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List:       linux-ide
Subject:    Re: [PATCH ide] : Increase WAIT_DRQ to support slow CF cards
From:       Mark Lord <liml () rtr ! ca>
Date:       2009-10-31 13:56:26
Message-ID: 4AEC420A.9030502 () rtr ! ca
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Robert Hancock wrote:
..
> This has come up before:
> 
> http://marc.info/?l=linux-ide&m=123064513313466&w=2
> 
> I think this timeout should not even exist. libata has no such timeout 
> (only the overall command completion timeout), and I can't find any 
> reference in current ATA specs to the device being required to raise DRQ 
> in any particular amount of time.
..

The reason for the original (20ms, then 50ms) timeout was this text
from the ATA1 specification, long since outdated:

   -  Upon receipt of a Class 3 command, the drive sets BSY within 400 nsec,
      sets  up the sector buffer for a write operation, sets DRQ within 20
      msec, and clears BSY within 400 nsec of setting DRQ.

Cheers
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