Re: [PATCH v3] drm/sysfs: Link DRM connectors to corresponding Type-C connectors

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Won Chung <wonchung@google.com>,
	wonchung@google.com, bleung@google.com, pmalani@chromium.org,
	heikki.krogerus@linux.intel.com, imre.deak@intel.com,
	maarten.lankhorst@linux.intel.com, mripard@kernel.org,
	tzimmermann@suse.de, airlied@linux.ie, airlied@gmail.com,
	daniel@ffwll.ch, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] drm/sysfs: Link DRM connectors to corresponding Type-C connectors
Date: Tue, 08 Nov 2022 11:00:45 +0200	[thread overview]
Message-ID: <87k045akhu.fsf@intel.com> (raw)
In-Reply-To: <20221027212854.1083686-1-wonchung@google.com>

On Thu, 27 Oct 2022, Won Chung <wonchung@google.com> wrote:
> Create a symlink pointing to USB Type-C connector for DRM connectors
> when they are created. The link will be created only if the firmware is
> able to describe the connection beween the two connectors.

The commit messages should explain the *why*.

BR,
Jani.

>
> Signed-off-by: Won Chung <wonchung@google.com>
> Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> ---
> Changes from v2:
> - Resending the patch to dri-devel list
>
> Changes from v1:
> - Fix multiple lines to single line
>
>
>  drivers/gpu/drm/drm_sysfs.c | 40 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> index 430e00b16eec..6a9904fa9186 100644
> --- a/drivers/gpu/drm/drm_sysfs.c
> +++ b/drivers/gpu/drm/drm_sysfs.c
> @@ -11,12 +11,14 @@
>   */
>  
>  #include <linux/acpi.h>
> +#include <linux/component.h>
>  #include <linux/device.h>
>  #include <linux/err.h>
>  #include <linux/export.h>
>  #include <linux/gfp.h>
>  #include <linux/i2c.h>
>  #include <linux/kdev_t.h>
> +#include <linux/property.h>
>  #include <linux/slab.h>
>  
>  #include <drm/drm_connector.h>
> @@ -95,6 +97,34 @@ static char *drm_devnode(struct device *dev, umode_t *mode)
>  	return kasprintf(GFP_KERNEL, "dri/%s", dev_name(dev));
>  }
>  
> +static int typec_connector_bind(struct device *dev,
> +	struct device *typec_connector, void *data)
> +{
> +	int ret;
> +
> +	ret = sysfs_create_link(&dev->kobj, &typec_connector->kobj, "typec_connector");
> +	if (ret)
> +		return ret;
> +
> +	ret = sysfs_create_link(&typec_connector->kobj, &dev->kobj, "drm_connector");
> +	if (ret)
> +		sysfs_remove_link(&dev->kobj, "typec_connector");
> +
> +	return ret;
> +}
> +
> +static void typec_connector_unbind(struct device *dev,
> +	struct device *typec_connector, void *data)
> +{
> +	sysfs_remove_link(&typec_connector->kobj, "drm_connector");
> +	sysfs_remove_link(&dev->kobj, "typec_connector");
> +}
> +
> +static const struct component_ops typec_connector_ops = {
> +	.bind = typec_connector_bind,
> +	.unbind = typec_connector_unbind,
> +};
> +
>  static CLASS_ATTR_STRING(version, S_IRUGO, "drm 1.1.0 20060810");
>  
>  /**
> @@ -355,6 +385,13 @@ int drm_sysfs_connector_add(struct drm_connector *connector)
>  	if (connector->ddc)
>  		return sysfs_create_link(&connector->kdev->kobj,
>  				 &connector->ddc->dev.kobj, "ddc");
> +
> +	if (dev_fwnode(kdev)) {
> +		r = component_add(kdev, &typec_connector_ops);
> +		if (r)
> +			drm_err(dev, "failed to add component\n");
> +	}
> +
>  	return 0;
>  
>  err_free:
> @@ -367,6 +404,9 @@ void drm_sysfs_connector_remove(struct drm_connector *connector)
>  	if (!connector->kdev)
>  		return;
>  
> +	if (dev_fwnode(connector->kdev))
> +		component_del(connector->kdev, &typec_connector_ops);
> +
>  	if (connector->ddc)
>  		sysfs_remove_link(&connector->kdev->kobj, "ddc");

-- 
Jani Nikula, Intel Open Source Graphics Center