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drm/vkms: Allow to attach encoders and CRTCs via configfs

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Create a default subgroup at
/config/vkms/encoders/encoder/possible_crtcs that will contain symbolic
links to the possible CRTCs for the encoder.

Tested-by: Mark Yacoub <markyacoub@google.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@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>
Link: https://lore.kernel.org/r/20251016175618.10051-10-jose.exposito89@gmail.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
This commit is contained in:
Louis Chauvet 2025-10-16 19:56:11 +02:00 • committed by Luca Ceresoli
parent 67d8cf92e1
commit fad1138b23
2 changed files with 60 additions and 0 deletions
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2
Documentation/gpu/vkms.rst
View file

@ -106,6 +106,7 @@ Next, create one or more encoders::
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
sudo ln -s /config/vkms/my-vkms/crtcs/crtc0 /config/vkms/my-vkms/encoders/encoder0/possible_crtcs
Since at least one primary plane is required, make sure to set the right type::
@ -122,6 +123,7 @@ Finally, you can remove the VKMS instance disabling it::
And removing the top level directory and its subdirectories::
sudo rm /config/vkms/my-vkms/planes/*/possible_crtcs/*
sudo rm /config/vkms/my-vkms/encoders/*/possible_crtcs/*
sudo rmdir /config/vkms/my-vkms/planes/*
sudo rmdir /config/vkms/my-vkms/crtcs/*
sudo rmdir /config/vkms/my-vkms/encoders/*

58
drivers/gpu/drm/vkms/vkms_configfs.c
View file

@ -70,11 +70,13 @@ struct vkms_configfs_crtc {
*
* @group: Top level configuration group that represents a encoder.
* Initialized when a new directory is created under "/config/vkms/encoders"
* @possible_crtcs_group: Default subgroup of @group at "encoder/possible_crtcs"
* @dev: The vkms_configfs_device this encoder belongs to
* @config: Configuration of the VKMS encoder
*/
struct vkms_configfs_encoder {
struct config_group group;
struct config_group possible_crtcs_group;
struct vkms_configfs_device *dev;
struct vkms_config_encoder *config;
};
@ -100,6 +102,10 @@ struct vkms_configfs_encoder {
container_of(to_config_group((item)), struct vkms_configfs_encoder, \
group)
#define encoder_possible_crtcs_item_to_vkms_configfs_encoder(item) \
container_of(to_config_group((item)), struct vkms_configfs_encoder, \
possible_crtcs_group)
static ssize_t crtc_writeback_show(struct config_item *item, char *page)
{
struct vkms_configfs_crtc *crtc;
@ -364,6 +370,52 @@ static const struct config_item_type plane_group_type = {
.ct_owner = THIS_MODULE,
};
static int encoder_possible_crtcs_allow_link(struct config_item *src,
struct config_item *target)
{
struct vkms_configfs_encoder *encoder;
struct vkms_configfs_crtc *crtc;
int ret;
if (target->ci_type != &crtc_item_type)
return -EINVAL;
encoder = encoder_possible_crtcs_item_to_vkms_configfs_encoder(src);
crtc = crtc_item_to_vkms_configfs_crtc(target);
scoped_guard(mutex, &encoder->dev->lock) {
if (encoder->dev->enabled)
return -EBUSY;
ret = vkms_config_encoder_attach_crtc(encoder->config, crtc->config);
}
return ret;
}
static void encoder_possible_crtcs_drop_link(struct config_item *src,
struct config_item *target)
{
struct vkms_configfs_encoder *encoder;
struct vkms_configfs_crtc *crtc;
encoder = encoder_possible_crtcs_item_to_vkms_configfs_encoder(src);
crtc = crtc_item_to_vkms_configfs_crtc(target);
scoped_guard(mutex, &encoder->dev->lock)
vkms_config_encoder_detach_crtc(encoder->config, crtc->config);
}
static struct configfs_item_operations encoder_possible_crtcs_item_operations = {
.allow_link = encoder_possible_crtcs_allow_link,
.drop_link = encoder_possible_crtcs_drop_link,
};
static const struct config_item_type encoder_possible_crtcs_group_type = {
.ct_item_ops = &encoder_possible_crtcs_item_operations,
.ct_owner = THIS_MODULE,
};
static void encoder_release(struct config_item *item)
{
struct vkms_configfs_encoder *encoder;
@ -413,6 +465,12 @@ static struct config_group *make_encoder_group(struct config_group *group,
config_group_init_type_name(&encoder->group, name,
&encoder_item_type);
config_group_init_type_name(&encoder->possible_crtcs_group,
"possible_crtcs",
&encoder_possible_crtcs_group_type);
configfs_add_default_group(&encoder->possible_crtcs_group,
&encoder->group);
}
return &encoder->group;