Re: [PATCH 6/8] drm/i915/dp: add 128b/132b support to link status checks

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Jan 25, 2022 at 07:03:44PM +0200, Jani Nikula wrote:
> Abstract link status check to a function that takes 128b/132b and 8b/10b
> into account, and use it. Also dump link status on failures.
> 
> Cc: Uma Shankar <uma.shankar@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c       | 39 ++++++++++++++-----
>  .../drm/i915/display/intel_dp_link_training.c |  2 +-
>  .../drm/i915/display/intel_dp_link_training.h |  4 ++
>  3 files changed, 34 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 4d4579a301f6..80fedd0e6212 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3628,6 +3628,32 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
>  			    "Could not write test response to sink\n");
>  }
>  
> +static bool intel_dp_link_ok(struct intel_dp *intel_dp,
> +			     u8 link_status[DP_LINK_STATUS_SIZE])
> +{
> +	struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
> +	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
> +	bool uhbr = intel_dp->link_rate >= 1000000;
> +	bool ok;
> +
> +	if (uhbr)
> +		ok = drm_dp_128b132b_lane_channel_eq_done(link_status,
> +							  intel_dp->lane_count);

That will only check the eq done bits. I think we want to keep the
symbol locked checks as well.

> +	else
> +		ok = drm_dp_channel_eq_ok(link_status, intel_dp->lane_count);
> +
> +	if (ok)
> +		return true;
> +
> +	intel_dp_dump_link_status(intel_dp, DP_PHY_DPRX, link_status);
> +	drm_dbg_kms(&i915->drm,
> +		    "[ENCODER:%d:%s] %s link not ok, retraining\n",
> +		    encoder->base.base.id, encoder->base.name,
> +		    uhbr ? "128b/132b" : "8b/10b");
> +
> +	return false;
> +}
> +
>  static void
>  intel_dp_mst_hpd_irq(struct intel_dp *intel_dp, u8 *esi, u8 *ack)
>  {
> @@ -3658,14 +3684,7 @@ static bool intel_dp_mst_link_status(struct intel_dp *intel_dp)
>  		return false;
>  	}
>  
> -	if (!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count)) {
> -		drm_dbg_kms(&i915->drm,
> -			    "[ENCODER:%d:%s] channel EQ not ok, retraining\n",
> -			    encoder->base.base.id, encoder->base.name);
> -		return false;
> -	}
> -
> -	return true;
> +	return intel_dp_link_ok(intel_dp, link_status);
>  }
>  
>  /**
> @@ -3779,8 +3798,8 @@ intel_dp_needs_link_retrain(struct intel_dp *intel_dp)
>  					intel_dp->lane_count))
>  		return false;
>  
> -	/* Retrain if Channel EQ or CR not ok */
> -	return !drm_dp_channel_eq_ok(link_status, intel_dp->lane_count);
> +	/* Retrain if link not ok */
> +	return !intel_dp_link_ok(intel_dp, link_status);
>  }
>  
>  static bool intel_dp_has_connector(struct intel_dp *intel_dp,
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> index 8bb6a296f421..1e41a560204a 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> @@ -712,7 +712,7 @@ static bool intel_dp_adjust_request_changed(const struct intel_crtc_state *crtc_
>  	return false;
>  }
>  
> -static void
> +void
>  intel_dp_dump_link_status(struct intel_dp *intel_dp, enum drm_dp_phy dp_phy,
>  			  const u8 link_status[DP_LINK_STATUS_SIZE])
>  {
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.h b/drivers/gpu/drm/i915/display/intel_dp_link_training.h
> index dbfb15705aaa..dc1556b46b85 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.h
> @@ -29,6 +29,10 @@ void intel_dp_start_link_train(struct intel_dp *intel_dp,
>  void intel_dp_stop_link_train(struct intel_dp *intel_dp,
>  			      const struct intel_crtc_state *crtc_state);
>  
> +void
> +intel_dp_dump_link_status(struct intel_dp *intel_dp, enum drm_dp_phy dp_phy,
> +			  const u8 link_status[DP_LINK_STATUS_SIZE]);
> +
>  /* Get the TPSx symbol type of the value programmed to DP_TRAINING_PATTERN_SET */
>  static inline u8 intel_dp_training_pattern_symbol(u8 pattern)
>  {
> -- 
> 2.30.2

-- 
Ville Syrjälä
Intel