[PATCH 03/10] drm/client: Add drm_client_init_from_id()

Noralf Trønnes
2020-04-29T12:57:57Z

drm_client_init_from_id() provides a way for clients to add a client based
on the minor. drm_client_register() is changed to return whether it was
registered or not depending on the unplugged status of the DRM device.
Its only caller drm_fbdev_generic_setup() runs inside probe() so it
doesn't have to check.

v2:
- Move drm_client_modeset_set() to a separate patch with added functions.
- Previous version had drm_client_init_from_id() call
drm_client_register(). This put the client in a position where it could
receive hotplugs during init in addition to akward error paths. Instead
let drm_client_register() return status so clients can know if the DRM
device is gone or not.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
drivers/gpu/drm/drm_client.c | 48 +++++++++++++++++++++++++++++++++++-
include/drm/drm_client.h | 4 ++-
2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index b031b45aa8ef..cb5ee9f1ffaa 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -112,6 +112,40 @@ int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
}
EXPORT_SYMBOL(drm_client_init);

+/**
+ * drm_client_init_from_id - Initialise a DRM client
+ * @minor_id: DRM minor id
+ * @client: DRM client
+ * @name: Client name
+ * @funcs: DRM client functions (optional)
+ *
+ * This function looks up the drm_device using the minor id and initializes the client.
+ *
+ * See drm_client_init() and drm_client_register().
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_init_from_id(unsigned int minor_id, struct drm_client_dev *client,
+ const char *name, const struct drm_client_funcs *funcs)
+{
+ struct drm_minor *minor;
+ int ret;
+
+ minor = drm_minor_acquire(minor_id);
+ if (IS_ERR(minor))
+ return PTR_ERR(minor);
+
+ mutex_lock(&minor->dev->clientlist_mutex);
+ ret = drm_client_init(minor->dev, client, name, funcs);
+ mutex_unlock(&minor->dev->clientlist_mutex);
+
+ drm_minor_release(minor);
+
+ return ret;
+}
+EXPORT_SYMBOL(drm_client_init_from_id);
+
/**
* drm_client_register - Register client
* @client: DRM client
@@ -121,14 +155,26 @@ EXPORT_SYMBOL(drm_client_init);
* drm_client_register() it is no longer permissible to call drm_client_release()
* directly (outside the unregister callback), instead cleanup will happen
* automatically on driver unload.
+ *
+ * Returns:
+ * True if the client has been registered, false if the DRM device has already
+ * been unregistered.
*/
-void drm_client_register(struct drm_client_dev *client)
+bool drm_client_register(struct drm_client_dev *client)
{
struct drm_device *dev = client->dev;
+ int idx;
+
+ if (!drm_dev_enter(client->dev, &idx))
+ return false;

mutex_lock(&dev->clientlist_mutex);
list_add(&client->list, &dev->clientlist);
mutex_unlock(&dev->clientlist_mutex);
+
+ drm_dev_exit(idx);
+
+ return true;
}
EXPORT_SYMBOL(drm_client_register);

diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 3ed5dee899fd..bbb5689fa9a8 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -109,8 +109,10 @@ struct drm_client_dev {

int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
const char *name, const struct drm_client_funcs *funcs);
+int drm_client_init_from_id(unsigned int minor_id, struct drm_client_dev *client,
+ const char *name, const struct drm_client_funcs *funcs);
void drm_client_release(struct drm_client_dev *client);
-void drm_client_register(struct drm_client_dev *client);
+bool drm_client_register(struct drm_client_dev *client);

void drm_client_dev_unregister(struct drm_device *dev);
void drm_client_dev_hotplug(struct drm_device *dev);
--
2.23.0