[PATCH v7 09/15] drm/i915: Add support for starting FRL training for HDMI2.1 via PCON

[Ville Syrjälä]

On Fri, Dec 18, 2020 at 04:07:17PM +0530, Ankit Nautiyal wrote:
> This patch adds functions to start FRL training for an HDMI2.1 sink,
> connected via a PCON as a DP branch device.
> This patch also adds a new structure for storing frl training related
> data, when FRL training is completed.
> 
> v2: As suggested by Uma Shankar:
> -renamed couple of variables for better clarity
> -tweaked the macros used for correct semantics for true/false
> -fixed other styling issues.
> 
> v3: Completed the TODO for condition for going to FRL mode.
> Modified the condition to determine the required FRL b/w
> based only on the Pcon and Sink's max FRL values.
> Moved the frl structure initialization to intel_dp_init_connector().
> 
> v4: Fixed typo in initialization of frl structure.
> 
> v5: Always use FRL if its possible, instead of enabling only for
> higher modes as done in v3.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> Reviewed-by: Uma Shankar <uma.shankar at intel.com> (v2)
> ---
>  .../drm/i915/display/intel_display_types.h    |   7 +
>  drivers/gpu/drm/i915/display/intel_dp.c       | 151 ++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_dp.h       |   2 +
>  3 files changed, 160 insertions(+)
<snip>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 0596d6c24e73..43027a6d5e5e 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3891,6 +3891,8 @@ static void intel_disable_dp(struct intel_atomic_state *state,
>  	intel_edp_backlight_off(old_conn_state);
>  	intel_dp_set_power(intel_dp, DP_SET_POWER_D3);
>  	intel_edp_panel_off(intel_dp);
> +	intel_dp->frl.is_trained = false;
> +	intel_dp->frl.trained_rate_gbps = 0;

This stuff looks rather misplaced (or missing from elsewhere). This code
doesn't even get executed on modern platforms.

<snip>
> +static int intel_dp_pcon_start_frl_training(struct intel_dp *intel_dp)
> +{
> +#define PCON_EXTENDED_TRAIN_MODE (1 > 0)
> +#define PCON_CONCURRENT_MODE (1 > 0)
> +#define PCON_SEQUENTIAL_MODE !PCON_CONCURRENT_MODE
> +#define PCON_NORMAL_TRAIN_MODE !PCON_EXTENDED_TRAIN_MODE

All of that looks like nonsense. What is it supposed to do?

