Re: [PATCH v4 05/16] drm/vkms: Allow to configure multiple CRTCs via configfs

[Louis Chauvet <louis.chauvet@bootlin.com>]

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

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

> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> Co-developed-by: José Expósito <jose.exposito89@gmail.com>
> Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> ---
>   Documentation/gpu/vkms.rst           |  6 ++
>   drivers/gpu/drm/vkms/vkms_configfs.c | 85 ++++++++++++++++++++++++++++
>   2 files changed, 91 insertions(+)
> 
> diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
> index a87e0925bebb..e0699603ef53 100644
> --- a/Documentation/gpu/vkms.rst
> +++ b/Documentation/gpu/vkms.rst
> @@ -74,6 +74,7 @@ By default, the instance is disabled::
>   And directories are created for each configurable item of the display pipeline::
>   
>     tree /config/vkms/my-vkms
> +  ├── crtcs
>     ├── enabled
>     └── planes
>   
> @@ -89,6 +90,10 @@ Planes have 1 configurable attribute:
>   - type: Plane type: 0 overlay, 1 primary, 2 cursor (same values as those
>     exposed by the "type" property of a plane)
>   
> +Continue by creating one or more CRTCs::
> +
> +  sudo mkdir /config/vkms/my-vkms/crtcs/crtc0
> +
>   Once you are done configuring the VKMS instance, enable it::
>   
>     echo "1" | sudo tee /config/vkms/my-vkms/enabled
> @@ -100,6 +105,7 @@ Finally, you can remove the VKMS instance disabling it::
>   And removing the top level directory and its subdirectories::
>   
>     sudo rmdir /config/vkms/my-vkms/planes/*
> +  sudo rmdir /config/vkms/my-vkms/crtcs/*
>     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 398755127759..62a82366791d 100644
> --- a/drivers/gpu/drm/vkms/vkms_configfs.c
> +++ b/drivers/gpu/drm/vkms/vkms_configfs.c
> @@ -17,6 +17,7 @@ static bool is_configfs_registered;
>    * @group: Top level configuration group that represents a VKMS device.
>    * 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"
>    * @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
> @@ -25,6 +26,7 @@ static bool is_configfs_registered;
>   struct vkms_configfs_device {
>   	struct config_group group;
>   	struct config_group planes_group;
> +	struct config_group crtcs_group;
>   
>   	struct mutex lock;
>   	struct vkms_config *config;
> @@ -45,6 +47,20 @@ struct vkms_configfs_plane {
>   	struct vkms_config_plane *config;
>   };
>   
> +/**
> + * struct vkms_configfs_crtc - Configfs representation of a CRTC
> + *
> + * @group: Top level configuration group that represents a CRTC.
> + * Initialized when a new directory is created under "/config/vkms/crtcs"
> + * @dev: The vkms_configfs_device this CRTC belongs to
> + * @config: Configuration of the VKMS CRTC
> + */
> +struct vkms_configfs_crtc {
> +	struct config_group group;
> +	struct vkms_configfs_device *dev;
> +	struct vkms_config_crtc *config;
> +};
> +
>   #define device_item_to_vkms_configfs_device(item) \
>   	container_of(to_config_group((item)), struct vkms_configfs_device, \
>   		     group)
> @@ -55,6 +71,71 @@ struct vkms_configfs_plane {
>   #define plane_item_to_vkms_configfs_plane(item) \
>   	container_of(to_config_group((item)), struct vkms_configfs_plane, group)
>   
> +#define crtc_item_to_vkms_configfs_crtc(item) \
> +	container_of(to_config_group((item)), struct vkms_configfs_crtc, group)
> +
> +static void crtc_release(struct config_item *item)
> +{
> +	struct vkms_configfs_crtc *crtc;
> +	struct mutex *lock;
> +
> +	crtc = crtc_item_to_vkms_configfs_crtc(item);
> +	lock = &crtc->dev->lock;
> +
> +	scoped_guard(mutex, lock) {
> +		vkms_config_destroy_crtc(crtc->dev->config, crtc->config);
> +		kfree(crtc);
> +	}
> +}
> +
> +static struct configfs_item_operations crtc_item_operations = {
> +	.release	= &crtc_release,
> +};
> +
> +static const struct config_item_type crtc_item_type = {
> +	.ct_item_ops	= &crtc_item_operations,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
> +static struct config_group *make_crtc_group(struct config_group *group,
> +					    const char *name)
> +{
> +	struct vkms_configfs_device *dev;
> +	struct vkms_configfs_crtc *crtc;
> +
> +	dev = child_group_to_vkms_configfs_device(group);
> +
> +	scoped_guard(mutex, &dev->lock) {
> +		if (dev->enabled)
> +			return ERR_PTR(-EBUSY);
> +
> +		crtc = kzalloc(sizeof(*crtc), GFP_KERNEL);
> +		if (!crtc)
> +			return ERR_PTR(-ENOMEM);
> +
> +		crtc->dev = dev;
> +
> +		crtc->config = vkms_config_create_crtc(dev->config);
> +		if (IS_ERR(crtc->config)) {
> +			kfree(crtc);
> +			return ERR_CAST(crtc->config);
> +		}
> +
> +		config_group_init_type_name(&crtc->group, name, &crtc_item_type);
> +	}
> +
> +	return &crtc->group;
> +}
> +
> +static struct configfs_group_operations crtcs_group_operations = {
> +	.make_group	= &make_crtc_group,
> +};
> +
> +static const struct config_item_type crtc_group_type = {
> +	.ct_group_ops	= &crtcs_group_operations,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
>   static ssize_t plane_type_show(struct config_item *item, char *page)
>   {
>   	struct vkms_configfs_plane *plane;
> @@ -262,6 +343,10 @@ static struct config_group *make_device_group(struct config_group *group,
>   				    &plane_group_type);
>   	configfs_add_default_group(&dev->planes_group, &dev->group);
>   
> +	config_group_init_type_name(&dev->crtcs_group, "crtcs",
> +				    &crtc_group_type);
> +	configfs_add_default_group(&dev->crtcs_group, &dev->group);
> +
>   	return &dev->group;
>   }
>   

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