From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F1373FD4; Mon, 14 Jul 2025 17:08:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752512895; cv=none; b=fenAcJ9h3+SXzQOkFTIdTE5ZylFTak+yayD3r9zvFOIx1rbZxAollodOma5aPO2ZThXpg7CAb9egtc17EmaxU7yPvwOWNuQ1Cxo8aQAAKdHIzjZ7yleapZTxnda9rKTemSxVnLEq9i/4fqqxytrA1e0IduMr5TZnbkBVx5It7X4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752512895; c=relaxed/simple; bh=9k/+fL/6ozQpVW7PA+MTn0NMNv3pLc8FRDELsEyuLrI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GRMxDoNRwdOSGaJvD5OX0AybXzSnRpR8c4O4hEMbqriwLLrHY8M+tjHjZDcDjGs4gusmUbRSIKhBBuStVJqy9Tv7K922VZoNf+/iKq0T4LigQEyRGGzqu5x1I4qUt1C4GAcaYQEQNo1rZR8uRZWAGCYjqhjLugqywVS/d7W+riw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=pD4CIn60; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="pD4CIn60" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 42E3C289; Mon, 14 Jul 2025 19:07:40 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1752512860; bh=9k/+fL/6ozQpVW7PA+MTn0NMNv3pLc8FRDELsEyuLrI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pD4CIn60PU1001RvQbsBRLkBWUWuzoOe8xfHYS6RZfZWn0tEAIAZO7v+k/8xg8aIi Kj2x4SNpuMCERKdJszF2x6HUPnZHj4y1Me2txLkFgY0YXDAaAhWnQ8ZstNj5GqUfzf yfkfmf/xiiJt835BW2PJ1SrLmCJtB09zrnLHDGek= Date: Mon, 14 Jul 2025 20:07:40 +0300 From: Laurent Pinchart To: Ricardo Ribalda Cc: Mauro Carvalho Chehab , Guennadi Liakhovetski , Greg Kroah-Hartman , Hans de Goede , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Subject: Re: [PATCH v8 4/5] media: uvcvideo: Introduce V4L2_META_FMT_UVC_MSXU_1_5 Message-ID: <20250714170740.GC20231@pendragon.ideasonboard.com> References: <20250707-uvc-meta-v8-0-ed17f8b1218b@chromium.org> <20250707-uvc-meta-v8-4-ed17f8b1218b@chromium.org> <20250714145935.GL8243@pendragon.ideasonboard.com> <20250714162700.GA20231@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Mon, Jul 14, 2025 at 06:42:14PM +0200, Ricardo Ribalda wrote: > On Mon, 14 Jul 2025 at 18:27, Laurent Pinchart wrote: > > On Mon, Jul 14, 2025 at 06:21:05PM +0200, Ricardo Ribalda wrote: > > > On Mon, 14 Jul 2025 at 17:00, Laurent Pinchart wrote: > > > > > > > > Hi Ricardo, > > > > > > > > A bit of a stupid question, or rather a question that I wonder why I > > > > didn't think of before. > > > > > > I believe we discussed this in the very beginning, when I just enabled > > > V4L2_META_FMT_D4XX for all the devices. > > > > Sorry if that was the case, it was a while ago. > > > > > We thought that it could break applications. Imagine an APP that can > > > work with D4XX but not with other formats: if it tries to parse MSXU > > > format it might crash. > > > > How so, if V4L2_META_FMT_D4XX and V4L2_META_FMT_UVC_MSXU_1_5 identify > > the same format ? > > D4XX uses vendor IDs from MSXU (0x80000000-2) [1]. There is no > guarantee that other vendors will collide with that ID. I assume you mean "will not collide" ? There's also no guarantee that different vendors implementing the MSXU won't use vendor-specific metadata with colliding IDs, is there ? > Also, we do not know how apps will behave with IDs that they do not > know or with sizes that they have not been tested with. The change won't cause any regression for those apps when using Intel D4xx devices. > [1] https://www.kernel.org/doc/html/v5.8/userspace-api/media/v4l/pixfmt-meta-d4xx.html#id8 > > > > > On Mon, Jul 07, 2025 at 06:34:04PM +0000, 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 to have the whole metadata payload 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 introduces a new format V4L2_META_FMT_UVC_MSXU_1_5, that is > > > > > identical to