Re: [PATCH v8 1/4] drm/msm/dp: Add eDP support via aux_bus

Hi,

On Thu, Apr 21, 2022 at 7:37 AM Sankeerth Billakanti quic_sbillaka@quicinc.com wrote:

@@ -1530,6 +1532,61 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor) } }

+static int dp_display_get_next_bridge(struct msm_dp *dp) +{

•   int rc;
  

•   struct dp_display_private *dp_priv;
  

•   struct device_node *aux_bus;
  

•   struct device *dev;
  

•   dp_priv = container_of(dp, struct dp_display_private, dp_display);
  

•   dev = &dp_priv->pdev->dev;
  

•   aux_bus = of_get_child_by_name(dev->of_node, "aux-bus");
  

•   if (aux_bus && dp->is_edp) {
  

•           dp_display_host_init(dp_priv);
  

•           dp_catalog_ctrl_hpd_config(dp_priv->catalog);
  

•           dp_display_host_phy_init(dp_priv);
  

•           enable_irq(dp_priv->irq);
  

•           rc = devm_of_dp_aux_populate_ep_devices(dp_priv->aux);
  

I think a comment was requested above that line saying something like:

/* * The code below assumes that the panel will finish probing * by the time devm_of_dp_aux_populate_ep_devices() returns. * This isn't a great assumption since it will fail if the * panel driver is probed asynchronously but is the best we * can do without a bigger driver reorganization. */

•           of_node_put(aux_bus);
  

•           if (rc)
  

•                   goto edp_error;
  

•   } else if (dp->is_edp) {
  

•           DRM_ERROR("eDP aux_bus not found\n");
  

•           rc = -ENODEV;
  

•           goto error;
  

This goto doesn't add much. Just leave the above like it was in v7. return -ENODEV w/ no goto.

•   }
  

•   /*
  

•    * External bridges are mandatory for eDP interfaces: one has to
  

•    * provide at least an eDP panel (which gets wrapped into panel-bridge).
  

•    *
  

•    * For DisplayPort interfaces external bridges are optional, so
  

•    * silently ignore an error if one is not present (-ENODEV).
  

•    */
  

•   rc = dp_parser_find_next_bridge(dp_priv->parser);
  

•   if (rc && dp->is_edp) {
  

•           DRM_ERROR("eDP: cannot find the next bridge, rc = %d\n", rc);
  

•           goto edp_error;
  

•   } else if (rc && rc != -ENODEV) {
  

•           DRM_ERROR("DP: cannot find the next bridge, rc = %d\n", rc);
  

•           goto error;
  

•   }
  

The above wouldn't be my favorite way of doing this. Instead, I would have written:

if (rc) { DRM_ERROR("Cannot find the next bridge, rc = %d\n", rc); goto err; } ...

err: if (dp->is_edp) { disable_irq(...); dp_display_host_phy_exit(...); dp_display_host_deinit(...); } return rc;

•   dp->next_bridge = dp_priv->parser->next_bridge;
  

•   return 0;
  

+edp_error:

•   disable_irq(dp_priv->irq);
  

•   dp_display_host_phy_exit(dp_priv);
  

•   dp_display_host_deinit(dp_priv);
  

+error:

•   return rc;
  

+}

int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev, struct drm_encoder *encoder) {

With the above fixes, I'd be happy enough for my Reviewed-by tag with the expectation that continued work will happen to continue cleaning this up.

-Doug