Re: Linux v2.6.22-rc3

[Jeff Garzik]

Tejun Heo wrote:
> Most BIOSen, Windows and old IDE driver don't reset at all during
> probing.  They first issue IDENTIFY unconditionally, if that fails,
> IDENTIFY_PACKET.  From the beginning, libata has issued reset during

Not true for BIOS.  A large sub-section of BIOS (Phoenix and/or 
Award-based BIOSen) do SRST along with the Hale Landis device detection 
(ata_devchk in libata-core.c).  Ditto for several ATA vendor BIOS found 
on the card.

I'm about to dive into some heads-down RHEL backporting (whee), so I 
cannot look at the code in depth this weekend, but here are my basic 
thoughts:

* We knew there would be fallout from the new reset-sequence code, and 
this is clearly in that category.

* It worked before #reset-seq merge AFAICT, which implies the old method 
of probing -- which included SRST -- worked.

* If this was a major problem, I would think there would be a flood of 
bug reports for Fedora 7 (just released, and in testing w/ #reset-seq 
for a little while), since it is using libata for PATA as well as SATA. 
 So this, just this one bug report right?


I would go back and look at the differences in the low-level register 
bitbanging, and what specifically changed there.  If the old stuff 
worked, that tends to imply a problem with the new stuff...

	Jeff


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