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 Saturday 03 November 2007, Bartlomiej Zolnierkiewicz wrote:
> 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

s/after/before/ of course

> 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