linux-kernel - Re: NEC ND-4550A problems reading DVD-R

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Message-ID: <4D70F286.5040508@earthlink.net>
Date:	Fri, 04 Mar 2011 09:09:10 -0500
From:	Stephen Clark <sclark46@...thlink.net>
To:	Tejun Heo <tj@...nel.org>
CC:	Mark Lord <kernel@...savvy.com>, Krzysztof Halasa <khc@...waw.pl>,
	linux-ide@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>,
	linux-scsi@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
	James Bottomley <James.Bottomley@...senPartnership.com>
Subject: Re: NEC ND-4550A problems reading DVD-R

On 03/04/2011 06:07 AM, 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?
>
> Thanks.
>
>    
I don't see this as being any different than all the other obfuscated 
tunable values that already
exists. At least I could google or look around for a tunable and maybe 
change it myself instead of having to
patch the source.

-- 

"They that give up essential liberty to obtain temporary safety,
deserve neither liberty nor safety."  (Ben Franklin)

"The course of history shows that as a government grows, liberty
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