Re: [PATCH] drm/i915: Fix psr sink status report.

[Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>]

On Thu, 2018-07-19 at 17:31 -0700, Rodrigo Vivi wrote:
> First of all don't try to read dpcd if PSR is not even supported.
> 
> But also, if read failed return -EIO instead of reporting via a
> backchannel.
> 
> v2: fix dev_priv: At this level m->private is the connector. (CI/DK)
>     don't convert dpcd read errors to EIO. (DK)
> 
> Fixes: 5b7b30864d1d ("drm/i915/psr: Split sink status into a separate
> debugfs node")
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> Cc: José Roberto de Souza <jose.souza@intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c
> b/drivers/gpu/drm/i915/i915_debugfs.c
> index b3aefd623557..59dc0610ea44 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2606,13 +2606,22 @@ static int i915_psr_sink_status_show(struct
> seq_file *m, void *data)
>  		"sink internal error",
>  	};
>  	struct drm_connector *connector = m->private;
> +	struct drm_i915_private *dev_priv = to_i915(connector->dev);
>  	struct intel_dp *intel_dp =
>  		enc_to_intel_dp(&intel_attached_encoder(connector)-
> >base);
> +	int ret;
> +
> +	if (!CAN_PSR(dev_priv)) {
> +		seq_puts(m, "PSR Unsupported\n");
> +		return -ENODEV;
> +	}
>  
>  	if (connector->status != connector_status_connected)
>  		return -ENODEV;
>  
> -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_PSR_STATUS, &val)
> == 1) {
> +	ret = drm_dp_dpcd_readb(&intel_dp->aux, DP_PSR_STATUS,
> &val);
> +
> +	if (ret == 1) {
>  		const char *str = "unknown";
>  
>  		val &= DP_PSR_SINK_STATE_MASK;
> @@ -2620,7 +2629,7 @@ static int i915_psr_sink_status_show(struct
> seq_file *m, void *data)
>  			str = sink_status[val];
>  		seq_printf(m, "Sink PSR status: 0x%x [%s]\n", val,
> str);
>  	} else {

dpcd_readb() is not expected to return anything other than 1 or a
negative error code, so this looks good.
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>


Are you also sending a similar fix for i915_dpcd_show()? That function
also prints a DRM_ERROR() for failed aux transactions.

> -		DRM_ERROR("dpcd read (at %u) failed\n",
> DP_PSR_STATUS);
> +		return ret;
>  	}
>  
>  	return 0;
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