Hi, On 3-Mar-25 5:22 PM, Ricardo Ribalda wrote: > On Mon, 3 Mar 2025 at 17:11, Laurent Pinchart > <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: >> >> On Mon, Mar 03, 2025 at 04:43:50PM +0100, Hans de Goede wrote: >>> On 3-Mar-25 16:13, Laurent Pinchart wrote: >>>> On Mon, Mar 03, 2025 at 03:47:51PM +0100, Hans de Goede wrote: >>>>> On 26-Feb-25 14:00, Ricardo Ribalda wrote: >>>>>> The UVC driver provides two metadata types V4L2_META_FMT_UVC, and >>>>>> V4L2_META_FMT_D4XX. The only difference between the two of them is that >>>>>> V4L2_META_FMT_UVC only copies PTS, SCR, size and flags, and >>>>>> V4L2_META_FMT_D4XX copies the whole metadata section. >>>>>> >>>>>> Now we only enable V4L2_META_FMT_D4XX for the Intel D4xx family of >>>>>> devices, but it is useful for any device where vendors include other >>>>>> metadata, such as the one described by Microsoft: >>>>>> - https://learn.microsoft.com/en-us/windows-hardware/drivers/stream/mf-capture-metadata >>>>>> >>>>>> This patch removes the UVC_INFO_META macro and enables >>>>>> V4L2_META_FMT_D4XX for every device. It also updates the documentation >>>>>> to reflect the change. >>>>>> >>>>>> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> >>>>> >>>>> Thanks, patch looks good to me: >>>>> >>>>> Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx> >>>> >>>> I don't quite agree, sorry. >>>> >>>> The reason why the current mechanism has been implemented this way is to >>>> ensure we have documentation for the metadata format of devices that >>>> expose metadata to userspace. >>>> >>>> If you want to expose the MS metadata, you can create a new metadata >>>> format for that, and enable it on devices that implement it. >>> >>> Looking at the long list of quirks this removes just for the D4xx >>> cameras I do not believe that having quirked based relaying of >>> which metadata fmt is used to userspace is something which scales >>> on the long term. Given the large amount of different UVC cameras >>> I really think we should move the USB VID:PID -> metadata format >>> mapping out of the kernel. >> >> If we can find a solution to ensure the metadata format gets documented, >> sure. > > MS default metadata is already documented: > https://learn.microsoft.com/en-us/windows-hardware/drivers/stream/mf-capture-metadata > > I would not worry too much about vendors abusing the metadata for > custom magic if that is your concern. > This would not work with Windows default driver, and that is what most > camera modules are tested against. > > >> >> When it comes to the MS metadata format, if I recall correctly, Ricardo >> said there's an XU with a known GUID to detect the metadata format. We >> therefore wouldn't need quirks. > > There is MXSU control > https://learn.microsoft.com/en-us/windows-hardware/drivers/stream/uvc-extensions-1-5 > But not all the vendors use it. Right so I actually already checked: https://learn.microsoft.com/en-us/windows-hardware/drivers/stream/uvc-extensions-1-5 yesterday before my udev hwdb suggestion I was wondering if there was a way to just get if MSmetadata was used from the camera itself. What I found was this: "UVC metadata is opt-in. Every IHV/OEM that needs metadata support must be enabled through a custom INF file." which lead me to the udev + hwdb suggestion. It is good to know that some cameras have a a way to fet this from a known XU GUID, but the official way seems to be to have per camera info in .inf files. So for Linux that would translate to having a list of vid:pid combinations somewhere. The question then becomes where do we put the vid:pid list and IMHO hwdb is much better (easier to maintain / update) then hardcoding this in the kernel. Regards, Hans
