[Intel-gfx] [PATCH 2/5] drm/i915/psr: Refactor psr short pulse handler

[Matt Roper]

On Tue, Nov 05, 2019 at 05:45:01PM -0800, José Roberto de Souza wrote:
> eDP spec states that when sink enconters a problem that prevents it
> to keep PSR running it should set PSR status to internal error and
> set the reason why it happen to PSR_ERROR_STATUS but it is not how it
> was implemented.
> But also I don't want to change this behavior, who knows if there is
> a panel out there that only set the PSR_ERROR_STATUS.
> 
> So here refactoring the code a bit to make more easy to read what was
> state above as more checks will be added to this function.
> 
> Cc: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_psr.c | 51 ++++++++++++++----------
>  1 file changed, 31 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index 0d84ea28bc6f..f38da1b9b323 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -1386,11 +1386,30 @@ void intel_psr_init(struct drm_i915_private *dev_priv)
>  	mutex_init(&dev_priv->psr.lock);
>  }
>  
> +static bool psr_get_status_and_error_status(struct intel_dp *intel_dp,
> +					    u8 *status, u8 *error_status)

This should probably return an integer rather than a bool to match the
kernel coding style guidelines:

        """
        If the name of a function is an action or an imperative command,
        the function should return an error-code integer.  If the name
        is a predicate, the function should return a "succeeded"
        boolean.
        """


Matt

> +{
> +	struct drm_dp_aux *aux = &intel_dp->aux;
> +	int r;
> +
> +	r = drm_dp_dpcd_readb(aux, DP_PSR_STATUS, status);
> +	if (r != 1)
> +		return false;
> +
> +	r = drm_dp_dpcd_readb(aux, DP_PSR_ERROR_STATUS, error_status);
> +	if (r != 1)
> +		return false;
> +
> +	*status = *status & DP_PSR_SINK_STATE_MASK;
> +
> +	return true;
> +}
> +
>  void intel_psr_short_pulse(struct intel_dp *intel_dp)
>  {
>  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
>  	struct i915_psr *psr = &dev_priv->psr;
> -	u8 val;
> +	u8 status, error_status;
>  	const u8 errors = DP_PSR_RFB_STORAGE_ERROR |
>  			  DP_PSR_VSC_SDP_UNCORRECTABLE_ERROR |
>  			  DP_PSR_LINK_CRC_ERROR;
> @@ -1403,38 +1422,30 @@ void intel_psr_short_pulse(struct intel_dp *intel_dp)
>  	if (!psr->enabled || psr->dp != intel_dp)
>  		goto exit;
>  
> -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_PSR_STATUS, &val) != 1) {
> -		DRM_ERROR("PSR_STATUS dpcd read failed\n");
> +	if (!psr_get_status_and_error_status(intel_dp, &status, &error_status)) {
> +		DRM_ERROR("Error reading PSR status or error status\n");
>  		goto exit;
>  	}
>  
> -	if ((val & DP_PSR_SINK_STATE_MASK) == DP_PSR_SINK_INTERNAL_ERROR) {
> -		DRM_DEBUG_KMS("PSR sink internal error, disabling PSR\n");
> +	if (status == DP_PSR_SINK_INTERNAL_ERROR || (error_status & errors)) {
>  		intel_psr_disable_locked(intel_dp);
>  		psr->sink_not_reliable = true;
>  	}
>  
> -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_PSR_ERROR_STATUS, &val) != 1) {
> -		DRM_ERROR("PSR_ERROR_STATUS dpcd read failed\n");
> -		goto exit;
> -	}
> -
> -	if (val & DP_PSR_RFB_STORAGE_ERROR)
> +	if (status == DP_PSR_SINK_INTERNAL_ERROR && !error_status)
> +		DRM_DEBUG_KMS("PSR sink internal error, disabling PSR\n");
> +	if (error_status & DP_PSR_RFB_STORAGE_ERROR)
>  		DRM_DEBUG_KMS("PSR RFB storage error, disabling PSR\n");
> -	if (val & DP_PSR_VSC_SDP_UNCORRECTABLE_ERROR)
> +	if (error_status & DP_PSR_VSC_SDP_UNCORRECTABLE_ERROR)
>  		DRM_DEBUG_KMS("PSR VSC SDP uncorrectable error, disabling PSR\n");
> -	if (val & DP_PSR_LINK_CRC_ERROR)
> +	if (error_status & DP_PSR_LINK_CRC_ERROR)
>  		DRM_DEBUG_KMS("PSR Link CRC error, disabling PSR\n");
>  
> -	if (val & ~errors)
> +	if (error_status & ~errors)
>  		DRM_ERROR("PSR_ERROR_STATUS unhandled errors %x\n",
> -			  val & ~errors);
> -	if (val & errors) {
> -		intel_psr_disable_locked(intel_dp);
> -		psr->sink_not_reliable = true;
> -	}
> +			  error_status & ~errors);
>  	/* clear status register */
> -	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_ERROR_STATUS, val);
> +	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_ERROR_STATUS, error_status);
>  exit:
>  	mutex_unlock(&psr->lock);
>  }
> -- 
> 2.24.0
> 
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-- 
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation
(916) 356-2795