[PATCH v4 08/16] drm/vkms: Allow to configure multiple encoders via configfs

[Louis Chauvet]

Le 07/04/2025 à 10:14, José Expósito a écrit :
> From: Louis Chauvet <louis.chauvet at bootlin.com>
> 
> Create a default subgroup at /config/vkms/encoders to allow to create as
> many encoders as required.

Reviewed-by: Louis Chauvet <louis.chauvet at bootlin.com>

> Signed-off-by: Louis Chauvet <louis.chauvet at bootlin.com>
> Co-developed-by: José Expósito <jose.exposito89 at gmail.com>
> Signed-off-by: José Expósito <jose.exposito89 at gmail.com>
> ---
>   Documentation/gpu/vkms.rst           |  6 ++
>   drivers/gpu/drm/vkms/vkms_configfs.c | 87 ++++++++++++++++++++++++++++
>   2 files changed, 93 insertions(+)
> 
> diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
> index 13b96837a266..e24767448775 100644
> --- a/Documentation/gpu/vkms.rst
> +++ b/Documentation/gpu/vkms.rst
> @@ -76,6 +76,7 @@ And directories are created for each configurable item of the display pipeline::
>     tree /config/vkms/my-vkms
>     ├── crtcs
>     ├── enabled
> +  ├── encoders
>     └── planes
>   
>   To add items to the display pipeline, create one or more directories under the
> @@ -98,6 +99,10 @@ CRTCs have 1 configurable attribute:
>   
>   - writeback: Enable or disable writeback connector support by writing 1 or 0
>   
> +Next, create one or more encoders::
> +
> +  sudo mkdir /config/vkms/my-vkms/encoders/encoder0
> +
>   To finish the configuration, link the different pipeline items::
>   
>     sudo ln -s /config/vkms/my-vkms/crtcs/crtc0 /config/vkms/my-vkms/planes/plane0/possible_crtcs
> @@ -119,6 +124,7 @@ And removing the top level directory and its subdirectories::
>     sudo rm /config/vkms/my-vkms/planes/*/possible_crtcs/*
>     sudo rmdir /config/vkms/my-vkms/planes/*
>     sudo rmdir /config/vkms/my-vkms/crtcs/*
> +  sudo rmdir /config/vkms/my-vkms/encoders/*
>     sudo rmdir /config/vkms/my-vkms
>   
>   Testing With IGT
> diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
> index 2cf97c2b6203..0df86e63570a 100644
> --- a/drivers/gpu/drm/vkms/vkms_configfs.c
> +++ b/drivers/gpu/drm/vkms/vkms_configfs.c
> @@ -18,6 +18,7 @@ static bool is_configfs_registered;
>    * Initialized when a new directory is created under "/config/vkms/"
>    * @planes_group: Default subgroup of @group at "/config/vkms/planes"
>    * @crtcs_group: Default subgroup of @group at "/config/vkms/crtcs"
> + * @encoders_group: Default subgroup of @group at "/config/vkms/encoders"
>    * @lock: Lock used to project concurrent access to the configuration attributes
>    * @config: Protected by @lock. Configuration of the VKMS device
>    * @enabled: Protected by @lock. The device is created or destroyed when this
> @@ -27,6 +28,7 @@ struct vkms_configfs_device {
>   	struct config_group group;
>   	struct config_group planes_group;
>   	struct config_group crtcs_group;
> +	struct config_group encoders_group;
>   
>   	struct mutex lock;
>   	struct vkms_config *config;
> @@ -63,6 +65,20 @@ struct vkms_configfs_crtc {
>   	struct vkms_config_crtc *config;
>   };
>   
> +/**
> + * struct vkms_configfs_encoder - Configfs representation of a encoder
> + *
> + * @group: Top level configuration group that represents a encoder.
> + * Initialized when a new directory is created under "/config/vkms/encoders"
> + * @dev: The vkms_configfs_device this encoder belongs to
> + * @config: Configuration of the VKMS encoder
> + */
> +struct vkms_configfs_encoder {
> +	struct config_group group;
> +	struct vkms_configfs_device *dev;
> +	struct vkms_config_encoder *config;
> +};
> +
>   #define device_item_to_vkms_configfs_device(item) \
>   	container_of(to_config_group((item)), struct vkms_configfs_device, \
>   		     group)
> @@ -80,6 +96,10 @@ struct vkms_configfs_crtc {
>   #define crtc_item_to_vkms_configfs_crtc(item) \
>   	container_of(to_config_group((item)), struct vkms_configfs_crtc, group)
>   
> +#define encoder_item_to_vkms_configfs_encoder(item) \
> +	container_of(to_config_group((item)), struct vkms_configfs_encoder, \
> +		     group)
> +
>   static ssize_t crtc_writeback_show(struct config_item *item, char *page)
>   {
>   	struct vkms_configfs_crtc *crtc;
> @@ -344,6 +364,69 @@ static const struct config_item_type plane_group_type = {
>   	.ct_owner	= THIS_MODULE,
>   };
>   
> +static void encoder_release(struct config_item *item)
> +{
> +	struct vkms_configfs_encoder *encoder;
> +	struct mutex *lock;
> +
> +	encoder = encoder_item_to_vkms_configfs_encoder(item);
> +	lock = &encoder->dev->lock;
> +
> +	scoped_guard(mutex, lock) {
> +		vkms_config_destroy_encoder(encoder->dev->config, encoder->config);
> +		kfree(encoder);
> +	}
> +}
> +
> +static struct configfs_item_operations encoder_item_operations = {
> +	.release	= &encoder_release,
> +};
> +
> +static const struct config_item_type encoder_item_type = {
> +	.ct_item_ops	= &encoder_item_operations,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
> +static struct config_group *make_encoder_group(struct config_group *group,
> +					       const char *name)
> +{
> +	struct vkms_configfs_device *dev;
> +	struct vkms_configfs_encoder *encoder;
> +
> +	dev = child_group_to_vkms_configfs_device(group);
> +
> +	scoped_guard(mutex, &dev->lock) {
> +		if (dev->enabled)
> +			return ERR_PTR(-EBUSY);
> +
> +		encoder = kzalloc(sizeof(*encoder), GFP_KERNEL);
> +		if (!encoder)
> +			return ERR_PTR(-ENOMEM);
> +
> +		encoder->dev = dev;
> +
> +		encoder->config = vkms_config_create_encoder(dev->config);
> +		if (IS_ERR(encoder->config)) {
> +			kfree(encoder);
> +			return ERR_CAST(encoder->config);
> +		}
> +
> +		config_group_init_type_name(&encoder->group, name,
> +					    &encoder_item_type);
> +	}
> +
> +	return &encoder->group;
> +}
> +
> +static struct configfs_group_operations encoders_group_operations = {
> +	.make_group	= &make_encoder_group,
> +};
> +
> +static const struct config_item_type encoder_group_type = {
> +	.ct_group_ops	= &encoders_group_operations,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
>   static ssize_t device_enabled_show(struct config_item *item, char *page)
>   {
>   	struct vkms_configfs_device *dev;
> @@ -447,6 +530,10 @@ static struct config_group *make_device_group(struct config_group *group,
>   				    &crtc_group_type);
>   	configfs_add_default_group(&dev->crtcs_group, &dev->group);
>   
> +	config_group_init_type_name(&dev->encoders_group, "encoders",
> +				    &encoder_group_type);
> +	configfs_add_default_group(&dev->encoders_group, &dev->group);
> +
>   	return &dev->group;
>   }
>   

-- 
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com