[Intel-gfx] [PATCH 7/8] drm/i915/psr: Don't tell sink that main link will be active in PSR2

[Souza, Jose]

On Wed, 2018-09-26 at 17:46 +0000, Souza, Jose wrote:
> On Mon, 2018-09-24 at 23:02 -0700, dhinakaran.pandiyan at gmail.com
> wrote:
> > On Thu, 2018-09-20 at 13:43 -0700, José Roberto de Souza wrote:
> > > For PSR2 we don't have the option to keep main link enabled while
> > > PSR2 is active, so don't configure sink DPCD with a wrong value.
> > 
> > Is this what the DP spec says or an Intel HW restriction?
> 
> This is Intel HW restriction as there is no register in PSR2 CTL to
> keep link in standby, DP spec states that link can be kept on or off
> while PSR2 is active, there is just a new timming restriction to turn
> link off.

I will update the commit message to make it clear:

For PSR2 there is no register to tell HW to keep main link enabled
while PSR2 is active, so don't configure sink DPCD with a
wrong value.


> 
> > 
> > -DK
> > 
> > > 
> > > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>s
> > > Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_psr.c | 9 +++++----
> > >  1 file changed, 5 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_psr.c
> > > b/drivers/gpu/drm/i915/intel_psr.c
> > > index cf9d6e965697..60cf6fd251d0 100644
> > > --- a/drivers/gpu/drm/i915/intel_psr.c
> > > +++ b/drivers/gpu/drm/i915/intel_psr.c
> > > @@ -344,12 +344,13 @@ static void intel_psr_enable_sink(struct
> > > intel_dp *intel_dp)
> > >  		drm_dp_dpcd_writeb(&intel_dp->aux,
> > > DP_RECEIVER_ALPM_CONFIG,
> > >  				   DP_ALPM_ENABLE);
> > >  		dpcd_val |= DP_PSR_ENABLE_PSR2 |
> > > DP_PSR_IRQ_HPD_WITH_CRC_ERRORS;
> > > +	} else {
> > > +		if (dev_priv->psr.link_standby)
> > > +			dpcd_val |= DP_PSR_MAIN_LINK_ACTIVE;
> > > +		if (INTEL_GEN(dev_priv) >= 8)
> > > +			dpcd_val |= DP_PSR_CRC_VERIFICATION;
> > >  	}
> > >  
> > > -	if (dev_priv->psr.link_standby)
> > > -		dpcd_val |= DP_PSR_MAIN_LINK_ACTIVE;
> > > -	if (!dev_priv->psr.psr2_enabled && INTEL_GEN(dev_priv) >= 8)
> > > -		dpcd_val |= DP_PSR_CRC_VERIFICATION;
> > >  	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, dpcd_val);
> > >  
> > >  	drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER,
> > > DP_SET_POWER_D0);
> 
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