Hi Laurent
On 29/12/2022 02:05, Laurent Pinchart wrote:
Hi Dan,
Thank you for the patch.
On Mon, Nov 21, 2022 at 09:25:14AM +0000, Daniel Scally wrote:
Add .allow_link() and .drop_link() callbacks to allow users to link
an extension unit descriptor to a string descriptor.
A link seems weird to me for this. Wouldn't it be better to store the
name in uvcg_extension in a similar way that device or config strings
are handled in drievrs/usb/gadget/configfs.c ?
I think it's _easier_ that way but it conceptually makes more sense to
me like this. The primary problem I had with that method though is that
I couldn't see a good way to specify the language, if we do it that way.
Or do we just say we only support US English?
Signed-off-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx>
---
Changes in v2:
- New patch
drivers/usb/gadget/function/uvc_configfs.c | 60 ++++++++++++++++++++++
drivers/usb/gadget/function/uvc_configfs.h | 1 +
2 files changed, 61 insertions(+)
diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
index da2f70036993..5c51862150c4 100644
--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -1053,8 +1053,68 @@ static void uvcg_extension_release(struct config_item *item)
kfree(xu);
}
+static int uvcg_extension_allow_link(struct config_item *src, struct config_item *tgt)
+{
+ struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+ struct uvcg_extension *xu = to_uvcg_extension(src);
+ struct config_item *strings;
+ struct uvcg_string *string;
+ struct config_item *opts_item;
+ struct f_uvc_opts *opts;
+ int ret = 0;
+
+ mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+ /* Validate that the target of the link is an entry in strings/<langid> */
+ opts_item = src->ci_parent->ci_parent->ci_parent;
+
+ strings = config_group_find_item(to_config_group(opts_item), "strings");
+ if (!strings || tgt->ci_parent->ci_parent != strings) {
+ ret = -EINVAL;
+ goto put_strings;
+ }
+
+ string = to_uvcg_string(tgt);
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+
+ xu->string_descriptor_index = string->usb_string.id;
+
+ mutex_unlock(&opts->lock);
+
+put_strings:
+ config_item_put(strings);
+ mutex_unlock(su_mutex);
+
+ return ret;
+}
+
+static void uvcg_extension_drop_link(struct config_item *src, struct config_item *tgt)
+{
+ struct mutex *su_mutex = &src->ci_group->cg_subsys->su_mutex;
+ struct uvcg_extension *xu = to_uvcg_extension(src);
+ struct config_item *opts_item;
+ struct f_uvc_opts *opts;
+
+ mutex_lock(su_mutex); /* for navigating configfs hierarchy */
+
+ opts_item = src->ci_parent->ci_parent->ci_parent;
+ opts = to_f_uvc_opts(opts_item);
+
+ mutex_lock(&opts->lock);
+
+ xu->string_descriptor_index = 0;
+
+ mutex_unlock(&opts->lock);
+
+ mutex_unlock(su_mutex);
+}
+
static struct configfs_item_operations uvcg_extension_item_ops = {
.release = uvcg_extension_release,
+ .allow_link = uvcg_extension_allow_link,
+ .drop_link = uvcg_extension_drop_link,
};
static const struct config_item_type uvcg_extension_type = {
diff --git a/drivers/usb/gadget/function/uvc_configfs.h b/drivers/usb/gadget/function/uvc_configfs.h
index a714426a174a..e1308026aed6 100644
--- a/drivers/usb/gadget/function/uvc_configfs.h
+++ b/drivers/usb/gadget/function/uvc_configfs.h
@@ -183,6 +183,7 @@ struct uvcg_extension_unit_descriptor {
struct uvcg_extension {
struct config_item item;
struct list_head list;
+ u8 string_descriptor_index;
struct uvcg_extension_unit_descriptor desc;
};
