[Intel-gfx] [PATCH] drm/i915/display/debugfs: Add connector debugfs for "output_bpc"

[Jani Nikula]

On Tue, 29 Mar 2022, Bhanuprakash Modem <bhanuprakash.modem at intel.com> wrote:
> This new debugfs will expose the connector's max supported bpc
> and the bpc currently using. It is very useful for verifying
> whether we enter the correct output color depth from IGT.
>
> Example:
> cat /sys/kernel/debug/dri/0/DP-1/output_bpc
> Current: 8
> Maximum: 10
>
> V2: Add connector's max bpc to i915_display_info
>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Uma Shankar <uma.shankar at intel.com>
> Cc: Swati Sharma <swati2.sharma at intel.com>
> Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
> ---
>  .../drm/i915/display/intel_display_debugfs.c  | 46 +++++++++++++++++++
>  1 file changed, 46 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index c1e74a13a0828..694d27f3b109c 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -663,6 +663,8 @@ static void intel_connector_info(struct seq_file *m,
>  	seq_puts(m, "\tHDCP version: ");
>  	intel_hdcp_info(m, intel_connector);
>  
> +	seq_printf(m, "\tmax bpc: %u\n", connector->display_info.bpc);
> +
>  	intel_panel_info(m, intel_connector);
>  
>  	seq_printf(m, "\tmodes:\n");
> @@ -2275,6 +2277,47 @@ static const struct file_operations i915_dsc_bpp_fops = {
>  	.write = i915_dsc_bpp_write
>  };
>  
> +/*
> + * Returns the maximum output bpc for the connector.
> + * Example usage: cat /sys/kernel/debug/dri/0/DP-1/output_bpc
> + */
> +static int output_bpc_show(struct seq_file *m, void *data)
> +{
> +	struct drm_connector *connector = m->private;
> +	struct drm_device *dev = connector->dev;
> +	struct drm_crtc *crtc;
> +	struct intel_crtc_state *crtc_state;
> +	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
> +	int res;
> +
> +	if (!encoder)
> +		return -ENODEV;
> +
> +	res = drm_modeset_lock_single_interruptible(&dev->mode_config.connection_mutex);
> +	if (res)
> +		return res;
> +
> +	crtc = connector->state->crtc;
> +	if (connector->status != connector_status_connected || !crtc) {
> +		res = -ENODEV;
> +		goto unlock;
> +	}
> +
> +	crtc_state = to_intel_crtc_state(crtc->state);
> +	if (!crtc_state->hw.active)
> +		goto unlock;
> +
> +	seq_printf(m, "Current: %u\n", crtc_state->pipe_bpp / 3);
> +	seq_printf(m, "Maximum: %u\n", connector->display_info.bpc);
> +	res = 0;
> +
> +unlock:
> +	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +
> +	return res;
> +}
> +DEFINE_SHOW_ATTRIBUTE(output_bpc);

Looks like an excessive amount of code for a single value.

BR,
Jani.

> +
>  /**
>   * intel_connector_debugfs_add - add i915 specific connector debugfs files
>   * @connector: pointer to a registered drm_connector
> @@ -2330,6 +2373,9 @@ void intel_connector_debugfs_add(struct intel_connector *intel_connector)
>  	    connector->connector_type == DRM_MODE_CONNECTOR_HDMIB)
>  		debugfs_create_file("i915_lpsp_capability", 0444, root,
>  				    connector, &i915_lpsp_capability_fops);
> +
> +	debugfs_create_file("output_bpc", 0444, root,
> +			    connector, &output_bpc_fops);
>  }
>  
>  /**

-- 
Jani Nikula, Intel Open Source Graphics Center