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 A5EB02C21FE for ; Thu, 19 Feb 2026 08:22:04 +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=1771489326; cv=none; b=Z+fZc2feRxJm/tvAIibRZvXz5vbnpTV/PDnqkruKizz9BAisyKtrEm5Qzn0AeJ+vlkDd87qR55RTMzhgbOGlqrKeaY1m3MQBOw+2SGUsBdBA910I/WCAfDf7xj3hvf5z3b22H0JZ9OsoR1GwyVryVSdKNIN0DKva8OO8m0BeBoo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771489326; c=relaxed/simple; bh=1r406bPgLG/GWEsM3ZEoRA9I/62MOfP7LHDHaKB1QU0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NJiezA9jajJqjFcmze9AMLFsJA/9sKs0i1kzidQwbRri9jciN3yMOA/BhLydffubXKLgqhWiiN1gUh1KZXW6dcXP/ZtqhprpolitIJajp/j3l3wsueLK/qrhYf/aiEChwH7eU6fVPEleH1icbYjxD2G2eYvbGEQ/5GdzVomHRlw= 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=PX9RQG7p; 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="PX9RQG7p" Received: from killaraus.ideasonboard.com (unknown [83.245.237.175]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 6C334371; Thu, 19 Feb 2026 09:21:09 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1771489269; bh=1r406bPgLG/GWEsM3ZEoRA9I/62MOfP7LHDHaKB1QU0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PX9RQG7pu08K9SYPLG9brDefrs/AvrdrbfX05GTOcB+uDobUMYlp9ElYby2Y3f7cb pRdDhpQXXchjWtysBM+6zKwTWQK8Jz8ljoS9oDkcEcYBWZDd8ik0E1OtGfoGmI2CiC 96aEkFV/Us9y9yyeEiCt/m3uuZMtleGd/XRv2+Rk= Date: Thu, 19 Feb 2026 09:21:57 +0100 From: Laurent Pinchart To: Itay Perl Cc: Ricardo Ribalda , Hans de Goede , "linux-media@vger.kernel.org" , Itay Chamiel Subject: Re: uvcvideo regression: loss of access to full UVC payload header for generic UVC devices since 6.17 Message-ID: <20260219082157.GD520738@killaraus.ideasonboard.com> References: <20260218222211.GE57525@killaraus.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Feb 19, 2026 at 06:03:49AM +0000, Itay Perl wrote: > ON 19 February 2026 06:22, Laurent Pinchart wrote: > > On Wed, Feb 18, 2026 at 11:56:28AM +0000, Itay Perl wrote: > > > On 18 February 2026 19:17, Ricardo Ribalda wrote: > > > > On Wed, 18 Feb 2026 at 11:59, Itay Perl wrote: > > > > > Would restoring the previous behavior be acceptable for compatibility? > > > > > Alternatively (or additionally), would it make sense to introduce a dedicated > > > > > metadata format that allows userspace to request the full UVC header for > > > > > generic devices? > > > > > > > > By any chance the device that you are using supports > > > > V4L2_META_FMT_UVC_MSXU_1_5 ? > > > > If the device exposes the UVC_MSXU_CONTROL_METADATA control, that > > > > format should be available, and it provices access to all the UVC > > > > header as you had before. > > > > > > > > Alternatively, if this is needed for a specific device you could send > > > > a patch adding the UVC_QUIRK_MSXU_META for that device. > > > > Would that work for you? > > > > > > My device is an internal development platform and does not have a public VID/PID > > > that could reasonably be added to the driver. > > > > > > I may be able to implement the MSXU control on the device side as a workaround, > > > but I'm concerned that this could cause issues when the device is used on a > > > Windows machine, which may expect the UVC header to follow a certain > > > format when MSXU is present. > > > > Does your device implement a vendor-specific metadata format ? > > Yes, the device uses a vendor-specific metadata format to attach > platform-specific data to each frame. This is the most straightforward way to > add per-frame metadata without otherwise affecting UVC functionality. We have > used this method successfully on Linux (using the 0-format hack) and on > Windows, where it required a registry configuration but was otherwise > supported. To support that device on Linux, the right way is to define a meta format (such as V4L2_META_FMT_UVC and V4L2_META_FMT_UVC_MSXU_1_5) and either add a VID:PID entry to the driver's uvc_ids[] array if the number of devices is small, or define an XU that advertises support for the format if you expect a larger number of devices. The metadata format needs to be documented. -- Regards, Laurent Pinchart