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

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Thu, Jul 19, 2018 at 06:52:00PM -0700, Dhinakaran Pandiyan wrote:
> 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>

thanks, pushed.

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

well... it is a bit different there because we cannot return in the middle
of the loop because we might want to get other regs read. but probably it
is a good idea to print the error message along with the reads so you don't
have to look to 2 places.

I will put a simple patch and we can wait until Jani is back from
vacation since he was the author there.

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