IDE cable detection on Apple PowerBook

[Benjamin Herrenschmidt]

On Wed, 2009-03-18 at 22:47 +0900, TOMARI Hisanobu wrote:
> I thought the short-40pin assumption would cause no problem
> considering all models beginning with "PowerBook5" are laptops.
> Do you mean an option to toggle this hack on/off should be present 
> in Kconfig?

Actually, it makes -some- amount of sense to do it by testing
specifically for the prefix "PowerBook" and "iBook" without a specific
number I suppose.

Ben.

> Thanks,
> TOMARI Hisanobu
> 
> On Wed, 18 Mar 2009 18:58:17 +1100
> Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:
> 
> > On Wed, 2009-03-18 at 14:06 +0900, TOMARI Hisanobu wrote:
> > > Hello,
> > > 
> > > I'm using an OCZ PATA SSD on Apple PowerBook5,4 computer.
> > > The IDE drive fails to recognize 80-conductor cable that
> > > connects the drive to motherboard to fall back to UDMA33.
> > > 
> > > This patch fixes this behavior by assuming that the cable is
> > > short-40pin when the model string matches "PowerBook5" and 
> > > the motherboard detects 80c cable.
> > > 
> > > This patch is against drivers/ide/pmac.c in linux 2.6.28.8.
> > 
> > The patch is too much of an ad-hoc hack... _maybe_ an option is to make
> > the core fallback to 40 "short" when 80 pin detection fails on
> > powerbooks instead ?
> > 
> > Ben.
> > 
> > > (before applying the patch) hdparm -i /dev/hda
> > > /dev/hda:
> > >  Timing buffered disk reads:   90 MB in  3.03 seconds =  29.73 MB/sec
> > > (dmesg 2.6.26)
> > > ide0: Found Apple UniNorth ATA-6 controller, bus ID 3, irq 39
> > > Probing IDE interface ide0...
> > > hda: CORE_PATA, ATA DISK drive
> > > hda: host max PIO4 wanted PIO255(auto-tune) selected PIO4
> > > hda: drive side 80-wire cable detection failed, limiting max speed to UDMA33
> > > hda: UDMA/33 mode selected
> > > 
> > > (after applying the patch) hdparm -i /dev/hda
> > > /dev/hda:
> > >  Timing buffered disk reads:  240 MB in  3.02 seconds =  79.42 MB/sec
> > > (dmesg 2.6.28.8)
> > > ide-pmac: Found Apple UniNorth ATA-6 controller (PCI), bus ID 3, irq 39
> > > Probing IDE interface ide0...
> > > hda: CORE_PATA, ATA DISK drive
> > > hda: host max PIO4 wanted PIO255(auto-tune) selected PIO4
> > > hda: UDMA/100 mode selected
> > > ide0 at 0xf102a000-0xf102a070,0xf102a160 on irq 39
> > > 
> > > 
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> >