[Intel-gfx] [PATCH v7] drm/i915/dsc: Add Per connector debugfs node for DSC support/enable

[Lyude Paul]

On Wed, 2018-12-05 at 14:57 -0800, Manasi Navare wrote:
> DSC can be supported per DP connector. This patch adds a per connector
> debugfs node to expose DSC support capability by the kernel.
> The same node can be used from userspace to force DSC enable.
> 
> force_dsc_en written through this debugfs node is used to force
> DSC even for lower resolutions.
> 
> Credits to Ville Syrjala for suggesting the proper locks to be used
> and to Lyude Paul for explaining how to use them in this context
> 
> v7:
> * Get crtc, crtc_state from connector atomic state
> and add proper locks and backoff (Ville, Chris Wilson, Lyude)
> (Suggested-by: Ville Syrjala <ville.syrjala at linux.intel.com>)
> * Use %zu for printing size_t variable (Lyude)
> v6:
> * Read fec_capable only for non edp (Manasi)
> v5:
> * Name it dsc sink support and also add
> fec support in the same node (Ville)
> v4:
> * Add missed connector_status check (Manasi)
> * Create i915_dsc_support node only for Gen >=10 (manasi)
> * Access intel_dp->dsc_dpcd only if its not NULL (Manasi)
> v3:
> * Combine Force_dsc_en with this patch (Ville)
> v2:
> * Use kstrtobool_from_user to avoid explicit error checking (Lyude)
> * Rebase on drm-tip (Manasi)
> 
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
> Cc: Anusha Srivatsa <anusha.srivatsa at intel.com>
> Cc: Lyude Paul <lyude at redhat.com>
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 107 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_dp.c     |   3 +-
>  drivers/gpu/drm/i915/intel_drv.h    |   3 +
>  3 files changed, 112 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c
> b/drivers/gpu/drm/i915/i915_debugfs.c
> index 129b9a6f8309..58f6636fffea 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -5086,6 +5086,106 @@ static int i915_hdcp_sink_capability_show(struct
> seq_file *m, void *data)
>  }
>  DEFINE_SHOW_ATTRIBUTE(i915_hdcp_sink_capability);
>  
> +static int i915_dsc_fec_support_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_dp *intel_dp;
> +	struct drm_modeset_acquire_ctx ctx;
> +	struct intel_crtc_state *crtc_state = NULL;
> +	int ret = 0;
> +	bool try_again = false;
> +
> +	drm_modeset_acquire_init(&ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
> +
> +	do {
> +		ret = drm_modeset_lock(&dev->mode_config.connection_mutex,
> +				       &ctx);
> +		if (ret) {
> +			ret = -EINTR;
> +			break;
> +		}
> +		crtc = connector->state->crtc;
> +		if (connector->status != connector_status_connected || !crtc)
> {
> +			ret = -ENODEV;
> +			break;
> +		}
> +		ret = drm_modeset_lock(&crtc->mutex, &ctx);
> +		if (ret == -EDEADLK) {
> +			ret = drm_modeset_backoff(&ctx);
> +			if (!ret) {
> +				try_again = true;
> +				continue;
> +			}
> +			break;
> +		}
> +		if (ret)
> +			break;
Maybe maybe make this:

} else if (ret) {
	break;
}

Just for clarity. With that change:

