[PATCH v5 6/8] drm/i915/lobf: Check for sink error and disable LOBF

[Hogander, Jouni]

On Mon, 2025-03-03 at 14:05 +0530, Animesh Manna wrote:
> Disable LOBF/ALPM for any erroneous condition from sink side.
> 
> v1: Initial version.
> v2: Add centralized alpm error handling. [Jouni]
> 
> Signed-off-by: Animesh Manna <animesh.manna at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_alpm.c | 25
> +++++++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_alpm.h |  1 +
>  drivers/gpu/drm/i915/display/intel_dp.c   |  3 +++
>  drivers/gpu/drm/i915/display/intel_psr.c  | 15 ++------------
>  4 files changed, 31 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c
> b/drivers/gpu/drm/i915/display/intel_alpm.c
> index 245364d031c1..c3d13d93c779 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -512,3 +512,28 @@ void intel_alpm_disable(struct intel_dp
> *intel_dp)
>  		     PORT_ALPM_CTL(cpu_transcoder),
>  		     PORT_ALPM_CTL_ALPM_AUX_LESS_ENABLE, 0);
>  }
> +
> +bool intel_alpm_get_error(struct intel_dp *intel_dp)
> +{
> +	struct intel_display *display = to_intel_display(intel_dp);
> +	struct drm_dp_aux *aux = &intel_dp->aux;
> +	u8 val;
> +	int r;
> +
> +	r = drm_dp_dpcd_readb(aux, DP_RECEIVER_ALPM_STATUS, &val);
> +	if (r != 1) {
> +		drm_err(display->drm, "Error reading ALPM
> status\n");
> +		return true;
> +	}
> +
> +	if (val & DP_ALPM_LOCK_TIMEOUT_ERROR) {
> +		drm_dbg_kms(display->drm,
> +			    "ALPM lock timeout error, disabling
> ALPM\n");

I think you should remove ", disabling ALPM" from here. You could add
it into intel_alpm_disable. Also having drm_dbg about enabling LOBF in
lnl_alpm_configure would make sense.

> +
> +		/* Clearing error */
> +		drm_dp_dpcd_writeb(aux, DP_RECEIVER_ALPM_STATUS,
> val);
> +		return true;
> +	}
> +
> +	return false;
> +}
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.h
> b/drivers/gpu/drm/i915/display/intel_alpm.h
> index c6efd25c2062..22469fd4cba5 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.h
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.h
> @@ -30,4 +30,5 @@ void intel_alpm_lobf_debugfs_add(struct
> intel_connector *connector);
>  bool intel_alpm_aux_wake_supported(struct intel_dp *intel_dp);
>  bool intel_alpm_aux_less_wake_supported(struct intel_dp *intel_dp);
>  void intel_alpm_disable(struct intel_dp *intel_dp);
> +bool intel_alpm_get_error(struct intel_dp *intel_dp);
>  #endif
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 4d0166f17357..3aa3c4ab97d1 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -5359,6 +5359,9 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
>  
>  	intel_psr_short_pulse(intel_dp);
>  
> +	if (intel_alpm_get_error(intel_dp))
> +		intel_alpm_disable(intel_dp);
> +
>  	if (intel_dp_test_short_pulse(intel_dp))
>  		reprobe_needed = true;
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> b/drivers/gpu/drm/i915/display/intel_psr.c
> index 1d202f2eb356..fde9463d5ec9 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -3406,28 +3406,17 @@ static int
> psr_get_status_and_error_status(struct intel_dp *intel_dp,
>  static void psr_alpm_check(struct intel_dp *intel_dp)
>  {
>  	struct intel_display *display = to_intel_display(intel_dp);
> -	struct drm_dp_aux *aux = &intel_dp->aux;
>  	struct intel_psr *psr = &intel_dp->psr;
> -	u8 val;
> -	int r;
>  
>  	if (!psr->sel_update_enabled)
>  		return;
>  
> -	r = drm_dp_dpcd_readb(aux, DP_RECEIVER_ALPM_STATUS, &val);
> -	if (r != 1) {
> -		drm_err(display->drm, "Error reading ALPM
> status\n");
> -		return;
> -	}
> -
> -	if (val & DP_ALPM_LOCK_TIMEOUT_ERROR) {
> +	if (intel_alpm_get_error(intel_dp)) {
>  		intel_psr_disable_locked(intel_dp);
>  		psr->sink_not_reliable = true;
> +		intel_alpm_disable(intel_dp);
>  		drm_dbg_kms(display->drm,
>  			    "ALPM lock timeout error, disabling
> PSR\n");

You can remove this printout or change it as "ALPM error, disabling
PSR". ALPM lock timeout is already dumped out by intel_alpm_get_error
and intel_psr_disable_locked dumps Disabling PSR.

BR,

Jouni Högander
 
> -
> -		/* Clearing error */
> -		drm_dp_dpcd_writeb(aux, DP_RECEIVER_ALPM_STATUS,
> val);
>  	}
>  }
>