The comments can be more precise. Let's fix them.
Fixes: 6cb786f040ad ("media: uvcvideo: Auto-set UVC_QUIRK_MSXU_META")
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20250716-uvc-meta-followup-v2-1-d3c2b995af3d@xxxxxxxxxxxx
Signed-off-by: Hans de Goede <hansg@xxxxxxxxxx>
---
drivers/media/usb/uvc/uvc_metadata.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c
index 3b0b392895119bb6ac300fc40b89a7ea00e56b40..b0960f0553cfcb30b0036d2ad8877fafa225c6a4 100644
--- a/drivers/media/usb/uvc/uvc_metadata.c
+++ b/drivers/media/usb/uvc/uvc_metadata.c
@@ -196,7 +196,10 @@ static int uvc_meta_detect_msxu(struct uvc_device *dev)
if (!data)
return -ENOMEM;
- /* Check if the metadata is already enabled. */
+ /*
+ * Check if the metadata is already enabled, or if the device always
+ * returns metadata.
+ */
ret = uvc_query_ctrl(dev, UVC_GET_CUR, entity->id, dev->intfnum,
MSXU_CONTROL_METADATA, data, sizeof(*data));
if (ret)
@@ -208,9 +211,11 @@ static int uvc_meta_detect_msxu(struct uvc_device *dev)
}
/*
- * We have seen devices that require 1 to enable the metadata, others
- * requiring a value != 1 and others requiring a value >1. Luckily for
- * us, the value from GET_MAX seems to work all the time.
+ * Set the value of MSXU_CONTROL_METADATA to the value reported by
+ * GET_MAX to enable production of MSXU metadata. The GET_MAX request
+ * reports the maximum size of the metadata, if its value is 0 then MSXU
+ * metadata is not supported. For more information, see
+ * https://learn.microsoft.com/en-us/windows-hardware/drivers/stream/uvc-extensions-1-5#2229-metadata-control
*/
ret = uvc_query_ctrl(dev, UVC_GET_MAX, entity->id, dev->intfnum,
MSXU_CONTROL_METADATA, data, sizeof(*data));
--
2.51.0.rc1.167.g924127e9c0-goog
