From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: NEC ND-4550A problems reading DVD-R Date: Fri, 04 Mar 2011 23:16:46 +0100 Message-ID: <4D7164CE.80009@kernel.dk> References: <20110301080153.GA26074@htj.dyndns.org> <4D6CF92A.4020105@teksavvy.com> <4D6D151D.8030307@earthlink.net> <20110304110757.GJ20499@htj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:34858 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932693Ab1CDWQt (ORCPT ); Fri, 4 Mar 2011 17:16:49 -0500 In-Reply-To: <20110304110757.GJ20499@htj.dyndns.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Tejun Heo Cc: Stephen Clark , Mark Lord , Krzysztof Halasa , linux-ide@vger.kernel.org, lkml , linux-scsi@vger.kernel.org, James Bottomley On 2011-03-04 12:07, Tejun Heo wrote: > (cc'ing Jens and James) > > On Tue, Mar 01, 2011 at 10:47:41AM -0500, Stephen Clark wrote: >> On 03/01/2011 08:48 AM, Mark Lord wrote: >>> On 11-03-01 03:01 AM, Tejun Heo wrote: >>> .. >>>> I think that's determined by drivers/scsi/sr.h::SR_TIMEOUT which is >>>> hardcoded to be 30 seconds. Maybe it's better to move it to use the >>>> block parameter. Anyways, the drive actually takes longer than 30secs >>>> to recognize the media? >>> That slow behaviour is not uncommon, especially as drives struggle >>> to recognize various forms of copy-protected media (DVD-Video). >>> A longer default, or tuneable timeout, would help. >> >> I agree with Mark, this should be a user tuneable value. My 2006 LG >> dvd-rw frequently times out >> trying to identify the media. But after numerous timeout error >> messages it usually suceeds. > > I don't think it should be a user tunable value. It should be > something automatic. I mean, how many would know to go some cryptic > place and increase sr probing timeout? > > At the same time, increasing it for other cases is quite unattractive, > so it probably would be a good idea to only use higher timeout value > for the TUR right after media presence change event. > > Anyone interested in doing it? A higher timeout would be the easy fix. And unless there's a solid way to detect whether the drive is truly hung or just busy trying to grok the media, I think it's the only feasible solution. -- Jens Axboe