Re: [PATCH] libata: fix combined mode (was Re: Happy New Year (and v2.6.20-rc3 released))

Jeff Garzik
2007-01-02T23:43:56Z

Alan wrote:
>> 2.6.0 - 2.6.19: libata guarantees that all PCI BARs are reserved to the
>> libata driver.
>
> Please read the code Jeff. The old IDE quirk code in the PCI layer blanked
> BAR 0 to BAR 3 of a compatibility mode controller

(a) I'm well of aware of this, and (b) that changes nothing.

I said "PCI BARs" for a reason. libata was written according to the
following model:

1) Programmatically reserve /all/ resources associated with
our PCI device
2) Manually reserve resources associated with our PCI device,
but are not listed in struct pci_dev.

You have changed this to:

1) Manually reserve /some/ resources associated with PCI device
2) Manually reserve resources associated with our PCI device,
but are not listed in struct pci_dev.

But then 2.6.21 goes back to:

1) Programmatically reserve /all/ resources associated with
our PCI device
2) Manually reserve resources associated with our PCI device,
but are not listed in struct pci_dev.

Maybe I can say it more clearly by telling you how to fix the regression
you have introduced: Loop through all BAR resources in struct pci_dev,
and reserve them if they are not already reserved by libata earlier in
the code. There. Regression fixed.

(but then we rewrite this code again in 2.6.21)

> You then request_region 0x1f0 and 0x170 (BAR 0 and BAR 2) directly. You
> never request the legacy BAR 1 and BAR 3 because they were erased by the
> PCI quirk code and thus never claim the other port. Thats been a bug since
> day one but it never seemed worth fixing in the short term.

Yes -- that's a bug, one that existed prior to the "it doesn't boot"
combined mode regression everybody complained about. I'm talking about
a new regression just introduced via
dc3c3377f03634d351fafdfe35b237b283586c04, not a old bug that existed
prior to the regression introduced in
368c73d4f689dae0807d0a2aa74c61fd2b9b075f.

Jeff