Re: [PATCH v5 01/24] drm: Include ddc adapter pointer in struct drm_connector

[Sam Ravnborg <sam-uyr5N9Q2VtJg9hUCZPvPmw@public.gmane.org>]

Hi Andrzej.

Patch looks good, but one kernel-doc detail.

On Wed, Jul 24, 2019 at 03:59:23PM +0200, Andrzej Pietrasiewicz wrote:
> Add generic code which creates symbolic links in sysfs, pointing to ddc
> interface used by a particular video output. For example:
> 
> ls -l /sys/class/drm/card0-HDMI-A-1/ddc
> lrwxrwxrwx 1 root root 0 Jun 24 10:42 /sys/class/drm/card0-HDMI-A-1/ddc \
> 	-> ../../../../soc/13880000.i2c/i2c-2
> 
> This makes it easy for user to associate a display with its ddc adapter
> and use e.g. ddcutil to control the chosen monitor.
> 
> This patch adds an i2c_adapter pointer to struct drm_connector. Particular
> drivers can then use it instead of using their own private instance. If a
> connector contains a ddc, then create a symbolic link in sysfs.
> 
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
> Acked-by: Daniel Vetter <daniel.vetter-/w4YWyX8dFk@public.gmane.org>
> Reviewed-by: Andrzej Hajda <a.hajda-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> ---
>  drivers/gpu/drm/drm_sysfs.c |  8 ++++++++
>  include/drm/drm_connector.h | 11 +++++++++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> index ad10810bc972..e962a9d45f7e 100644
> --- a/drivers/gpu/drm/drm_sysfs.c
> +++ b/drivers/gpu/drm/drm_sysfs.c
> @@ -14,6 +14,7 @@
>  #include <linux/err.h>
>  #include <linux/export.h>
>  #include <linux/gfp.h>
> +#include <linux/i2c.h>
>  #include <linux/kdev_t.h>
>  #include <linux/slab.h>
>  
> @@ -294,6 +295,9 @@ int drm_sysfs_connector_add(struct drm_connector *connector)
>  	/* Let userspace know we have a new connector */
>  	drm_sysfs_hotplug_event(dev);
>  
> +	if (connector->ddc)
> +		return sysfs_create_link(&connector->kdev->kobj,
> +				 &connector->ddc->dev.kobj, "ddc");
>  	return 0;
>  }
>  
> @@ -301,6 +305,10 @@ void drm_sysfs_connector_remove(struct drm_connector *connector)
>  {
>  	if (!connector->kdev)
>  		return;
> +
> +	if (connector->ddc)
> +		sysfs_remove_link(&connector->kdev->kobj, "ddc");
> +
>  	DRM_DEBUG("removing \"%s\" from sysfs\n",
>  		  connector->name);
>  
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 4c30d751487a..33a6fff85fdb 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -41,6 +41,7 @@ struct drm_property;
>  struct drm_property_blob;
>  struct drm_printer;
>  struct edid;
> +struct i2c_adapter;
>  
>  enum drm_connector_force {
>  	DRM_FORCE_UNSPECIFIED,
> @@ -1311,6 +1312,16 @@ struct drm_connector {
>  	 * [0]: progressive, [1]: interlaced
>  	 */
>  	int audio_latency[2];
> +
> +	/**
> +	 * @ddc: associated ddc adapter.
> +	 * A connector usually has its associated ddc adapter. If a driver uses
> +	 * this field, then an appropriate symbolic link is created in connector
> +	 * sysfs directory to make it easy for the user to tell which i2c
> +	 * adapter is for a particular display.
> +	 */
> +	struct i2c_adapter *ddc;

To help the reader could you add in the above a reference to
drm_connector_init_with_ddc() sp the reader is told how to init this
field.

Either add it in PATCH 2 - or merge patch 1 and 2.

	Sam

> +
>  	/**
>  	 * @null_edid_counter: track sinks that give us all zeros for the EDID.
>  	 * Needed to workaround some HW bugs where we get all 0s
> -- 
> 2.17.1