Messages in this thread | | | Date | Fri, 12 May 2006 23:42:34 -0400 | From | Jeff Garzik <> | Subject | Re: ata_piix failure on ich6m |
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Tejun Heo wrote: > Matthew Garrett wrote: >> Hi, >> >> We've got an ich6m system (a Toshiba Portege S100). ata_piix attempts >> to drive the chipset, but fails - however, it doesn't bail out. As a >> result it remains bound to the device and ahci isn't loaded. >> >> I've attached the lspci output for the chipset. A few things to note are: >> >> 1) The AHCI BAR is set >> 2) The SCC register identifies it as an AHCI controller >> 3) Bits 2 and 0 of the PCS are set, which the spec claims indicates >> that the port is to be controlled as an ahci device. >> >> So, my question is effectively: why does ata_piix attempt to disable >> ahci rather than simply letting the ahci driver bind? Points (1) and >> (2) seem to be checked by the code, but I'm guessing that in the case >> of (3) it should just return ENODEV and let ahci be run instead. If >> so, should I code up a patch? >> > > I'm not very sure but it might be historical. ahci got implemented > after ata_piix and in the meantime ata_piix must have handled all it > could. Can you verify whether modifying the code to return -ENODEV work > for your machine? If so, that could be the correct solution but I'm a > bit worried because it could change probing order or fail to enable > devices it used to. Maybe we need a hack to return -ENODEV iff ahci is > there to handle the device.
It's definitely historical. I'm pretty frazzled now so I don't remember. It may be that on ICH6, AHCI mode does not cause the PCI IDs to change, so driver load order winds up dictating what gets used.
Jeff
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