From: Kieran Bingham <kieran.bingham@xxxxxxxxxxxxxxxx>
When utilising multiple instantiations of a UVC gadget on a composite
device, there is no clear method to link a particular configuration to
its respective video node.
Provide a means for identifying the correct video node by exposing the
name of the function configuration through sysfs.
Signed-off-by: Kieran Bingham <kieran.bingham@xxxxxxxxxxxxxxxx>
---
v2:
- Fix commit title (f_uvc -> uvc)
- Change identifier file name (now function_name)
- Document in ABI
.../ABI/testing/configfs-usb-gadget-uvc | 5 ++++
drivers/usb/gadget/function/f_uvc.c | 24 ++++++++++++++++++-
2 files changed, 28 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uvc b/Documentation/ABI/testing/configfs-usb-gadget-uvc
index 1ba0d0fda9c0..9281e2aa38df 100644
--- a/Documentation/ABI/testing/configfs-usb-gadget-uvc
+++ b/Documentation/ABI/testing/configfs-usb-gadget-uvc
@@ -263,3 +263,8 @@ Description: Specific streaming header descriptors
is connected
bmInfo - capabilities of this video streaming
interface
+
+What: /sys/class/udc/udc.name/device/gadget/video4linux/video.name/function_name
+Date: May 2018
+KernelVersion: 4.19
+Description: UVC configfs function instance name
diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index d82cd61676d3..c8627cc698f8 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -421,10 +421,21 @@ uvc_function_disconnect(struct uvc_device *uvc)
* USB probe and disconnect
*/
+static ssize_t function_name_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct uvc_device *uvc = dev_get_drvdata(dev);
+
+ return sprintf(buf, "%s\n", uvc->func.fi->group.cg_item.ci_name);
+}
+
+static DEVICE_ATTR_RO(function_name);
+
static int
uvc_register_video(struct uvc_device *uvc)
{
struct usb_composite_dev *cdev = uvc->func.config->cdev;
+ int ret;
/* TODO reference counting. */
uvc->vdev.v4l2_dev = &uvc->v4l2_dev;
@@ -437,7 +448,17 @@ uvc_register_video(struct uvc_device *uvc)
video_set_drvdata(&uvc->vdev, uvc);
- return video_register_device(&uvc->vdev, VFL_TYPE_GRABBER, -1);
+ ret = video_register_device(&uvc->vdev, VFL_TYPE_GRABBER, -1);
+ if (ret < 0)
+ return ret;
+
+ ret = device_create_file(&uvc->vdev.dev, &dev_attr_function_name);
+ if (ret < 0) {
+ video_unregister_device(&uvc->vdev);
+ return ret;
+ }
+
+ return 0;
}
#define UVC_COPY_DESCRIPTOR(mem, dst, desc) \
@@ -877,6 +898,7 @@ static void uvc_unbind(struct usb_configuration *c, struct usb_function *f)
INFO(cdev, "%s\n", __func__);
+ device_remove_file(&uvc->vdev.dev, &dev_attr_function_name);
video_unregister_device(&uvc->vdev);
v4l2_device_unregister(&uvc->v4l2_dev);
--
2.17.0
--
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