When the uvcvideo driver encounters a format descriptor with an unknown
format GUID, it creates a corresponding struct uvc_format instance with
the fcc field set to 0. Since commit 50459f103edf ("media: uvcvideo:
Remove format descriptions"), the driver relies on the V4L2 core to
provide the format description string, which the V4L2 core can't do
without a valid 4CC. This triggers a WARN_ON.
As a format with a zero 4CC can't be selected, it is unusable for
applications. Ignore the format completely without creating a uvc_format
instance, which fixes the warning.
Fixes: 50459f103edf ("media: uvcvideo: Remove format descriptions")
Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
drivers/media/usb/uvc/uvc_driver.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index de64c9d789fd..25b8199f4e82 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -251,14 +251,17 @@ static int uvc_parse_format(struct uvc_device *dev,
/* Find the format descriptor from its GUID. */
fmtdesc = uvc_format_by_guid(&buffer[5]);
- if (fmtdesc != NULL) {
- format->fcc = fmtdesc->fcc;
- } else {
+ if (!fmtdesc) {
+ /*
+ * Unknown video formats are not fatal errors, the
+ * caller will skip this descriptor.
+ */
dev_info(&streaming->intf->dev,
"Unknown video format %pUl\n", &buffer[5]);
- format->fcc = 0;
+ return 0;
}
+ format->fcc = fmtdesc->fcc;
format->bpp = buffer[21];
/*
@@ -689,6 +692,8 @@ static int uvc_parse_streaming(struct uvc_device *dev,
&interval, buffer, buflen);
if (ret < 0)
goto error;
+ if (!ret)
+ break;
frame += format->nframes;
format++;
--
Regards,
Laurent Pinchart
