Re: [PATCH v3 2/6] drm/i915/display/icl: Enable TRANSCODER PORT SYNC for tiled displays across separate ports

[Manasi Navare <manasi.d.navare@intel.com>]

On Mon, Sep 30, 2019 at 05:19:09PM +0300, Ville Syrjälä wrote:
> On Sun, Sep 22, 2019 at 10:08:03AM -0700, Manasi Navare wrote:
> > In case of tiled displays where different tiles are displayed across
> > different ports, we need to synchronize the transcoders involved.
> > This patch implements the transcoder port sync feature for
> > synchronizing one master transcoder with one or more slave
> > transcoders. This is only enbaled in slave transcoder
> > and the master transcoder is unaware that it is operating
> > in this mode.
> > This has been tested with tiled display connected to ICL.
> > 
> > v5:
> > * Add TRANSCODER_D case and MISSING_CASE (Maarten)
> > v4:
> > Rebase
> > v3:
> > * Check of DP_MST moved to atomic_check (Maarten)
> > v2:
> > * Do not use RMW, just write to the register in commit (Jani N)
> > 
> > Cc: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Matt Roper <matthew.d.roper@intel.com>
> > Cc: Jani Nikula <jani.nikula@intel.com>
> > Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
> > Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 46 ++++++++++++++++++++
> >  1 file changed, 46 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index 4ff375d5852d..1ae5eafe2892 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -4426,6 +4426,49 @@ static void icl_set_pipe_chicken(struct intel_crtc *crtc)
> >  	I915_WRITE(PIPE_CHICKEN(pipe), tmp);
> >  }
> >  
> > +static void icl_enable_trans_port_sync(const struct intel_crtc_state *crtc_state)
> > +{
> > +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
> > +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> > +	u32 trans_ddi_func_ctl2_val;
> > +	u8 master_select;
> > +
> > +	/*
> > +	 * Configure the master select and enable Transcoder Port Sync for
> > +	 * Slave CRTCs transcoder.
> > +	 */
> > +	if (crtc_state->master_transcoder == INVALID_TRANSCODER)
> > +		return;
> > +
> > +	switch (crtc_state->master_transcoder) {
> > +	case TRANSCODER_A:
> > +		master_select = 1;
> > +		break;
> > +	case TRANSCODER_B:
> > +		master_select = 2;
> > +		break;
> > +	case TRANSCODER_C:
> > +		master_select = 3;
> > +		break;
> > +	case TRANSCODER_D:
> > +		master_select = 4;
> > +		break;
> 
> That's all just master_transcoder+1.
>

So just get rid of the switch statement and add master_transcoder +1?
 
> > +	case TRANSCODER_EDP:
> 
> EDP transcoder can be master. The MISSING_CASE is wrong for EDP.

Yes, EDP trans cannot be a slave but can be a master, so I guess for that case just
have if (TRANSCODER_EDP), master_Select == 0?

Manasi

> 
> > +	default:
> > +		MISSING_CASE(crtc_state->master_transcoder);
> > +		master_select = 0;
> > +	}
> > +	/* Set the master select bits for Tranascoder Port Sync */
> > +	trans_ddi_func_ctl2_val = (PORT_SYNC_MODE_MASTER_SELECT(master_select) &
> > +				   PORT_SYNC_MODE_MASTER_SELECT_MASK) <<
> > +		PORT_SYNC_MODE_MASTER_SELECT_SHIFT;
> > +	/* Enable Transcoder Port Sync */
> > +	trans_ddi_func_ctl2_val |= PORT_SYNC_MODE_ENABLE;
> > +
> > +	I915_WRITE(TRANS_DDI_FUNC_CTL2(crtc_state->cpu_transcoder),
> > +		   trans_ddi_func_ctl2_val);
> > +}
> > +
> >  static void intel_update_pipe_config(const struct intel_crtc_state *old_crtc_state,
> >  				     const struct intel_crtc_state *new_crtc_state)
> >  {
> > @@ -6494,6 +6537,9 @@ static void haswell_crtc_enable(struct intel_crtc_state *pipe_config,
> >  	if (!transcoder_is_dsi(cpu_transcoder))
> >  		intel_set_pipe_timings(pipe_config);
> >  
> > +	if (INTEL_GEN(dev_priv) >= 11)
> > +		icl_enable_trans_port_sync(pipe_config);
> > +
> >  	intel_set_pipe_src_size(pipe_config);
> >  
> >  	if (cpu_transcoder != TRANSCODER_EDP &&
> > -- 
> > 2.19.1
> 
> -- 
> Ville Syrjälä
> Intel
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