Re: hdregs.h puts csfo at word 129 - wrong, that's vendor specific

[Brett Russ <russb@emc.com>]

This appears to have been dropped.  The last word 
(http://article.gmane.org/gmane.linux.ide/3588) was from Alan who said 
Andre would know the history.

Andre, can you help answer?

Thanks
BR

Brett Russ wrote:
> Jeff Garzik wrote:
> 
>> Chris Hann wrote:
>>
>>> ide-disk.c checks csfo bit 0 to see if the cache is available on a 
>>> device
>>> hdregs.h maps csfo to word 129 of the Identify Device information
>>> the latest ATA documentation, e00159r3 Mandatory IDENTIFY DEVICE 
>>> information, says words 129-159 are Vendor specific.
>>>
>>> Why is the driver switching on cache operations based on a word that 
>>> has nothing to do with cache?
>>
>>
>>
>> Good question...  I would guess that it's some pre-ATA4 legacy magic, 
>> but that's just a guess.
> 
> 
> I just checked the specs for ATA[134567] (didn't have 2) and all of them 
> show word 129 as vendor specific, as Chris found.
> 
> The code that's in libata-dev shows in idedisk_setup():
> 
>         /* write cache enabled? */
>         if ((id->csfo & 1) || (id->cfs_enable_1 & (1 << 5)))
>                 drive->wcache = 1;
> 
> 
> Bart, what's the point of the csfo bit check?  If it's specific to one 
> non-ATA compliant device shouldn't it be testing something else along 
> with that bit?
> 
> BR
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