Re: [PATCH 1/2] pata_legacy: export functionality to ide

[Sergei Shtylyov]

Borislav Petkov wrote:

> > > > > From: Borislav Petkov <petkovbb@xxxxxxxxx>
> > > > > Date: Sun, 3 Aug 2008 18:46:35 +0200
> > > > > Subject: [PATCH] ide-generic: handle probing of legacy io-ports v4

> > > > > Avoid probing the io-ports in case an IDE PCI controller is present and it uses
> > > > > the legacy iobases. If we still want to enforce the probing, we do

> > > > > ide_generic.probe_mask=0x3f

> > > > > on the kernel command line. The iobase checking code is adapted from
> > > > > drivers/ata/pata_legacy.c after converting hex pci ids into their
> > > > > corresponding
> > > > > macros in <linux/pci_ids.h>.

> > > > > CC: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
> > > > > Signed-off-by: Borislav Petkov <petkovbb@xxxxxxxxx>

> > > > Acked-by: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>

> > > > > diff --git a/drivers/ide/ide-generic.c b/drivers/ide/ide-generic.c
> > > > > index 8fe8b5b..efce159 100644
> > > > > --- a/drivers/ide/ide-generic.c
> > > > > +++ b/drivers/ide/ide-generic.c

> > > > [...]

> > > > > @@ -100,19 +101,69 @@ static const u16 legacy_bases[] = { 0x1f0, 0x170,
> > > > > 0x1e8, 0x168, 0x1e0, 0x160 };
> > > > > static const int legacy_irqs[]  = { 14, 15, 11, 10, 8, 12 };
> > > > > #endif
> > > > > +static void ide_generic_check_pci_legacy_iobases(int *primary, int
> > > > > *secondary)
> > > > > +{
> > > > > +       struct pci_dev *p = NULL;
> > > > > +       u16 val;
> > > > > +
> > > > > +       for_each_pci_dev(p) {
> > > > > +               int r;
> > > > > +
> > > > > +               for (r = 0; r < 6; r++) {
> > > > > +                       if (pci_resource_start(p, r) == 0x1f0)
> > > > > +                               *primary = 1;
> > > > > +                       if (pci_resource_start(p, r) == 0x170)
> > > > > +                               *secondary = 1;
> > > > > +               }

> > > > Would have been probably enough to test only BAR0/2, don't you think?

> > > I assume you're referring to the legacy ioports fixup in
> > > drivers/pci/probe.c:pci_setup_device().

> >   And to the fact that the value 0x1f0 should only be ever seen in BAR0 
> > and 0x170 in BAR2 even if they would have been read off the chips (some 
> > chips have these values reading back even in legacy mode, and even could 
> > malfunction if other values are written there), not fixed up there, and 
> > certainly not in BAR1 or BAR3, so it's quite pointless to look in these 
> > BARs too.

> So the comment in there saying that in some cases BAR0-3 could contain junk is a
> bogus?

   Don't know. The PCI IDE spec. said that those should be 0 in compatibility 
mode but I know that some controllers require the standard values of 0x1[f7]0 
to be in BAR0/2 in compatibility mode. If my memory serves, NatSemi PC8741x 
were ones of those...

> In other words, can we assume that one will always read 0x1f0 from BAR0
> and 0x170 from BAR2 in compatibility mode.

   Certainly not. We can only rely on the workaround putting 0x1[f7]0 in the 
resources 0/2.

> If so, the check is even simpler:

> 	if (pci_resource_start(p, 0) == 0x1f0)
> 		*primary = 1;
> 	if (pci_resource_start(p, 2) == 0x170)
> 		*secondary = 1;

   Yes, I think that should be enough...

WBR, Sergei
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