Re: [PATCH 2/6] drm/i915/psr: Tie PSR2 support to Y coordinate requirement in intel_psr_init_dpcd()

["Souza, Jose" <jose.souza@intel.com>]

On Thu, 2018-03-15 at 17:35 -0700, Rodrigo Vivi wrote:
> On Wed, Mar 14, 2018 at 03:36:13PM -0700, José Roberto de Souza
> wrote:
> > Move to only one place the sink requirements that the actual driver
> > needs to enable PSR2.
> > 
> > Also intel_psr2_config_valid() is called every time the crtc config
> > is computed, wasting some time every time it was checking for
> > Y coordinate requirement.
> > 
> > This allow us to nuke y_cord_support and some of VSC setup code
> > that
> > was handling a scenario that would never happen(PSR2 without Y
> > coordinate).
> > 
> > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.h  |  1 -
> >  drivers/gpu/drm/i915/intel_psr.c | 55 ++++++++++++++++++++------
> > --------------
> >  2 files changed, 28 insertions(+), 28 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> > b/drivers/gpu/drm/i915/i915_drv.h
> > index 8a584273f897..d4bc8d18f56c 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -603,7 +603,6 @@ struct i915_psr {
> >  	unsigned busy_frontbuffer_bits;
> >  	bool psr2_support;
> >  	bool link_standby;
> > -	bool y_cord_support;
> >  	bool colorimetry_support;
> >  	bool alpm;
> >  	bool has_hw_tracking;
> > diff --git a/drivers/gpu/drm/i915/intel_psr.c
> > b/drivers/gpu/drm/i915/intel_psr.c
> > index 9811f5f0bc75..62d97d5576d1 100644
> > --- a/drivers/gpu/drm/i915/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/intel_psr.c
> > @@ -93,7 +93,7 @@ static void psr_aux_io_power_put(struct intel_dp
> > *intel_dp)
> >  	intel_display_power_put(dev_priv,
> > psr_aux_domain(intel_dp));
> >  }
> >  
> > -static bool intel_dp_get_y_cord_status(struct intel_dp *intel_dp)
> > +static bool intel_dp_get_y_coord_required(struct intel_dp
> > *intel_dp)
> >  {
> >  	uint8_t psr_caps = 0;
> >  
> > @@ -137,22 +137,38 @@ void intel_psr_init_dpcd(struct intel_dp
> > *intel_dp)
> >  
> >  	if (INTEL_GEN(dev_priv) >= 9 &&
> >  	    (intel_dp->psr_dpcd[0] & DP_PSR2_IS_SUPPORTED)) {
> > -		uint8_t frame_sync_cap;
> > +		uint8_t frame_sync_cap, y_coord_req;
> >  
> >  		dev_priv->psr.sink_support = true;
> > +
> > +		/* PSR2 needs frame sync to do selective updates
> > */
> >  		if (drm_dp_dpcd_readb(&intel_dp->aux,
> >  				      DP_SINK_DEVICE_AUX_FRAME_SYN
> > C_CAP,
> >  				      &frame_sync_cap) != 1)
> >  			frame_sync_cap = 0;
> >  		frame_sync_cap = (frame_sync_cap &
> > DP_AUX_FRAME_SYNC_CAP);
> > -		/* PSR2 needs frame sync as well */
> > -		dev_priv->psr.psr2_support = frame_sync_cap;
> > -		DRM_DEBUG_KMS("PSR2 %s on sink",
> > -			      dev_priv->psr.psr2_support ?
> > "supported" : "not supported");
> > +
> > +		/*
> > +		 * FIXME: Enable PSR2 only for y-coordinate PSR2
> > panels
> > +		 * After GTC implementation, remove this
> > restriction.
> 
> I believe we should remove the FIXME and just comment out that non y-
> coordinate
> would need GTC that we currently don't implement.
> 
> later if we change our minds and decided to add that support we
> revisit here
> but without a FIXME poluting code for something we don't plan to
> support for now.
> 
> > +		 *
> > +		 * All panels that supports PSR version 3 that is
> 
> PSRv3? is there really something formal about that?

Yes, from eDP spec:

PSR Support and Version

00h = Panel Self Refresh Capability is not supported (default).
If PSR/PSR2 is supported, the SET_POWER_CAPABLE bit in the
EDP_GENERAL_CAPABILITY_1 register (DPCD Address 00701h, bit 7) must
be set to 1.
01h = Panel Self Refresh capability is supported, PSR version is 01h
(PSR).
02h = Panel Self Refresh with Selective Update (SU) capability is
supported,
PSR version is 02h (PSR2). Y-coordinates for SU are not supported.
Supported
by eDP v1.4 (and higher).
03h = Panel Self Refresh with SU capability and Y-coordinate supported,
PSR
version is 03h (PSR2 + Y-coordinate). Supported by eDP v1.4a (and
higher).

