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

[Jani Nikula <jani.nikula@intel.com>]

On Thu, 21 Mar 2019, Manasi Navare <manasi.d.navare@intel.com> 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.
>
> 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>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 59 ++++++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 9980a4ed8c9c..16b46a3cb3bd 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4009,6 +4009,62 @@ static void icl_set_pipe_chicken(struct intel_crtc *crtc)
>  	I915_WRITE(PIPE_CHICKEN(pipe), tmp);
>  }
>  
> +static void icl_set_transcoder_port_sync(struct intel_atomic_state *old_intel_state,
> +					 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);
> +	struct intel_crtc_state *genlock_crtc_state = NULL;
> +	enum transcoder genlock_transcoder;
> +	u32 trans_ddi_func_ctl2_val;
> +	u8 master_select;
> +
> +	/*
> +	 * Port Sync Mode cannot be enabled for DP MST
> +	 */
> +	if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST))
> +		return;
> +
> +	/*
> +	 * Configure the master select and enable Transcoder Port Sync for
> +	 * Slave CRTCs transcoder.
> +	 */
> +	if (!crtc_state->genlock_crtc)
> +		return;
> +
> +	genlock_crtc_state = intel_atomic_get_new_crtc_state(old_intel_state,
> +							     crtc_state->genlock_crtc);
> +	if (WARN_ON(!genlock_crtc_state))
> +		return;
> +
> +	genlock_transcoder = genlock_crtc_state->cpu_transcoder;
> +	switch (genlock_transcoder) {
> +	case TRANSCODER_A:
> +		master_select = 1;
> +		break;
> +	case TRANSCODER_B:
> +		master_select = 2;
> +		break;
> +	case TRANSCODER_C:
> +		master_select = 3;
> +		break;
> +	case TRANSCODER_EDP:
> +	default:
> +		master_select = 0;
> +		break;
> +	}
> +	/* Set the master select bits for Tranascoder Port Sync */
> +	trans_ddi_func_ctl2_val = I915_READ(TRANS_DDI_FUNC_CTL2(crtc_state->cpu_transcoder));
> +	trans_ddi_func_ctl2_val |= (PORT_SYNC_MODE_MASTER_SELECT(master_select) &
> +				    PORT_SYNC_MODE_MASTER_SELECT_MASK) <<
> +		PORT_SYNC_MODE_MASTER_SELECT_SHIFT;

This doesn't do what you think it does. ITYM,

	val = I915_READ();
        val &= ~FOO_MASK;
        val |= FOO_BAR;

Please actually use just "val" for the variable, the long name just
makes this all harder to read.

BR,
Jani.


> +	/* 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)
>  {
> @@ -5960,6 +6016,9 @@ 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_set_transcoder_port_sync(old_intel_state, pipe_config);
> +
>  	intel_set_pipe_src_size(pipe_config);
>  
>  	if (cpu_transcoder != TRANSCODER_EDP &&

-- 
Jani Nikula, Intel Open Source Graphics Center
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