Reviewed-by: Lyude Paul <lyude at redhat.com>
> +
> +		intel_dp = enc_to_intel_dp(&intel_attached_encoder(connector)-
> >base);
> +		crtc_state = to_intel_crtc_state(crtc->state);
> +		seq_printf(m, "DSC_Enabled: %s\n",
> +			   yesno(crtc_state->dsc_params.compression_enable));
> +		if (intel_dp->dsc_dpcd)
> +			seq_printf(m, "DSC_Sink_Support: %s\n",
> +				   yesno(drm_dp_sink_supports_dsc(intel_dp-
> >dsc_dpcd)));
> +		if (!intel_dp_is_edp(intel_dp))
> +			seq_printf(m, "FEC_Sink_Support: %s\n",
> +				   yesno(drm_dp_sink_supports_fec(intel_dp-
> >fec_capable)));
> +	} while (try_again);
> +
> +	drm_modeset_drop_locks(&ctx);
> +	drm_modeset_acquire_fini(&ctx);
> +
> +	return ret;
> +}
> +
> +static ssize_t i915_dsc_fec_support_write(struct file *file,
> +					  const char __user *ubuf,
> +					  size_t len, loff_t *offp)
> +{
> +	bool dsc_enable = false;
> +	int ret;
> +	struct drm_connector *connector =
> +		((struct seq_file *)file->private_data)->private;
> +	struct intel_encoder *encoder = intel_attached_encoder(connector);
> +	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> +
> +	if (len == 0)
> +		return 0;
> +
> +	DRM_DEBUG_DRIVER("Copied %zu bytes from user to force DSC\n",
> +			 len);
> +
> +	ret = kstrtobool_from_user(ubuf, len, &dsc_enable);
> +	if (ret < 0)
> +		return ret;
> +
> +	DRM_DEBUG_DRIVER("Got %s for DSC Enable\n",
> +			 (dsc_enable) ? "true" : "false");
> +	intel_dp->force_dsc_en = dsc_enable;
> +
> +	*offp += len;
> +	return len;
> +}
> +
> +static int i915_dsc_fec_support_open(struct inode *inode,
> +				     struct file *file)
> +{
> +	return single_open(file, i915_dsc_fec_support_show,
> +			   inode->i_private);
> +}
> +
> +static const struct file_operations i915_dsc_fec_support_fops = {
> +	.owner = THIS_MODULE,
> +	.open = i915_dsc_fec_support_open,
> +	.read = seq_read,
> +	.llseek = seq_lseek,
> +	.release = single_release,
> +	.write = i915_dsc_fec_support_write
> +};
> +
>  /**
>   * i915_debugfs_connector_add - add i915 specific connector debugfs files
>   * @connector: pointer to a registered drm_connector
> @@ -5098,6 +5198,7 @@ DEFINE_SHOW_ATTRIBUTE(i915_hdcp_sink_capability);
>  int i915_debugfs_connector_add(struct drm_connector *connector)
>  {
>  	struct dentry *root = connector->debugfs_entry;
> +	struct drm_i915_private *dev_priv = to_i915(connector->dev);
>  
>  	/* The connector must have been registered beforehands. */
>  	if (!root)
> @@ -5122,5 +5223,11 @@ int i915_debugfs_connector_add(struct drm_connector
> *connector)
>  				    connector,
> &i915_hdcp_sink_capability_fops);
>  	}
>  
> +	if (INTEL_GEN(dev_priv) >= 10 &&
> +	    (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> +	     connector->connector_type == DRM_MODE_CONNECTOR_eDP))
> +		debugfs_create_file("i915_dsc_fec_support", S_IRUGO, root,
> +				    connector, &i915_dsc_fec_support_fops);
> +
>  	return 0;
>  }
> diff --git a/drivers/gpu/drm/i915/intel_dp.c
> b/drivers/gpu/drm/i915/intel_dp.c
> index a6907a1761ab..2e3097cae277 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -2051,7 +2051,8 @@ intel_dp_compute_link_config(struct intel_encoder
> *encoder,
>  							&limits);
>  
>  	/* enable compression if the mode doesn't fit available BW */
> -	if (!ret) {
> +	DRM_DEBUG_KMS("Force DSC en = %d\n", intel_dp->force_dsc_en);
> +	if (!ret || intel_dp->force_dsc_en) {
>  		if (!intel_dp_dsc_compute_config(intel_dp, pipe_config,
>  						 conn_state, &limits))
>  			return false;
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index f94a04b4ad87..0cedce438433 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1209,6 +1209,9 @@ struct intel_dp {
>  
>  	/* Displayport compliance testing */
>  	struct intel_dp_compliance compliance;
> +
> +	/* Display stream compression testing */
> +	bool force_dsc_en;
>  };
>  
>  enum lspcon_vendor {
-- 
Cheers,
	Lyude Paul