Re: [PATCH v3 2/5] drm/i915: Add support for DP link training compliance

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

Jani,

I have addressed few comments you had on the previous set of patches
about validating the test lane count so I am checking it against
min and max lane count values. Also made the debug prints
less verbose.
Could you please review this patch?

Regards
Manasi

On Fri, Dec 09, 2016 at 04:32:57PM -0800, Manasi Navare wrote:
> This patch adds support to handle automated DP compliance
> link training test requests. This patch has been tested with
> Unigraf DPR-120 DP Compliance device for testing Link
> Training Compliance.
> After we get a short pulse Compliance test request, test
> request values are read and hotplug uevent is sent in order
> to trigger another modeset during which the pipe is configured
> and link is retrained and enabled for link parameters requested
> by the test.
> 
> v2:
> * Validate the test lane count before using it in
> intel_dp_compute_config (Jani Nikula)
> Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c  | 62 +++++++++++++++++++++++++++++++++++++---
>  drivers/gpu/drm/i915/intel_drv.h |  2 ++
>  2 files changed, 60 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index c1e107c..bbf8cdc 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -278,6 +278,21 @@ static int intel_dp_common_rates(struct intel_dp *intel_dp,
>  			       common_rates);
>  }
>  
> +static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
> +				    int *common_rates, int link_rate)
> +{
> +	int common_len;
> +	int index;
> +
> +	common_len = intel_dp_common_rates(intel_dp, common_rates);
> +	for (index = 0; index < common_len; index++) {
> +		if (link_rate == common_rates[common_len - index - 1])
> +			return common_len - index - 1;
> +	}
> +
> +	return -1;
> +}
> +
>  static enum drm_mode_status
>  intel_dp_mode_valid(struct drm_connector *connector,
>  		    struct drm_display_mode *mode)
> @@ -1544,6 +1559,7 @@ static int intel_dp_compute_bpp(struct intel_dp *intel_dp,
>  	/* Conveniently, the link BW constants become indices with a shift...*/
>  	int min_clock = 0;
>  	int max_clock;
> +	int link_rate_index;
>  	int bpp, mode_rate;
>  	int link_avail, link_clock;
>  	int common_rates[DP_MAX_SUPPORTED_RATES] = {};
> @@ -1585,6 +1601,17 @@ static int intel_dp_compute_bpp(struct intel_dp *intel_dp,
>  	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
>  		return false;
>  
> +	/* Use values requested by Compliance Test Request */
> +	if (intel_dp->compliance.test_type == DP_TEST_LINK_TRAINING) {
> +		link_rate_index = intel_dp_link_rate_index(intel_dp,
> +							   common_rates,
> +							   drm_dp_bw_code_to_link_rate(intel_dp->compliance.test_link_rate));
> +		if (link_rate_index >= 0)
> +			min_clock = max_clock = link_rate_index;
> +		if (min_lane_count <= intel_dp->compliance.test_lane_count
> +		    && intel_dp->compliance.test_lane_count >= max_lane_count)
> +			min_lane_count = max_lane_count = intel_dp->compliance.test_lane_count;
> +	}
>  	DRM_DEBUG_KMS("DP link computation with max lane count %i "
>  		      "max bw %d pixel clock %iKHz\n",
>  		      max_lane_count, common_rates[max_clock],
> @@ -1632,6 +1659,7 @@ static int intel_dp_compute_bpp(struct intel_dp *intel_dp,
>  				}
>  			}
>  		}
> +
>  	}
>  
>  	return false;
> @@ -3804,6 +3832,27 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
>  static uint8_t intel_dp_autotest_link_training(struct intel_dp *intel_dp)
>  {
>  	uint8_t test_result = DP_TEST_ACK;
> +	int status = 0;
> +	/* (DP CTS 1.2)
> +	 * 4.3.1.11
> +	 */
> +	/* Read the TEST_LANE_COUNT and TEST_LINK_RTAE fields (DP CTS 3.1.4) */
> +	status = drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_LANE_COUNT,
> +				  &intel_dp->compliance.test_lane_count);
> +
> +	if (status <= 0) {
> +		DRM_DEBUG_KMS("Lane count read failed\n");
> +		return 0;
> +	}
> +	intel_dp->compliance.test_lane_count &= DP_MAX_LANE_COUNT_MASK;
> +
> +	status = drm_dp_dpcd_readb(&intel_dp->aux, DP_TEST_LINK_RATE,
> +				   &intel_dp->compliance.test_link_rate);
> +	if (status <= 0) {
> +		DRM_DEBUG_KMS("Link Rate read failed\n");
> +		return 0;
> +	}
> +
>  	return test_result;
>  }
>  
> @@ -4018,9 +4067,8 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
>  	if (WARN_ON_ONCE(!intel_dp->lane_count))
>  		return;
>  
> -	/* if link training is requested we should perform it always */
> -	if ((intel_dp->compliance.test_type == DP_TEST_LINK_TRAINING) ||
> -	    (!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count))) {
> +	/* Retrain if Channel EQ or CR not ok */
> +	if (!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count)) {
>  		DRM_DEBUG_KMS("%s: channel EQ not ok, retraining\n",
>  			      intel_encoder->base.name);
>  
> @@ -4045,6 +4093,7 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
>  intel_dp_short_pulse(struct intel_dp *intel_dp)
>  {
>  	struct drm_device *dev = intel_dp_to_dev(intel_dp);
> +	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
>  	u8 sink_irq_vector = 0;
>  	u8 old_sink_count = intel_dp->sink_count;
>  	bool ret;
> @@ -4078,7 +4127,7 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
>  				   sink_irq_vector);
>  
>  		if (sink_irq_vector & DP_AUTOMATED_TEST_REQUEST)
> -			DRM_DEBUG_DRIVER("Test request in short pulse not handled\n");
> +			intel_dp_handle_test_request(intel_dp);
>  		if (sink_irq_vector & (DP_CP_IRQ | DP_SINK_SPECIFIC_IRQ))
>  			DRM_DEBUG_DRIVER("CP or sink specific irq unhandled\n");
>  	}
> @@ -4086,6 +4135,11 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
>  	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
>  	intel_dp_check_link_status(intel_dp);
>  	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +	if (intel_dp->compliance.test_type == DP_TEST_LINK_TRAINING) {
> +		DRM_DEBUG_KMS("Link Training Compliance Test requested\n");
> +		/* Send a Hotplug Uevent to userspace to start modeset */
> +		drm_kms_helper_hotplug_event(intel_encoder->base.dev);
> +	}
>  
>  	return true;
>  }
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index f8c7046..dbd580a 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -892,6 +892,8 @@ struct intel_dp_compliance {
>  	unsigned long test_type;
>  	struct intel_dp_compliance_data test_data;
>  	bool test_active;
> +	u8 test_link_rate;
> +	u8 test_lane_count;
>  };
>  
>  struct intel_dp {
> -- 
> 1.9.1
> 
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx