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

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Date:   Thu, 22 Sep 2022 14:14:15 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Won Chung <wonchung@...gle.com>
Cc:     bleung@...gle.com, pmalani@...omium.org, imre.deak@...el.com,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...ux.ie, daniel@...ll.ch,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/sysfs: Link DRM connectors to corresponding Type-C
 connectors

Hi Won,

On Wed, Sep 21, 2022 at 06:26:37PM +0000, Won Chung 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.
> 
> Signed-off-by: Won Chung <wonchung@...gle.com>
> ---
>  drivers/gpu/drm/drm_sysfs.c | 42 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> index 430e00b16eec..8270b02e6783 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 +97,36 @@ 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");

One line is enough.

> +	if (ret)
> +		return ret;
> +
> +	ret = sysfs_create_link(&typec_connector->kobj, &dev->kobj,
> +		"drm_connector");

Ditto.

> +	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 +387,13 @@ 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 +406,9 @@ 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");
>  
> -- 
> 2.37.2.789.g6183377224-goog

-- 
heikki