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 F1CF61DB522; Tue, 26 Nov 2024 18:06:27 +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=1732644390; cv=none; b=qaazW9VB3koJpkDqzkoYik4U+gr8ErLsnMe2fHBTjly+d1kqtyXLPMohMCRId+XAJylV0yNcWUfIq5Uju7XzhAd/aoK6/K3Sbx7p26jcEOKA9oGsU3wvYts+P+qxuKYRUi1X2pOk1TQYIlyRfusyARbror6l2rwXH9uZcDIqKvY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732644390; c=relaxed/simple; bh=KxsIqHPypuOykgv7rlUrLVVwdzbC6mnetSa+3Smk8lw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=THmzwZlit5DtFsx5SY7nyGehuNCRvCk1ZlbWaK75+Ke58Pljecs2YUmYzENLF4ylhz7P+jQ6YRcOfw5Smo4LwvFconVYW3cUlBTaqRDCipOd9Ld1WeyVj6tDwFTjs7o1NVpi6z1B7VyWR7HEHORZhpqkBRGQCiv7bu0/SRkOLTo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=kMaZzu/0; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="kMaZzu/0" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 52FD2B63; Tue, 26 Nov 2024 19:06:03 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1732644363; bh=KxsIqHPypuOykgv7rlUrLVVwdzbC6mnetSa+3Smk8lw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kMaZzu/0qI06eIdztvRxfkHCEFUDJlub44U5JyPS5SDW2rhULhBYHmoo6l0XR5HZC E7Qe/PlIR0fdnUTEBlv47d7j4ec0zcPzce0JfE2ViIqCLG71o0BiTRnjwofhPsC/7U z2QOT4I5QV1RFtHqwlrDwoWSZ1YxWhd33g3vBKEQ= Date: Tue, 26 Nov 2024 20:06:16 +0200 From: Laurent Pinchart To: Ricardo Ribalda Cc: Hans de Goede , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Sakari Ailus , stable@vger.kernel.org Subject: Re: [PATCH v4 1/2] media: uvcvideo: Support partial control reads Message-ID: <20241126180616.GL5461@pendragon.ideasonboard.com> References: <20241120-uvc-readless-v4-0-4672dbef3d46@chromium.org> <20241120-uvc-readless-v4-1-4672dbef3d46@chromium.org> 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: <20241120-uvc-readless-v4-1-4672dbef3d46@chromium.org> On Wed, Nov 20, 2024 at 03:26:19PM +0000, Ricardo Ribalda wrote: > 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 > Signed-off-by: Ricardo Ribalda > --- > drivers/media/usb/uvc/uvc_video.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > index cd9c29532fb0..482c4ceceaac 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -79,6 +79,22 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, > if (likely(ret == size)) > return 0; > > + /* > + * In UVC the data is usually represented in little-endian. I had a comment about this in the previous version, did you ignore it on purpose because you disagreed, or was it an oversight ? > + * Some devices return shorter USB control packets that expected if the > + * returned value can fit in less bytes. Zero all the bytes that the > + * device have not written. s/have/has/ And if you meant to start a new paragraph here, a blank line is missing. Otherwise, no need to break the line before 80 columns. > + * 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", -- Regards, Laurent Pinchart