[Intel-gfx] [PATCH 07/11] drm/i915/dp: Exit PSR before do a aux channel transaction

[Souza, Jose]

On Mon, 2018-04-02 at 12:00 -0700, Pandiyan, Dhinakaran wrote:
> 
> 
> On Mon, 2018-04-02 at 11:23 -0700, Rodrigo Vivi wrote:
> > On Fri, Mar 30, 2018 at 03:23:32PM -0700, José Roberto de Souza
> > wrote:
> > > When PSR/PSR2 is enabled hardware can do aux ch transactions by
> > > it
> > > self.
> > > Spec requires that PSR is inactive before do any aux ch
> > > transaction
> > > in HSW and BDW, for skl+ there is a aux ch mutex but the use is
> > > not
> > > recommended.
> > > So exiting PSR/PSR2 and waiting the transition to inactive to
> > > prevent
> > > any concurrent access between hardware and software in aux ch
> > > registers.
> 
> Wouldn't the debugfs interface that you added to read sink PSR status
> always show PSR as disabled? Or do you intend to set
> intel_dp->exit_psr_on_aux_ch_xfer = true? 

Yeah it will always be disabled, unless when the hack in 'drm/i915:
Keep IGT PSR and frontbuffer tests functional' is set, Rodrigo asked to
remove the debugfs file that was controlling the state of the hack and
enable/disable it around CRC read so I could do that for the whole
i915_edp_psr_status too.

> 
> 
> > > 
> > > VLV and CHV hardware don't do any aux as software is responsible
> > > to
> > > do all the buffer tracking and it sends the wake up aux ch
> > > message
> > > to sink.
> > > 
> > 
> > ahh cool... I get back what I said on some previous patch.
> > I like where it is going, but...
> > 
> > > BSpec: 7530, 799 and 7532
> > > 
> > > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> > > Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > > Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_dp.c  | 38
> > > ++++++++++++++++++++++++++++++++++++++
> > >  drivers/gpu/drm/i915/intel_drv.h |  2 ++
> > >  drivers/gpu/drm/i915/intel_psr.c |  8 ++++++++
> > >  3 files changed, 48 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > > b/drivers/gpu/drm/i915/intel_dp.c
> > > index 62f82c4298ac..fedee4e7ed24 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -1062,6 +1062,41 @@ static uint32_t
> > > skl_get_aux_send_ctl(struct intel_dp *intel_dp,
> > >  	       DP_AUX_CH_CTL_SYNC_PULSE_SKL(32);
> > >  }
> > >  
> > > +/**
> > > + * intel_dp_aux_ch_get - Get total control of aux ch registers
> > > + *
> > > + * By exiting or disabling any hardware feature that can also
> > > use the aux ch
> > > + * registers at the same time as driver, this function will give
> > > total control
> > > + * of aux ch registers to driver.
> > > + */
> > > +static void intel_dp_aux_ch_get(struct intel_dp *intel_dp)
> > > +{
> > > +	if (!intel_dp->exit_psr_on_aux_ch_xfer)
> > > +		return;
> > > +
> > > +	intel_psr_activate_block_get(intel_dp);
> > > +	intel_psr_exit(intel_dp, true);
> > 
> > decision on exit and activate should be inside the block_get and
> > block_put,
> > based on current state of the counters.
> > 
> > > +}
> > > +
> > > +/**
> > > + * intel_dp_aux_ch_put - Release aux ch registers control
> > > + *
> > > + * It is the intel_dp_aux_ch_get() counterpart.
> > > + */
> > > +static void intel_dp_aux_ch_put(struct intel_dp *intel_dp)
> > > +{
> > > +	if (!intel_dp->exit_psr_on_aux_ch_xfer)
> > > +		return;
> > > +
> > > +	intel_psr_activate_block_put(intel_dp);
> > > +	/* Usually more than just one aux ch transaction is
> > > executed when
> > > +	 * handling some event, activating PSR right way would
> > > cause several
> > > +	 * msecs of delay waiting PSR to exit for each aux ch
> > > transaction, so
> > > +	 * here asking it to be scheduled.
> > > +	 */
> > > +	intel_psr_activate(intel_dp, true);
> > > +}
> > > +
> > >  static int
> > >  intel_dp_aux_xfer(struct intel_dp *intel_dp,
> > >  		  const uint8_t *send, int send_bytes,
> > > @@ -1101,6 +1136,8 @@ intel_dp_aux_xfer(struct intel_dp
> > > *intel_dp,
> > >  
> > >  	intel_dp_check_edp(intel_dp);
> > >  
> > > +	intel_dp_aux_ch_get(intel_dp);
> > > +
> > >  	/* Try to wait for any previous AUX channel activity */
> > >  	for (try = 0; try < 3; try++) {
> > >  		status = I915_READ_NOTRACE(ch_ctl);
> > > @@ -1223,6 +1260,7 @@ intel_dp_aux_xfer(struct intel_dp
> > > *intel_dp,
> > >  
> > >  	ret = recv_bytes;
> > >  out:
> > > +	intel_dp_aux_ch_put(intel_dp);
> > >  	pm_qos_update_request(&dev_priv->pm_qos,
> > > PM_QOS_DEFAULT_VALUE);
> > >  
> > >  	if (vdd)
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h
> > > b/drivers/gpu/drm/i915/intel_drv.h
> > > index 020b96324135..177478f0b032 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -1139,6 +1139,8 @@ struct intel_dp {
> > >  
> > >  	/* Displayport compliance testing */
> > >  	struct intel_dp_compliance compliance;
> > > +
> > > +	bool exit_psr_on_aux_ch_xfer;
> > >  };
> > >  
> > >  struct intel_lspcon {
> > > diff --git a/drivers/gpu/drm/i915/intel_psr.c
> > > b/drivers/gpu/drm/i915/intel_psr.c
> > > index 8702dbafb42d..f88f12246a23 100644
> > > --- a/drivers/gpu/drm/i915/intel_psr.c
> > > +++ b/drivers/gpu/drm/i915/intel_psr.c
> > > @@ -665,6 +665,13 @@ void intel_psr_enable(struct intel_dp
> > > *intel_dp,
> > >  				      msecs_to_jiffies(intel_dp-
> > > >panel_power_cycle_delay * 5));
> > >  	}
> > >  
> > > +	/* From all platforms that supports PSR/PSR2 this 2 is
> > > the ones that
> > > +	 * don't have restrictions about use of the aux ch while
> > > PSR/PSR2 is
> > > +	 * enabled.
> > > +	 */
> > > +	if (!(IS_VALLEYVIEW(dev_priv) ||
> > > IS_CHERRYVIEW(dev_priv)))
> > > +		intel_dp->exit_psr_on_aux_ch_xfer = true;
> > > +
> > >  unlock:
> > >  	mutex_unlock(&dev_priv->psr.lock);
> > >  }
> > > @@ -732,6 +739,7 @@ void intel_psr_disable(struct intel_dp
> > > *intel_dp,
> > >  
> > >  	dev_priv->psr.disable_source(intel_dp);
> > >  
> > > +	intel_dp->exit_psr_on_aux_ch_xfer = false;
> > >  	/* Disable PSR on Sink */
> > >  	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, 0);
> > >  
> > > -- 
> > > 2.16.3
> > >