> +#define TIMEOUT_FRL_READY_MS 500
> +#define TIMEOUT_HDMI_LINK_ACTIVE_MS 1000
> +
> +	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> +	int max_frl_bw, max_pcon_frl_bw, max_edid_frl_bw, ret;
> +	u8 max_frl_bw_mask = 0, frl_trained_mask;
> +	bool is_active;
> +
> +	ret = drm_dp_pcon_reset_frl_config(&intel_dp->aux);
> +	if (ret < 0)
> +		return ret;
> +
> +	max_pcon_frl_bw = intel_dp->dfp.pcon_max_frl_bw;
> +	drm_dbg(&i915->drm, "PCON max rate = %d Gbps\n", max_pcon_frl_bw);
> +
> +	max_edid_frl_bw = intel_dp_hdmi_sink_max_frl(intel_dp);
> +	drm_dbg(&i915->drm, "Sink max rate from EDID = %d Gbps\n", max_edid_frl_bw);
> +
> +	max_frl_bw = min(max_edid_frl_bw, max_pcon_frl_bw);
> +
> +	if (max_frl_bw <= 0)
> +		return -EINVAL;
> +
> +	ret = drm_dp_pcon_frl_prepare(&intel_dp->aux, false);
> +	if (ret < 0)
> +		return ret;
> +	/* Wait for PCON to be FRL Ready */
> +	wait_for(is_active = drm_dp_pcon_is_frl_ready(&intel_dp->aux) == true, TIMEOUT_FRL_READY_MS);
> +
> +	if (!is_active)
> +		return -ETIMEDOUT;
> +
> +	max_frl_bw_mask = intel_dp_pcon_set_frl_mask(max_frl_bw);
> +	ret = drm_dp_pcon_frl_configure_1(&intel_dp->aux, max_frl_bw, PCON_SEQUENTIAL_MODE);
> +	if (ret < 0)
> +		return ret;
> +	ret = drm_dp_pcon_frl_configure_2(&intel_dp->aux, max_frl_bw_mask, PCON_NORMAL_TRAIN_MODE);
> +	if (ret < 0)
> +		return ret;
> +	ret = drm_dp_pcon_frl_enable(&intel_dp->aux);
> +	if (ret < 0)
> +		return ret;
> +	/*
> +	 * Wait for FRL to be completed
> +	 * Check if the HDMI Link is up and active.
> +	 */
> +	wait_for(is_active = drm_dp_pcon_hdmi_link_active(&intel_dp->aux) == true, TIMEOUT_HDMI_LINK_ACTIVE_MS);
> +
> +	if (!is_active)
> +		return -ETIMEDOUT;
> +
> +	/* Verify HDMI Link configuration shows FRL Mode */
> +	if (DP_PCON_HDMI_MODE_FRL != drm_dp_pcon_hdmi_link_mode(&intel_dp->aux, &frl_trained_mask)) {
> +		drm_dbg(&i915->drm, "HDMI couldn't be trained in FRL Mode\n");
> +		return -EINVAL;
> +	}
> +	drm_dbg(&i915->drm, "MAX_FRL_MASK = %u, FRL_TRAINED_MASK = %u\n", max_frl_bw_mask, frl_trained_mask);
> +
> +	intel_dp->frl.trained_rate_gbps = intel_dp_pcon_get_frl_mask(frl_trained_mask);
> +	intel_dp->frl.is_trained = true;
> +	drm_dbg(&i915->drm, "FRL trained with : %d Gbps\n", intel_dp->frl.trained_rate_gbps);
> +
> +	return 0;
> +}
> +
> +static bool intel_dp_is_hdmi_2_1_sink(struct intel_dp *intel_dp)
> +{
> +	if (drm_dp_is_branch(intel_dp->dpcd) &&
> +	    intel_dp->has_hdmi_sink &&
> +	    intel_dp_hdmi_sink_max_frl(intel_dp) > 0)
> +		return true;
> +
> +	return false;
> +}
> +
> +void intel_dp_check_frl_training(struct intel_dp *intel_dp)
> +{
> +	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> +
> +	/* Always go for FRL training if supported */
> +	if (!intel_dp_is_hdmi_2_1_sink(intel_dp) ||
> +	    intel_dp->frl.is_trained)
> +		return;
> +
> +	if (intel_dp_pcon_start_frl_training(intel_dp) < 0) {
> +		int ret, mode;
> +
> +		drm_dbg(&dev_priv->drm, "Couldnt set FRL mode, continuing with TMDS mode\n");
> +		ret = drm_dp_pcon_reset_frl_config(&intel_dp->aux);
> +		mode = drm_dp_pcon_hdmi_link_mode(&intel_dp->aux, NULL);
> +
> +		if (ret < 0 || mode != DP_PCON_HDMI_MODE_TMDS)
> +			drm_dbg(&dev_priv->drm, "Issue with PCON, cannot set TMDS mode\n");
> +	} else {
> +		drm_dbg(&dev_priv->drm, "FRL training Completed\n");
> +	}
> +}
> +
>  static void
>  g4x_set_link_train(struct intel_dp *intel_dp,
>  		   const struct intel_crtc_state *crtc_state,
> @@ -8210,6 +8358,9 @@ intel_dp_init_connector(struct intel_digital_port *dig_port,
>  			       (temp & ~0xf) | 0xd);
>  	}
>  
> +	intel_dp->frl.is_trained = false;
> +	intel_dp->frl.trained_rate_gbps = 0;
> +
>  	return true;
>  
>  fail:
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
> index b871a09b6901..58b76a20459c 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp.h
> @@ -144,4 +144,6 @@ bool intel_dp_initial_fastset_check(struct intel_encoder *encoder,
>  void intel_dp_sync_state(struct intel_encoder *encoder,
>  			 const struct intel_crtc_state *crtc_state);
>  
> +void intel_dp_check_frl_training(struct intel_dp *intel_dp);
> +
>  #endif /* __INTEL_DP_H__ */
> -- 
> 2.17.1

-- 
Ville Syrjälä
Intel