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| author | Ricardo Ribalda <ribalda@chromium.org> | 2024-11-28 20:53:41 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-02-17 10:05:35 +0100 |
| commit | ac7737ed9aee8daf5fff3334ea35abd8adbbd3e6 (patch) | |
| tree | b76564a541e46c24302a03f9a74e7e097d3858a0 | |
| parent | 4f534dd576b78498e775dc5e9dc4ef077b8b4110 (diff) | |
| download | linux-ac7737ed9aee8daf5fff3334ea35abd8adbbd3e6.tar.gz linux-ac7737ed9aee8daf5fff3334ea35abd8adbbd3e6.tar.bz2 linux-ac7737ed9aee8daf5fff3334ea35abd8adbbd3e6.zip | |
media: uvcvideo: Support partial control reads
commit f00ee2ca8da25ebccb8e19956d853c9055e2c8d0 upstream.
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>
Link: https://lore.kernel.org/r/20241128-uvc-readless-v5-1-cf16ed282af8@chromium.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/media/usb/uvc/uvc_video.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index e00f38dd07d9..d2fe01bcd209 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", |