| Message ID | 20241128-uvc-readless-v5-1-cf16ed282af8@chromium.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | media: uvcvideo: Support partial control reads and minor changes | expand |
On Thu, Nov 28, 2024 at 08:53:41PM +0000, Ricardo Ribalda wrote: > Some cameras, like the ELMO MX-P3, do not return all the bytes > requested from a control if it can fit in less bytes. > Eg: Returning 0xab instead of 0x00ab. > usb 3-9: Failed to query (GET_DEF) UVC control 3 on unit 2: 1 (exp. 2). > > Extend the returned value from the camera and return it. > > Cc: stable@vger.kernel.org > Fixes: a763b9fb58be ("media: uvcvideo: Do not return positive errors in uvc_query_ctrl()") > Reviewed-by: Hans de Goede <hdegoede@redhat.com> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > --- > drivers/media/usb/uvc/uvc_video.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > index cd9c29532fb0..67f714bca417 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -79,6 +79,27 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, > if (likely(ret == size)) > return 0; > > + /* > + * Some devices return shorter USB control packets than expected if the > + * returned value can fit in less bytes. Zero all the bytes that the > + * device has not written. > + * > + * This quirk is applied to all controls, regardless of their data type. > + * Most controls are little-endian integers, in which case the missing > + * bytes become 0 MSBs. For other data types, a different heuristic > + * could be implemented if a device is found needing it. > + * > + * We exclude UVC_GET_INFO from the quirk. UVC_GET_LEN does not need > + * to be excluded because its size is always 1. > + */ > + if (ret > 0 && query != UVC_GET_INFO) { > + memset(data + ret, 0, size - ret); > + dev_warn_once(&dev->udev->dev, > + "UVC non compliance: %s control %u on unit %u returned %d bytes when we expected %u.\n", > + uvc_query_name(query), cs, unit, ret, size); > + return 0; > + } > + > if (ret != -EPIPE) { > dev_err(&dev->udev->dev, > "Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index cd9c29532fb0..67f714bca417 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -79,6 +79,27 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, if (likely(ret == size)) return 0; + /* + * Some devices return shorter USB control packets than expected if the + * returned value can fit in less bytes. Zero all the bytes that the + * device has not written. + * + * This quirk is applied to all controls, regardless of their data type. + * Most controls are little-endian integers, in which case the missing + * bytes become 0 MSBs. For other data types, a different heuristic + * could be implemented if a device is found needing it. + * + * We exclude UVC_GET_INFO from the quirk. UVC_GET_LEN does not need + * to be excluded because its size is always 1. + */ + if (ret > 0 && query != UVC_GET_INFO) { + memset(data + ret, 0, size - ret); + dev_warn_once(&dev->udev->dev, + "UVC non compliance: %s control %u on unit %u returned %d bytes when we expected %u.\n", + uvc_query_name(query), cs, unit, ret, size); + return 0; + } + if (ret != -EPIPE) { dev_err(&dev->udev->dev, "Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",
Some cameras, like the ELMO MX-P3, do not return all the bytes requested from a control if it can fit in less bytes. Eg: Returning 0xab instead of 0x00ab. usb 3-9: Failed to query (GET_DEF) UVC control 3 on unit 2: 1 (exp. 2). Extend the returned value from the camera and return it. Cc: stable@vger.kernel.org Fixes: a763b9fb58be ("media: uvcvideo: Do not return positive errors in uvc_query_ctrl()") Reviewed-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org> --- drivers/media/usb/uvc/uvc_video.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)