V4L2_META_FMT_D4XX. > > > > > > > > Wouldn't it be simpler for everybody to just > > > > > > > > #define V4L2_META_FMT_UVC_MSXU_1_5 v4l2_fourcc('D', '4', 'X', 'X') /* UVC MSXU metadata */ > > > > #define V4L2_META_FMT_D4XX V4L2_META_FMT_UVC_MSXU_1_5 /* For backward compatibility */ > > > > > > > > ? I'm a bit uncomfortable with committing to a UABI with two different > > > > 4CCs for the exact same format. > > > > > > > > > Let the user enable this format with a quirk for now. This way they can > > > > > test if their devices provide useful metadata without rebuilding the > > > > > kernel. They can later contribute patches to auto-quirk their devices. > > > > > We will also work in methods to auto-detect devices compatible with this > > > > > new metadata format. > > > > > > > > > > Suggested-by: Hans de Goede > > > > > Reviewed-by: Hans de Goede > > > > > Signed-off-by: Ricardo Ribalda > > > > > --- > > > > > .../userspace-api/media/v4l/meta-formats.rst | 1 + > > > > > .../media/v4l/metafmt-uvc-msxu-1-5.rst | 23 ++++++++++++++++++++++ > > > > > MAINTAINERS | 1 + > > > > > drivers/media/usb/uvc/uvc_metadata.c | 4 ++++ > > > > > drivers/media/usb/uvc/uvcvideo.h | 1 + > > > > > drivers/media/v4l2-core/v4l2-ioctl.c | 1 + > > > > > include/uapi/linux/videodev2.h | 1 + > > > > > 7 files changed, 32 insertions(+) > > > > > > > > > > diff --git a/Documentation/userspace-api/media/v4l/meta-formats.rst b/Documentation/userspace-api/media/v4l/meta-formats.rst > > > > > index bb6876cfc271e1a0543eee4209d6251e1a6a73cc..0de80328c36bf148051a19abe9e5241234ddfe5c 100644 > > > > > --- a/Documentation/userspace-api/media/v4l/meta-formats.rst > > > > > +++ b/Documentation/userspace-api/media/v4l/meta-formats.rst > > > > > @@ -20,6 +20,7 @@ These formats are used for the :ref:`metadata` interface only. > > > > > metafmt-pisp-fe > > > > > metafmt-rkisp1 > > > > > metafmt-uvc > > > > > + metafmt-uvc-msxu-1-5 > > > > > metafmt-vivid > > > > > metafmt-vsp1-hgo > > > > > metafmt-vsp1-hgt > > > > > diff --git a/Documentation/userspace-api/media/v4l/metafmt-uvc-msxu-1-5.rst b/Documentation/userspace-api/media/v4l/metafmt-uvc-msxu-1-5.rst > > > > > new file mode 100644 > > > > > index 0000000000000000000000000000000000000000..dd1c3076df243d770a13e7f6d07c3296a269e16a > > > > > --- /dev/null > > > > > +++ b/Documentation/userspace-api/media/v4l/metafmt-uvc-msxu-1-5.rst > > > > > @@ -0,0 +1,23 @@ > > > > > +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later > > > > > + > > > > > +.. _v4l2-meta-fmt-uvc-msxu-1-5: > > > > > + > > > > > +*********************************** > > > > > +V4L2_META_FMT_UVC_MSXU_1_5 ('UVCM') > > > > > +*********************************** > > > > > + > > > > > +Microsoft(R)'s UVC Payload Metadata. > > > > > + > > > > > + > > > > > +Description > > > > > +=========== > > > > > + > > > > > +V4L2_META_FMT_UVC_MSXU_1_5 buffers follow the metadata buffer layout of > > > > > +V4L2_META_FMT_UVC with the only difference that it includes all the UVC > > > > > +metadata in the `buffer[]` field, not just the first 2-12 bytes. > > > > > + > > > > > +The metadata format follows the specification from Microsoft(R) [1]. > > > > > + > > > > > +.. _1: > > > > > + > > > > > +[1] https://docs.microsoft.com/en-us/windows-hardware/drivers/stream/uvc-extensions-1-5 > > > > > diff --git a/MAINTAINERS b/MAINTAINERS > > > > > index 658543062bba3b7e600699d7271ffc89250ba7e5..fdde1d37ed2ef9058e3ea3417bec25afe454dfc0 100644 > > > > > --- a/MAINTAINERS > > > > > +++ b/MAINTAINERS > > > > > @@ -25827,6 +25827,7 @@ S: Maintained > > > > > W: http://www.ideasonboard.org/uvc/ > > > > > T: git git://linuxtv.org/media.git > > > > > F: Documentation/userspace-api/media/drivers/uvcvideo.rst > > > > > +F: Documentation/userspace-api/media/v4l/metafmt-uvc-msxu-1-5.rst > > > > > F: Documentation/userspace-api/media/v4l/metafmt-uvc.rst > > > > > F: drivers/media/common/uvc.c > > > > > F: drivers/media/usb/uvc/ > > > > > diff --git a/drivers/media/usb/uvc/uvc_metadata.c b/drivers/media/usb/uvc/uvc_metadata.c > > > > > index 4bcbc22f47e67c52baf6e133f240131ff3d32a03..77e03273d3cf6b00cac6ebb9b29b941f1cbfd9f7 100644 > > > > > --- a/drivers/media/usb/uvc/uvc_metadata.c > > > > > +++ b/drivers/media/usb/uvc/uvc_metadata.c > > > > > @@ -195,6 +195,10 @@ void uvc_meta_init(struct uvc_device *dev) > > > > > !WARN_ON(dev->info->meta_format == V4L2_META_FMT_UVC)) > > > > > dev->meta_formats[i++] = dev->info->meta_format; > > > > > > > > > > + if (dev->quirks & UVC_QUIRK_MSXU_META && > > > > > + !WARN_ON(dev->info->meta_format == V4L2_META_FMT_UVC_MSXU_1_5)) > > > > > + dev->meta_formats[i++] = V4L2_META_FMT_UVC_MSXU_1_5; > > > > > + > > > > > /* IMPORTANT: for new meta-formats update UVC_MAX_META_DATA_FORMATS. */ > > > > > dev->meta_formats[i++] = 0; > > > > > } > > > > > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h > > > > > index b3c094c6591e7a71fc00e1096bcf493a83f330ad..616adc417c62a58686beccbc440a5dfac0a2d588 100644 > > > > > --- a/drivers/media/usb/uvc/uvcvideo.h > > > > > +++ b/drivers/media/usb/uvc/uvcvideo.h > > > > > @@ -77,6 +77,7 @@ > > > > > #define UVC_QUIRK_DISABLE_AUTOSUSPEND 0x00008000 > > > > > #define UVC_QUIRK_INVALID_DEVICE_SOF 0x00010000 > > > > > #define UVC_QUIRK_MJPEG_NO_EOF 0x00020000 > > > > > +#define UVC_QUIRK_MSXU_META 0x00040000 > > > > > > > > > > /* Format flags */ > > > > > #define UVC_FMT_FLAG_COMPRESSED 0x00000001 > > > > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c > > > > > index be94a79b976e3de4eb957f5d2584ec6d4230469e..993b36417b4655456ce545cb42a41b55b98e4d6c 100644 > > > > > --- a/drivers/media/v4l2-core/v4l2-ioctl.c > > > > > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c > > > > > @@ -1463,6 +1463,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt) > > > > > case V4L2_META_FMT_VSP1_HGO: descr = "R-Car VSP1 1-D Histogram"; break; > > > > > case V4L2_META_FMT_VSP1_HGT: descr = "R-Car VSP1 2-D Histogram"; break; > > > > > case V4L2_META_FMT_UVC: descr = "UVC Payload Header Metadata"; break; > > > > > + case V4L2_META_FMT_UVC_MSXU_1_5: descr = "UVC MSXU Metadata"; break; > > > > > case V4L2_META_FMT_D4XX: descr = "Intel D4xx UVC Metadata"; break; > > > > > case V4L2_META_FMT_VIVID: descr = "Vivid Metadata"; break; > > > > > case V4L2_META_FMT_RK_ISP1_PARAMS: descr = "Rockchip ISP1 3A Parameters"; break; > > > > > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > > > > > index 6f7bd38dd5aa4b1b2084685512512a380d76a5e4..863bc5b7dec32303e852d7e9c3891011ce5a3d71 100644 > > > > > --- a/include/uapi/linux/videodev2.h > > > > > +++ b/include/uapi/linux/videodev2.h > > > > > @@ -867,6 +867,7 @@ struct v4l2_pix_format { > > > > > #define V4L2_META_FMT_VSP1_HGT v4l2_fourcc('V', 'S', 'P', 'T') /* R-Car VSP1 2-D Histogram */ > > > > > #define V4L2_META_FMT_UVC v4l2_fourcc('U', 'V', 'C', 'H') /* UVC Payload Header metadata */ > > > > > #define V4L2_META_FMT_D4XX v4l2_fourcc('D', '4', 'X', 'X') /* D4XX Payload Header metadata */ > > > > > +#define V4L2_META_FMT_UVC_MSXU_1_5 v4l2_fourcc('U', 'V', 'C', 'M') /* UVC MSXU metadata */ > > > > > #define V4L2_META_FMT_VIVID v4l2_fourcc('V', 'I', 'V', 'D') /* Vivid Metadata */ > > > > > > > > > > /* Vendor specific - used for RK_ISP1 camera sub-system */ -- Regards, Laurent Pinchart