[ltp] T43: No DMA for /dev/hdc (Ultrabay Slim HDD)

[Henrique de Moraes Holschuh]

On Fri, 08 Dec 2006, Henrique de Moraes Holschuh wrote:
> You need libata.  Linux will be talking to an ICH that talks to the Ultrabay
> over a *SATA* channel, no matter what is in the bay.

Drat. I was wrong about this part:

This is from a T43, kernel 2.6.18:

ata_piix 0000:00:1f.2: version 2.00
ata_piix 0000:00:1f.2: MAP [ P0 P2 IDE IDE ]
ata1: SATA max UDMA/133 cmd 0x1F0 ctl 0x3F6 bmdma 0x18C0 irq 14
ata2: PATA max UDMA/100 cmd 0x170 ctl 0x376 bmdma 0x18C8 irq 15

That, AFAIK, means the ultrabay channel is a PATA one, and that the ICH
device is in combined mode.  I wonder what was done in the *60?  Drop PATA
support, or route a PATA and a SATA channel there?

This explains why ide-generic can actually sort-of-work, it does so over the
standard IDE BARs but that does means generic support (so, no DMA).

I wonder what is the output of a T60 in combined and AHCI modes...

> DMA in that *hardware* config requires libata.  ATAPI with DMA support needs
> libata with ATAPI support enabled.  Bay hotplug with DMA support needs
> 2.6.18 or 2.6.19 libata with ATAPI support enabled.

This is still true.  You need libata to drive a ICH in combined mode with
DMA support.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh