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Message-ID: <eb5c43d2-4a7d-43e2-873f-79980c1a48f4@bootlin.com>
Date: Tue, 15 Apr 2025 14:11:24 +0200
From: Louis Chauvet <louis.chauvet@...tlin.com>
To: José Expósito <jose.exposito89@...il.com>
Cc: hamohammed.sa@...il.com, simona@...ll.ch, melissa.srw@...il.com,
maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de,
airlied@...il.com, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 05/16] drm/vkms: Allow to configure multiple CRTCs via
configfs
Le 07/04/2025 à 10:14, José Expósito a écrit :
> From: Louis Chauvet <louis.chauvet@...tlin.com>
>
> Create a default subgroup at /config/vkms/crtcs to allow to create as
> many CRTCs as required.
Reviewed-by: Louis Chauvet <louis.chauvet@...tlin.com>
> Signed-off-by: Louis Chauvet <louis.chauvet@...tlin.com>
> Co-developed-by: José Expósito <jose.exposito89@...il.com>
> Signed-off-by: José Expósito <jose.exposito89@...il.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
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