Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754441Ab3DYGck (ORCPT ); Thu, 25 Apr 2013 02:32:40 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:36711 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751213Ab3DYGci (ORCPT ); Thu, 25 Apr 2013 02:32:38 -0400 Date: Thu, 25 Apr 2013 14:33:06 +0800 From: Adam Lee To: Laurent Pinchart Cc: linux-kernel@vger.kernel.org, Matthew Garrett , Mauro Carvalho Chehab , "open list:USB VIDEO CLASS" Subject: Re: [PATCH] Revert "V4L/DVB: uvc: Enable USB autosuspend by default on uvcvideo" Message-ID: <20130425063306.GA20928@adam-laptop> Mail-Followup-To: Laurent Pinchart , linux-kernel@vger.kernel.org, Matthew Garrett , Mauro Carvalho Chehab , "open list:USB VIDEO CLASS" References: <1366790239-838-1-git-send-email-adam.lee@canonical.com> <6159110.qEtHHiJYtm@avalon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6159110.qEtHHiJYtm@avalon> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2094 Lines: 50 On Wed, Apr 24, 2013 at 11:17:52AM +0200, Laurent Pinchart wrote: > Hi Adam, > > Thanks for the patch. > > On Wednesday 24 April 2013 15:57:19 adam.lee@canonical.com wrote: > > From: Adam Lee > > > > This reverts commit 3dae8b41dc5651f8eb22cf310e8b116480ba25b7. > > > > 1, I do have a Chicony webcam, implements autosuspend in a broken way, > > make `poweroff` performs rebooting when its autosuspend enabled. > > > > 2, There are other webcams which don't support autosuspend too, like > > https://patchwork.kernel.org/patch/2356141/ > > > > 3, kernel removed USB_QUIRK_NO_AUTOSUSPEND in > > a691efa9888e71232dfb4088fb8a8304ffc7b0f9, because autosuspend is > > disabled by default. > > > > So, we need to disable autosuspend in uvcvideo, maintaining a quirk list > > only for uvcvideo is not a good idea. > > I've received very few bug reports about broken auto-suspend support in UVC > devices. Most of them could be solved by setting the RESET_RESUME quirk in USB > core, only the Creative Live! Cam Optia AF required a quirk in the uvcvideo > driver. I would thus rather use the available quirks (USB_QUIRK_RESET_RESUME > if possible, UVC_QUIRK_DISABLE_AUTOSUSPEND otherwise) than killing power > management for the vast majority of webcams that behave correctly. Here comes another one, integrated Chicony webcam 04f2:b39f, its autosuspend makes `poweroff` performs rebooting at the laptop I'm working on. I tried USB_QUIRK_RESET_RESUME, not helping. The quirks list will go longer and longer absolutely, do uvcvideo wanna maintain that? And why only uvcvideo do this in kernel space which against general USB module? I still suggest we disable it by default, people can enable it in udev just like almost all distroes do for udisks. Please consider about it. -- Regards, Adam Lee Hardware Enablement -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/