From: Guenter Roeck <linux@xxxxxxxxxxxx>
On a Webcam from Quanta, we see the following error.
usb 3-5: New USB device found, idVendor=0408, idProduct=30d2, bcdDevice= 0.03
usb 3-5: New USB device strings: Mfr=3, Product=1, SerialNumber=2
usb 3-5: Product: USB2.0 HD UVC WebCam
usb 3-5: Manufacturer: Quanta
usb 3-5: SerialNumber: 0x0001
...
uvcvideo: Found UVC 1.10 device USB2.0 HD UVC WebCam (0408:30d2)
uvcvideo: Failed to initialize entity for entity 5
uvcvideo: Failed to register entities (-22).
The Webcam reports an entity of type UVC_VC_EXTENSION_UNIT. It reports a
string index of '7' associated with that entity. The attempt to read that
string from the camera fails with error -32 (-EPIPE). usb_string() returns
that error, but it is ignored. As result, the entity name is empty. This
later causes v4l2_device_register_subdev() to return -EINVAL, and no
entities are registered as result.
While this appears to be a firmware problem with the camera, the kernel
should still handle the situation gracefully. To do that, check the return
value from usb_string(). If it reports an error, assign the entity's
default name.
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 215fb483efb0..828c443faaa9 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -879,10 +879,8 @@ static int uvc_parse_vendor_control(struct uvc_device *dev,
+ n;
memcpy(unit->extension.bmControls, &buffer[23+p], 2*n);
- if (buffer[24+p+2*n] != 0)
- usb_string(udev, buffer[24+p+2*n], unit->name,
- sizeof(unit->name));
- else
+ if (buffer[24+p+2*n] == 0 ||
+ usb_string(udev, buffer[24+p+2*n], unit->name, sizeof(unit->name)) < 0)
sprintf(unit->name, "Extension %u", buffer[3]);
list_add_tail(&unit->list, &dev->entities);
@@ -1006,15 +1004,15 @@ static int uvc_parse_standard_control(struct uvc_device *dev,
memcpy(term->media.bmTransportModes, &buffer[10+n], p);
}
- if (buffer[7] != 0)
- usb_string(udev, buffer[7], term->name,
- sizeof(term->name));
- else if (UVC_ENTITY_TYPE(term) == UVC_ITT_CAMERA)
- sprintf(term->name, "Camera %u", buffer[3]);
- else if (UVC_ENTITY_TYPE(term) == UVC_ITT_MEDIA_TRANSPORT_INPUT)
- sprintf(term->name, "Media %u", buffer[3]);
- else
- sprintf(term->name, "Input %u", buffer[3]);
+ if (buffer[7] == 0 ||
+ usb_string(udev, buffer[7], term->name, sizeof(term->name)) < 0) {
+ if (UVC_ENTITY_TYPE(term) == UVC_ITT_CAMERA)
+ sprintf(term->name, "Camera %u", buffer[3]);
+ if (UVC_ENTITY_TYPE(term) == UVC_ITT_MEDIA_TRANSPORT_INPUT)
+ sprintf(term->name, "Media %u", buffer[3]);
+ else
+ sprintf(term->name, "Input %u", buffer[3]);
+ }
list_add_tail(&term->list, &dev->entities);
break;
@@ -1047,10 +1045,8 @@ static int uvc_parse_standard_control(struct uvc_device *dev,
memcpy(term->baSourceID, &buffer[7], 1);
- if (buffer[8] != 0)
- usb_string(udev, buffer[8], term->name,
- sizeof(term->name));
- else
+ if (buffer[8] == 0 ||
+ usb_string(udev, buffer[8], term->name, sizeof(term->name)) < 0)
sprintf(term->name, "Output %u", buffer[3]);
list_add_tail(&term->list, &dev->entities);
@@ -1072,10 +1068,8 @@ static int uvc_parse_standard_control(struct uvc_device *dev,
memcpy(unit->baSourceID, &buffer[5], p);
- if (buffer[5+p] != 0)
- usb_string(udev, buffer[5+p], unit->name,
- sizeof(unit->name));
- else
+ if (buffer[5+p] == 0 ||
+ usb_string(udev, buffer[5+p], unit->name, sizeof(unit->name)) < 0)
sprintf(unit->name, "Selector %u", buffer[3]);
list_add_tail(&unit->list, &dev->entities);
@@ -1105,10 +1099,8 @@ static int uvc_parse_standard_control(struct uvc_device *dev,
if (dev->uvc_version >= 0x0110)
unit->processing.bmVideoStandards = buffer[9+n];
- if (buffer[8+n] != 0)
- usb_string(udev, buffer[8+n], unit->name,
- sizeof(unit->name));
- else
+ if (buffer[8+n] == 0 ||
+ usb_string(udev, buffer[8+n], unit->name, sizeof(unit->name)) < 0)
sprintf(unit->name, "Processing %u", buffer[3]);
list_add_tail(&unit->list, &dev->entities);
@@ -1136,10 +1128,8 @@ static int uvc_parse_standard_control(struct uvc_device *dev,
unit->extension.bmControls = (u8 *)unit + sizeof(*unit);
memcpy(unit->extension.bmControls, &buffer[23+p], n);
- if (buffer[23+p+n] != 0)
- usb_string(udev, buffer[23+p+n], unit->name,
- sizeof(unit->name));
- else
+ if (buffer[23+p+n] == 0 ||
+ usb_string(udev, buffer[23+p+n], unit->name, sizeof(unit->name)) < 0)
sprintf(unit->name, "Extension %u", buffer[3]);
list_add_tail(&unit->list, &dev->entities);
--
b4 0.11.0-dev-d93f8
