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 D5C681AAE3B; Wed, 20 Nov 2024 14:05:37 +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=1732111539; cv=none; b=lTq6LlZt4343bKmjs3TFWZHFwW/ng/CgiFadEvhppX2+K4nSHEfzzWPe2VbTIZkUBh9TVoaT1oZcYLLsELBYoaneoyouARBlX/GDYyH3Hzh/nni0mAgP8HHYQBaQWv8OkY+WeDbgh7sen5abC3et4XS72+lYmAKgtfwcKm18il8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732111539; c=relaxed/simple; bh=vd3kzFSdbl2IkePtTWEbaOck39V/PY35YREvWDd9Dbk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=paEWBwG4kQ9mfzmwON7HXZw9lxfpRiWvI+MOBZ1qZKJAvDJ1cLYDSqNhOytgtkabkiShC/xqcJPZ9dph8Og1NvxmFnWJtJheTxP8kVf+/i/Ac1WYGpptaD+qL3fwf1s68qjQs2hwRIYHjz5fgYbO/KWuDqo7l0q4pdH6RlYLw08= 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=Q17L4aZU; 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="Q17L4aZU" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id B22CE55A; Wed, 20 Nov 2024 15:05:17 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1732111517; bh=vd3kzFSdbl2IkePtTWEbaOck39V/PY35YREvWDd9Dbk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Q17L4aZUuwLbMZwOFHxsV+SrY4/4w67FbIHv7GA3buMDLNqj/058HkfG7pJtmIJtM sGKsAVb4tQVdl/YF0Nyzj8jiBbEC+KsPK6VFhqdwE7yh065GSUZKNIbo36SOVBP5Yz 1V2crDAgfRWYU7/8Ycdv1TtoKJMrK2E3CqV7Gzq0= Date: Wed, 20 Nov 2024 16:05:26 +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 v3 1/2] media: uvcvideo: Support partial control reads Message-ID: <20241120140526.GW12409@pendragon.ideasonboard.com> References: <20241118-uvc-readless-v3-0-d97c1a3084d0@chromium.org> <20241118-uvc-readless-v3-1-d97c1a3084d0@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: <20241118-uvc-readless-v3-1-d97c1a3084d0@chromium.org> Hi Ricardo, Thank you for the patch. On Mon, Nov 18, 2024 at 05:16:51PM +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()") > Signed-off-by: Ricardo Ribalda > --- > drivers/media/usb/uvc/uvc_video.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > index cd9c29532fb0..e165850397a0 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -76,8 +76,22 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit, > > ret = __uvc_query_ctrl(dev, query, unit, intfnum, cs, data, size, > UVC_CTRL_CONTROL_TIMEOUT); > - if (likely(ret == size)) > + if (ret > 0) { > + if (size == ret) > + return 0; Why is this within the ret > 0 block ? I would write if (likely(ret == size)) return 0; if (ret > 0) { > + > + /* > + * In UVC the data is represented in little-endian by default. By default, or always ? > + * Some devices return shorter control packages that expected What's a "control package" ? I think you meants "than expected", not "that expected". > + * if the return value can fit in less bytes. > + * Zero all the bytes that the device have not written. > + */ Do we want to apply this workaround to GET_INFO and GET_LEN, or can we restrict it to GET_CUR, GET_MIN, GET_MAX and GET_RES ? > + 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, > -- Regards, Laurent Pinchart