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

Commit Message

José Expósito Feb. 18, 2025, 5:08 p.m. UTC

Create a default subgroup at /config/vkms/encoders to allow to create as
many encoders as required.

Co-developed-by: Louis Chauvet <[e-mail]>
Signed-off-by: Louis Chauvet <[e-mail]>
Signed-off-by: José Expósito <[e-mail]>
---
 Documentation/gpu/vkms.rst           |  6 ++
 drivers/gpu/drm/vkms/vkms_configfs.c | 99 ++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)

Patch

diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index 3c9d72bdb65a..24f40128e8f3 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
@@ -97,6 +98,10 @@  CRTCs have 1 configurable attribute:
 
 - writeback: Enable or disable writeback connector support
 
+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
@@ -118,6 +123,7 @@  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 7d5ebdd45d53..d7efa50a3fba 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;
  * 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
@@ -26,6 +27,7 @@  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;
@@ -62,6 +64,20 @@  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)
@@ -79,6 +95,10 @@  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;
@@ -382,6 +402,81 @@  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;
+
+	mutex_lock(lock);
+	vkms_config_destroy_encoder(encoder->dev->config, encoder->config);
+	kfree(encoder);
+	mutex_unlock(lock);
+}
+
+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;
+	int ret;
+
+	dev = child_group_to_vkms_configfs_device(group);
+
+	mutex_lock(&dev->lock);
+
+	if (dev->enabled) {
+		ret = -EINVAL;
+		goto err_unlock;
+	}
+
+	encoder = kzalloc(sizeof(*encoder), GFP_KERNEL);
+	if (!encoder) {
+		ret = -ENOMEM;
+		goto err_unlock;
+	}
+
+	encoder->dev = dev;
+
+	encoder->config = vkms_config_create_encoder(dev->config);
+	if (IS_ERR(encoder->config)) {
+		ret = PTR_ERR(encoder->config);
+		goto err_free;
+	}
+
+	config_group_init_type_name(&encoder->group, name, &encoder_item_type);
+
+	mutex_unlock(&dev->lock);
+
+	return &encoder->group;
+
+err_free:
+	kfree(encoder);
+err_unlock:
+	mutex_unlock(&dev->lock);
+	return ERR_PTR(ret);
+}
+
+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;
@@ -495,6 +590,10 @@  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;
 }