From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:44436 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752086AbaCYXBw (ORCPT ); Tue, 25 Mar 2014 19:01:52 -0400 From: Laurent Pinchart To: William Manley Cc: linux-media@vger.kernel.org Subject: Re: [PATCH v2] uvcvideo: Work around buggy Logitech C920 firmware Date: Wed, 26 Mar 2014 00:03:46 +0100 Message-ID: <3163919.oZbdpQdqrg@avalon> In-Reply-To: <533209A1.5090806@williammanley.net> References: <1394647711-25291-1-git-send-email-will@williammanley.net> <1394714328-29969-1-git-send-email-will@williammanley.net> <533209A1.5090806@williammanley.net> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: Hi William, On Tuesday 25 March 2014 22:56:33 William Manley wrote: > On 13/03/14 12:38, William Manley wrote: > > The uvcvideo webcam driver exposes the v4l2 control "Exposure (Absolute)" > > which allows the user to control the exposure time of the webcam, > > essentially controlling the brightness of the received image. By default > > the webcam automatically adjusts the exposure time automatically but the > > if you set the control "Exposure, Auto"="Manual Mode" the user can fix > > the exposure time. > > > > Unfortunately it seems that the Logitech C920 has a firmware bug where > > it will forget that it's in manual mode temporarily during initialisation. > > This means that the camera doesn't respect the exposure time that the user > > requested if they request it before starting to stream video. They end up > > with a video stream which is either too bright or too dark and must reset > > the controls after video starts streaming. > > > > This patch introduces the quirk UVC_QUIRK_RESTORE_CTRLS_ON_INIT which > > causes the cached controls to be re-uploaded to the camera immediately > > after initialising the camera. This quirk is applied to the C920 to work > > around this camera bug. > > > > Changes since patch v1: > > * Introduce quirk so workaround is only applied to the C920. > > > > Signed-off-by: William Manley > > Bump? Sorry, I haven't had the time to handle your patch yet. I'll try to do so on Thursday or Friday. -- Regards, Laurent Pinchart