linux-kernel - Re: [PATCH 1/3] Make the IDE DMA timeout modifiable

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Date:	Tue, 17 Jul 2007 18:18:37 +0400
From:	Sergei Shtylyov <sshtylyov@...mvista.com>
To:	Rogier Wolff <R.E.Wolff@...Wizard.nl>
Cc:	Mark Lord <liml@....ca>, Alan Cox <alan@...rguk.ukuu.org.uk>,
	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
	Suleiman Souhlal <ssouhlal@...ebsd.org>,
	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] Make the IDE DMA timeout modifiable

Hello.

Rogier Wolff wrote:

>>>  Ah, that makes sense -- during PIO interrupts happen a lot more often.
>>>20 secs still seem to be too much.

>>I don't think so, even for modern drives.
>>Figure 8-10 seconds max for spin-up,
>>plus 6-9 seconds to do a sector re-assignment
>>or retries on a bad block (a measured *real-life* value).

>>That adds up to 14-19 seconds, so 20 seconds is probably good.

>>Still, this does need to be adjustable for faster (CF) devices,
>>and slower (optical/tape) devices, rather than just a single
>>set of fixed timeout values.

> In real life, with real bad blocks on real harddrives, some harddrives
> take more than the DMA TIMEOUT time to read a single block, even without
> having to spin up. 

   Yeah, "shit happens".

> The current code then resets the drive, on which the drive reports
> "busy, not ready for command", and things go downhill from there. 

    You are clearly mixing things: this message is a result of retrying 
command in PIO mode (that fails because the drive is still busy), and then the 
drives are actually reset. If they keep being busy *after* that, all I'd say 
is dump them ASAP. ;-)

> 	Roger. 

MBR, Sergei
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