Re: [PATCH v2 2/3] drm: Plumb debugfs_init through to panels

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Douglas,

Thank you for the patch.

On Fri, Feb 04, 2022 at 04:13:41PM -0800, Douglas Anderson wrote:
> We'd like panels to be able to add things to debugfs underneath the
> connector's directory. Let's plumb it through. A panel will be able to
> put things in a "panel" directory under the connector's
> directory. Note that debugfs is not ABI and so it's always possible
> that the location that the panel gets for its debugfs could change in
> the future.
> 
> NOTE: this currently only works if you're using a modern
> architecture. Specifically the plumbing relies on _both_
> drm_bridge_connector and drm_panel_bridge. If you're not using one or
> both of these things then things won't be plumbed through.
> 
> As a side effect of this change, drm_bridges can also get callbacks to
> put stuff underneath the connector's debugfs directory. At the moment
> all bridges in the chain have their debugfs_init() called with the
> connector's root directory.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
> 
> Changes in v2:
> - ("drm: Plumb debugfs_init through to panels") new for v2.
> 
>  drivers/gpu/drm/bridge/panel.c         | 12 ++++++++++++
>  drivers/gpu/drm/drm_bridge_connector.c | 15 +++++++++++++++
>  drivers/gpu/drm/drm_debugfs.c          |  3 +++
>  include/drm/drm_bridge.h               |  7 +++++++
>  include/drm/drm_connector.h            |  7 +++++++
>  include/drm/drm_panel.h                |  8 ++++++++
>  6 files changed, 52 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
> index b32295abd9e7..5be057575183 100644
> --- a/drivers/gpu/drm/bridge/panel.c
> +++ b/drivers/gpu/drm/bridge/panel.c
> @@ -138,6 +138,17 @@ static int panel_bridge_get_modes(struct drm_bridge *bridge,
>  	return drm_panel_get_modes(panel_bridge->panel, connector);
>  }
>  
> +static void panel_bridge_debugfs_init(struct drm_bridge *bridge,
> +				      struct dentry *root)
> +{
> +	struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge);
> +	struct drm_panel *panel = panel_bridge->panel;
> +
> +	root = debugfs_create_dir("panel", root);
> +	if (panel->funcs->debugfs_init)
> +		panel->funcs->debugfs_init(panel, root);
> +}
> +
>  static const struct drm_bridge_funcs panel_bridge_bridge_funcs = {
>  	.attach = panel_bridge_attach,
>  	.detach = panel_bridge_detach,
> @@ -150,6 +161,7 @@ static const struct drm_bridge_funcs panel_bridge_bridge_funcs = {
>  	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
>  	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
>  	.atomic_get_input_bus_fmts = drm_atomic_helper_bridge_propagate_bus_fmt,
> +	.debugfs_init = panel_bridge_debugfs_init,
>  };
>  
>  /**
> diff --git a/drivers/gpu/drm/drm_bridge_connector.c b/drivers/gpu/drm/drm_bridge_connector.c
> index 791379816837..60923cdfe8e1 100644
> --- a/drivers/gpu/drm/drm_bridge_connector.c
> +++ b/drivers/gpu/drm/drm_bridge_connector.c
> @@ -216,6 +216,20 @@ static void drm_bridge_connector_destroy(struct drm_connector *connector)
>  	kfree(bridge_connector);
>  }
>  
> +static void drm_bridge_connector_debugfs_init(struct drm_connector *connector,
> +					      struct dentry *root)
> +{
> +	struct drm_bridge_connector *bridge_connector =
> +		to_drm_bridge_connector(connector);
> +	struct drm_encoder *encoder = bridge_connector->encoder;
> +	struct drm_bridge *bridge;
> +
> +	list_for_each_entry(bridge, &encoder->bridge_chain, chain_node) {
> +		if (bridge->funcs->debugfs_init)
> +			bridge->funcs->debugfs_init(bridge, root);
> +	}
> +}
> +
>  static const struct drm_connector_funcs drm_bridge_connector_funcs = {
>  	.reset = drm_atomic_helper_connector_reset,
>  	.detect = drm_bridge_connector_detect,
> @@ -223,6 +237,7 @@ static const struct drm_connector_funcs drm_bridge_connector_funcs = {
>  	.destroy = drm_bridge_connector_destroy,
>  	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
>  	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +	.debugfs_init = drm_bridge_connector_debugfs_init,
>  };
>  
>  /* -----------------------------------------------------------------------------
> diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
> index b0a826489488..7f1b82dbaebb 100644
> --- a/drivers/gpu/drm/drm_debugfs.c
> +++ b/drivers/gpu/drm/drm_debugfs.c
> @@ -436,6 +436,9 @@ void drm_debugfs_connector_add(struct drm_connector *connector)
>  	/* vrr range */
>  	debugfs_create_file("vrr_range", S_IRUGO, root, connector,
>  			    &vrr_range_fops);
> +
> +	if (connector->funcs->debugfs_init)
> +		connector->funcs->debugfs_init(connector, root);
>  }
>  
>  void drm_debugfs_connector_remove(struct drm_connector *connector)
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index 061d87313fac..f27b4060faa2 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -649,6 +649,13 @@ struct drm_bridge_funcs {
>  	 * the DRM_BRIDGE_OP_HPD flag in their &drm_bridge->ops.
>  	 */
>  	void (*hpd_disable)(struct drm_bridge *bridge);
> +
> +	/**
> +	 * @debugfs_init:
> +	 *
> +	 * Allows bridges to create bridge-specific debugfs files.
> +	 */
> +	void (*debugfs_init)(struct drm_bridge *bridge, struct dentry *root);
>  };
>  
>  /**
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 64cf5f88c05b..54429dde744a 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -1142,6 +1142,13 @@ struct drm_connector_funcs {
>  	 * has been received from a source outside the display driver / device.
>  	 */
>  	void (*oob_hotplug_event)(struct drm_connector *connector);
> +
> +	/**
> +	 * @debugfs_init:
> +	 *
> +	 * Allows connectors to create connector-specific debugfs files.
> +	 */
> +	void (*debugfs_init)(struct drm_connector *connector, struct dentry *root);
>  };
>  
>  /**
> diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
> index 4602f833eb51..1ba2d424a53f 100644
> --- a/include/drm/drm_panel.h
> +++ b/include/drm/drm_panel.h
> @@ -29,6 +29,7 @@
>  #include <linux/list.h>
>  
>  struct backlight_device;
> +struct dentry;
>  struct device_node;
>  struct drm_connector;
>  struct drm_device;
> @@ -125,6 +126,13 @@ struct drm_panel_funcs {
>  	 */
>  	int (*get_timings)(struct drm_panel *panel, unsigned int num_timings,
>  			   struct display_timing *timings);
> +
> +	/**
> +	 * @debugfs_init:
> +	 *
> +	 * Allows panels to create panels-specific debugfs files.
> +	 */
> +	void (*debugfs_init)(struct drm_panel *panel, struct dentry *root);
>  };
>  
>  /**

-- 
Regards,

Laurent Pinchart