Re: [PATCH] drm/i915: debugfs: Add support for probing DP sink CRC.

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

On Thu, 23 Jan 2014, Rodrigo Vivi <rodrigo.vivi@gmail.com> wrote:
> This debugfs interface will allow intel-gpu-tools test case
> to verify if screen has been updated properly on cases like PSR.
>
> v2: Accepted all Daniel's suggestions:
>     * grab modeset lock
>     * loop over connector and check DPMS on
>     * return errors
>     * use _eDP1 suffix for easy future extension
>     * don't cache crc_supported neither latest crc
>     * return crc as a full array and read it at once with aux.
>     * use 0 to turn TEST_SINK off.
>     * split the drm_helpers definitions in another patch.
>
> v3: Accepted 2 Damien's suggestion: remove h from printf hexa
>     and return ENODEV when eDP not present instead of EAGAIN.
>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 40 +++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_dp.c     | 30 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h    |  1 +
>  3 files changed, 71 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 74866bf..a1d29d1 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -1922,6 +1922,45 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
>  	return 0;
>  }
>  
> +static int i915_sink_crc(struct seq_file *m, void *data)
> +{
> +	struct drm_info_node *node = m->private;
> +	struct drm_device *dev = node->minor->dev;
> +	struct intel_encoder *encoder;
> +	struct intel_connector *connector;
> +	struct intel_dp *intel_dp = NULL;
> +	int ret;
> +	u8 crc[6];
> +
> +	drm_modeset_lock_all(dev);
> +	list_for_each_entry(connector, &dev->mode_config.connector_list,
> +			    base.head) {
> +
> +		if (connector->base.dpms != DRM_MODE_DPMS_ON)
> +			continue;
> +
> +		encoder = to_intel_encoder(connector->base.encoder);
> +		if (encoder->type != INTEL_OUTPUT_EDP)
> +			continue;
> +
> +		intel_dp = enc_to_intel_dp(&encoder->base);
> +
> +		ret = intel_dp_sink_crc(intel_dp, crc);
> +		if (ret) {
> +			drm_modeset_unlock_all(dev);
> +			return ret;
> +		}
> +
> +		seq_printf(m, "%02x%02x%02x%02x%02x%02x\n",
> +			   crc[0], crc[1], crc[2],
> +			   crc[3], crc[4], crc[5]);
> +		drm_modeset_unlock_all(dev);
> +		return 0;
> +	}
> +	drm_modeset_unlock_all(dev);
> +	return -ENODEV;

Hi Rodrigo, I really don't like sprinkling the drm_modeset_unlock_all()
on all paths. Please have one return path with the unlock and return
ret.

> +}
> +
>  static int i915_energy_uJ(struct seq_file *m, void *data)
>  {
>  	struct drm_info_node *node = m->private;
> @@ -3278,6 +3317,7 @@ static const struct drm_info_list i915_debugfs_list[] = {
>  	{"i915_dpio", i915_dpio_info, 0},
>  	{"i915_llc", i915_llc, 0},
>  	{"i915_edp_psr_status", i915_edp_psr_status, 0},
> +	{"i915_sink_crc_eDP1", i915_sink_crc, 0},
>  	{"i915_energy_uJ", i915_energy_uJ, 0},
>  	{"i915_pc8_status", i915_pc8_status, 0},
>  	{"i915_power_domain_info", i915_power_domain_info, 0},
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 7df5085..dc646ac 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -2846,6 +2846,36 @@ intel_dp_probe_oui(struct intel_dp *intel_dp)
>  	ironlake_edp_panel_vdd_off(intel_dp, false);
>  }
>  
> +int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
> +{
> +	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> +	struct drm_device *dev = intel_dig_port->base.base.dev;
> +	struct intel_crtc *intel_crtc =
> +		to_intel_crtc(intel_dig_port->base.base.crtc);
> +	u8 buf[1];
> +
> +	if (!intel_dp_aux_native_read_retry(intel_dp, DP_TEST_SINK_MISC, buf,
> +					    1))

The _retry variant is for when the sink might be in sleep. Is that the
case here?

> +		return -EAGAIN;
> +
> +	if (!(buf[0] & DP_TEST_CRC_SUPPORTED))
> +		return -ENOTTY;
> +
> +	if (!intel_dp_aux_native_write_1(intel_dp, DP_TEST_SINK,
> +					 DP_TEST_SINK_START))
> +		return -EAGAIN;
> +
> +	/* Wait 2 vblanks to be sure we will have the correct CRC value */
> +	intel_wait_for_vblank(dev, intel_crtc->pipe);
> +	intel_wait_for_vblank(dev, intel_crtc->pipe);
> +
> +	if (!intel_dp_aux_native_read_retry(intel_dp, DP_TEST_CRC_R_CR, crc, 6))
> +		return -EAGAIN;

_retry variant is definitely not needed here.

I wonder whether we should try to end test mode in the failure path.

BR,
Jani.


> +
> +	intel_dp_aux_native_write_1(intel_dp, DP_TEST_SINK, 0);
> +	return 0;
> +}
> +
>  static bool
>  intel_dp_get_sink_irq(struct intel_dp *intel_dp, u8 *sink_irq_vector)
>  {
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 9841f78..b19a43d 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -723,6 +723,7 @@ void intel_dp_stop_link_train(struct intel_dp *intel_dp);
>  void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
>  void intel_dp_encoder_destroy(struct drm_encoder *encoder);
>  void intel_dp_check_link_status(struct intel_dp *intel_dp);
> +int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc);
>  bool intel_dp_compute_config(struct intel_encoder *encoder,
>  			     struct intel_crtc_config *pipe_config);
>  bool intel_dp_is_edp(struct drm_device *dev, enum port port);
> -- 
> 1.8.1.2
>
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-- 
Jani Nikula, Intel Open Source Technology Center