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

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

On Wed, Dec 05, 2018 at 06:03:08PM -0500, Lyude Paul wrote:
> 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@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@intel.com>
> > Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> > Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
> > Cc: Lyude Paul <lyude@redhat.com>
> > Signed-off-by: Manasi Navare <manasi.d.navare@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:

Cool will do and add your r-b
Thanks for the reviews!

Manasi

> 
> } else if (ret) {
> 	break;
> }
> 
> Just for clarity. With that change:
> 
> Reviewed-by: Lyude Paul <lyude@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
> 
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