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SubjectRe: [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

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