Re: [PATCH v2 1/1] MIPS: Malta: Use pcibios_align_resource() to block io range

[Ilpo Järvinen]

On Tue, 21 Oct 2025, Maciej W. Rozycki wrote:

> On Mon, 20 Oct 2025, Bjorn Helgaas wrote:
> 
> > > Since ae81aad5c2e1 ("MIPS: PCI: Use pci_enable_resources()") came
> > > through the PCI tree, I'd be happy to merge this as well, given your
> > > ack, Thomas.  It would be ideal to have a tested-by from Guenter.
> > > 
> > > I provisionally put it on pci/for-linus to facilitate testing.  If it
> > > doesn't solve the problem or you'd rather take it, Thomas, I'll be
> > > glad to drop it.
> > 
> > Added:
> > 
> >   Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> >   Tested-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
> >   Acked-by: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
> > 
> > and dropped the Fixes: aa0980b80908 ("Fixes for system controllers for
> > Atlas/Malta core cards.")
> > 
> > If the missing resource reservations (dma1, tiger, dma page reg)
> > mentioned by Maciej are an issue or can be fixed up, let me know and
> > we can amend this.
> 
>  NB this comes from `plat_mem_setup' in arch/mips/mti-malta/malta-setup.c 
> iterating over `standard_io_resources'.  ISTR now this being my original 
> reason to come up with the approach taken with commit aa0980b80908 rather 
> than using PCIBIOS_MIN_IO.  Since the ranges are now owned by the PCI host 
> bridge, calls to `request_resource' referring `ioport_resource' fail.

So this platform would actually need multiple root bus IO resources to 
cover PIIX4 range without capturing non-PCI ranges?

>  I'm not sure offhand how to get a hold on the right handle under the new 
> arrangement in this platform code, but clearly it must be doable as x86 
> gets it right (and conversely Alpha gets it totally wrong).
> 
>  Also I think we should reserve the PCI port I/O window in the MMIO space 
> as well; something that I pondered back those 20 years ago already.  For 
> the system I've used here that'd show up as:
> 
> 10000000-1affffff : MSC PCI MEM
>   10000000-100fffff : 0000:00:0b.0
>   [...]
>   10142080-1014209f : 0000:00:0b.0
> 1b000000-1bffffff : MSC PCI I/O
> 1e000000-1e3fffff : 1e000000.flash flash@1e000000
> 
> Most non-x86 PCI host bridges have one, but I haven't come across a Linux
> platform that would report it.
> 
>   Maciej
> 

-- 
 i.