Re: [PATCH 2/3] libata: extend ata_acpi_cbl_80wire() and fix cable detection in pata_via and pata_amd

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

On Friday 02 November 2007, Alan Cox wrote:
> > Using the initial GTM value is the right thing to do because both are
> > trying to check firmware setting and by the time ->cable_detect runs
> > the controller is already forced into PIO0 by reset.
> 
> As we only look at the DMA bits that doesn't matter but I agree it would

It does matter,

http://lkml.org/lkml/2007/10/12/537

"
>       libata: correct handling of SRST reset sequences

This potentially adds a regression for nVidia boxes (but ACPI cable
detection should compensate for it):

pata_amd's ->cable_detect checks UDMA timings to get the cable type
(cable detection is done before the SRST) but pata_amd's ->set_piomode
messes with UDMA timings.  It seems that both methods need fixing.
"

[ Now we see that since ACPI can just dump the current settings
  ACPI cable detection won't help a tiny bit. ]

AFAICS pata_via.c has the same problem w.r.t. ->set_piomode

> be cleaner if we were more careful. Also our mode setting outside
> pata_acpi doesn't touch the ACPI settings so its ok for that reason too.

Thanks,
Bart