> 
> > +		 * PSR2 + Y-coordinate support can handle Y
> > coordinates in VSC
> > +		 * but we are only sure that it is going to be
> > used when
> > +		 * required by the panel. This way panel is
> > capable to do
> > +		 * selective update even without a valid aux frame
> > sync.
> > +		 */
> > +		y_coord_req =
> > intel_dp_get_y_coord_required(intel_dp);
> > +
> > +		dev_priv->psr.psr2_support = frame_sync_cap &&
> > y_coord_req;
> > +		if (dev_priv->psr.psr2_support)
> > +			DRM_DEBUG_KMS("PSR2 supported on sink\n");
> > +		else
> > +			DRM_DEBUG_KMS("PSR2 not supported on sink"
> > +				      "(frame sync: %d Y-coord
> > required: %d)\n",
> > +				      frame_sync_cap,
> > y_coord_req);
> >  
> >  		if (dev_priv->psr.psr2_support) {
> > -			dev_priv->psr.y_cord_support =
> > -				intel_dp_get_y_cord_status(intel_d
> > p);
> >  			dev_priv->psr.colorimetry_support =
> >  				intel_dp_get_colorimetry_status(in
> > tel_dp);
> >  			dev_priv->psr.alpm =
> > @@ -198,16 +214,12 @@ static void hsw_psr_setup_vsc(struct intel_dp
> > *intel_dp,
> >  		memset(&psr_vsc, 0, sizeof(psr_vsc));
> >  		psr_vsc.sdp_header.HB0 = 0;
> >  		psr_vsc.sdp_header.HB1 = 0x7;
> > -		if (dev_priv->psr.colorimetry_support &&
> > -		    dev_priv->psr.y_cord_support) {
> > +		if (dev_priv->psr.colorimetry_support) {
> >  			psr_vsc.sdp_header.HB2 = 0x5;
> >  			psr_vsc.sdp_header.HB3 = 0x13;
> > -		} else if (dev_priv->psr.y_cord_support) {
> > +		} else {
> >  			psr_vsc.sdp_header.HB2 = 0x4;
> >  			psr_vsc.sdp_header.HB3 = 0xe;
> > -		} else {
> > -			psr_vsc.sdp_header.HB2 = 0x3;
> > -			psr_vsc.sdp_header.HB3 = 0xc;
> >  		}
> >  	} else {
> >  		/* Prepare VSC packet as per EDP 1.3 spec, Table
> > 3.10 */
> > @@ -478,15 +490,6 @@ static bool intel_psr2_config_valid(struct
> > intel_dp *intel_dp,
> >  		return false;
> >  	}
> >  
> > -	/*
> > -	 * FIXME:enable psr2 only for y-cordinate psr2 panels
> > -	 * After gtc implementation , remove this restriction.
> > -	 */
> > -	if (!dev_priv->psr.y_cord_support) {
> > -		DRM_DEBUG_KMS("PSR2 not enabled, panel does not
> > support Y coordinate\n");
> > -		return false;
> > -	}
> > -
> >  	return true;
> >  }
> >  
> > @@ -586,14 +589,12 @@ static void hsw_psr_enable_source(struct
> > intel_dp *intel_dp,
> >  	struct drm_device *dev = dig_port->base.base.dev;
> >  	struct drm_i915_private *dev_priv = to_i915(dev);
> >  	enum transcoder cpu_transcoder = crtc_state-
> > >cpu_transcoder;
> > -	u32 chicken;
> >  
> >  	psr_aux_io_power_get(intel_dp);
> >  
> >  	if (dev_priv->psr.psr2_support) {
> > -		chicken = PSR2_VSC_ENABLE_PROG_HEADER;
> > -		if (dev_priv->psr.y_cord_support)
> > -			chicken |= PSR2_ADD_VERTICAL_LINE_COUNT;
> > +		u32 chicken = PSR2_VSC_ENABLE_PROG_HEADER
> > +			      | PSR2_ADD_VERTICAL_LINE_COUNT;
> >  		I915_WRITE(CHICKEN_TRANS(cpu_transcoder),
> > chicken);
> >  
> >  		I915_WRITE(EDP_PSR_DEBUG,
> > -- 
> > 2.16.2
> > 
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