Re: [PATCH] drm/i915: Use dpcd read wake for sink crc calls.

["Thulasimani, Sivakumar" <sivakumar.thulasimani@xxxxxxxxx>]

On 8/25/2015 2:50 AM, Vivi, Rodrigo wrote:
> On Mon, 2015-08-24 at 19:54 +0000, Zanoni, Paulo R wrote:
> > Em Qui, 2015-08-20 às 16:23 -0700, Rodrigo Vivi escreveu:
> > > Let's use a native read with retry as suggested per spec to
> > > fix Sink CRC on SKL when PSR is enabled.
> > >
> > > With PSR enabled panel is probably taking more time to wake
> > > and dpcd read is faling.
> > Does this commit actually fix any known problem with Sink CRC? Or is
> > it
> > just a try? It would be nice to have this clarified in the commit
> > message.
> It was just a try but that made sink crc working on my SKL when PSR is
> enabled. nothing much to add...
SKL has new register AUX_MUTEX which should be used when accessing dpcd
on edp. just searched the nightly code and could not find it. it might 
be the reason
for random dpcd failures reported in the other thread.

regards,
Sivakumar
> > Anyway, it looks correct, so:
> > Reviewed-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
> >
> > > v2: Fix my email domain on commit message. Thanks Rafael.
> > >
> > > Cc: Rafael Antognolli <rafael.antognolli@xxxxxxxxx>
> > > Cc: Sonika Jindal <sonika.jindal@xxxxxxxxx>
> > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> > > ---
> > >   drivers/gpu/drm/i915/intel_dp.c | 15 +++++++++------
> > >   1 file changed, 9 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > > b/drivers/gpu/drm/i915/intel_dp.c
> > > index d32ce48..34f5e33 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -4037,7 +4037,8 @@ static int intel_dp_sink_crc_stop(struct
> > > intel_dp *intel_dp)
> > >   	u8 buf;
> > >   	int ret = 0;
> > >   
> > > -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf)
> > > <
> > > 0) {
> > > +	if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_TEST_SINK,
> > > +				    &buf, 1) < 0) {
> > >   		DRM_DEBUG_KMS("Sink CRC couldn't be stopped
> > > properly\n");
> > >   		ret = -EIO;
> > >   		goto out;
> > > @@ -4069,7 +4070,8 @@ static int intel_dp_sink_crc_start(struct
> > > intel_dp *intel_dp)
> > >   			return ret;
> > >   	}
> > >   
> > > -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK_MISC,
> > > &buf) < 0)
> > > +	if (intel_dp_dpcd_read_wake(&intel_dp->aux,
> > > DP_TEST_SINK_MISC,
> > > +				    &buf, 1) < 0)
> > >   		return -EIO;
> > >   
> > >   	if (!(buf & DP_TEST_CRC_SUPPORTED))
> > > @@ -4077,7 +4079,7 @@ static int intel_dp_sink_crc_start(struct
> > > intel_dp *intel_dp)
> > >   
> > >   	intel_dp->sink_crc.last_count = buf & DP_TEST_COUNT_MASK;
> > >   
> > > -	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_SINK, &buf)
> > > <
> > > 0)
> > > +	if (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_TEST_SINK,
> > > &buf, 1) < 0)
> > >   		return -EIO;
> > >   
> > >   	hsw_disable_ips(intel_crtc);
> > > @@ -4109,8 +4111,8 @@ int intel_dp_sink_crc(struct intel_dp
> > > *intel_dp, u8 *crc)
> > >   	do {
> > >   		intel_wait_for_vblank(dev, intel_crtc->pipe);
> > >   
> > > -		if (drm_dp_dpcd_readb(&intel_dp->aux,
> > > -				      DP_TEST_SINK_MISC, &buf) <
> > > 0)
> > > {
> > > +		if (intel_dp_dpcd_read_wake(&intel_dp->aux,
> > > +					    DP_TEST_SINK_MISC,
> > > &buf,
> > > 1) < 0) {
> > >   			ret = -EIO;
> > >   			goto stop;
> > >   		}
> > > @@ -4123,7 +4125,8 @@ int intel_dp_sink_crc(struct intel_dp
> > > *intel_dp, u8 *crc)
> > >   		if (count == 0)
> > >   			intel_dp->sink_crc.last_count = 0;
> > >   
> > > -		if (drm_dp_dpcd_read(&intel_dp->aux,
> > > DP_TEST_CRC_R_CR, crc, 6) < 0) {
> > > +		if (intel_dp_dpcd_read_wake(&intel_dp->aux,
> > > DP_TEST_CRC_R_CR,
> > > +					    crc, 6) < 0) {
> > >   			ret = -EIO;
> > >   			goto stop;
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