 +621,15 @@ static void _panel_replay_init_dpcd(struct intel_dp *intel_dp)
>  static void _psr_init_dpcd(struct intel_dp *intel_dp)
>  {
>  	struct intel_display *display = to_intel_display(intel_dp);
> +	int ret;
> +
> +	ret = drm_dp_dpcd_read_data(&intel_dp->aux, DP_PSR_SUPPORT, intel_dp->psr_dpcd,
> +				    sizeof(intel_dp->psr_dpcd));
> +	if (ret < 0)
> +		return;
> +
> +	if (!intel_dp->psr_dpcd[0])
> +		return;
>  
>  	drm_dbg_kms(display->drm, "eDP panel supports PSR version %x\n",
>  		    intel_dp->psr_dpcd[0]);
> @@ -656,18 +675,9 @@ static void _psr_init_dpcd(struct intel_dp *intel_dp)
>  
>  void intel_psr_init_dpcd(struct intel_dp *intel_dp)
>  {
> -	drm_dp_dpcd_read(&intel_dp->aux, DP_PSR_SUPPORT, intel_dp->psr_dpcd,
> -			 sizeof(intel_dp->psr_dpcd));
> -
> -	drm_dp_dpcd_read(&intel_dp->aux, DP_PANEL_REPLAY_CAP_SUPPORT,
> -			 &intel_dp->pr_dpcd, sizeof(intel_dp->pr_dpcd));
> -
> -	if (intel_dp->pr_dpcd[INTEL_PR_DPCD_INDEX(DP_PANEL_REPLAY_CAP_SUPPORT)] &
> -	    DP_PANEL_REPLAY_SUPPORT)
> -		_panel_replay_init_dpcd(intel_dp);
> +	_psr_init_dpcd(intel_dp);
>  
> -	if (intel_dp->psr_dpcd[0])
> -		_psr_init_dpcd(intel_dp);
> +	_panel_replay_init_dpcd(intel_dp);
>  
>  	if (intel_dp->psr.sink_psr2_support ||
>  	    intel_dp->psr.sink_panel_replay_su_support)

-- 
Jani Nikula, Intel