Messages in this thread | | | Date | Tue, 14 Jul 2015 09:58:20 -0700 | From | David Daney <> | Subject | Re: [PATCH] arm64: Define HAVE_ARCH_PIO_SIZE and related symbols. |
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On 07/14/2015 09:29 AM, Will Deacon wrote: > On Tue, Jul 14, 2015 at 05:12:57PM +0100, David Daney wrote: >> On 07/14/2015 04:00 AM, Will Deacon wrote: >>> On Mon, Jul 13, 2015 at 10:31:36PM +0100, David Daney wrote: >>>> From: David Daney <david.daney@cavium.com> >>>> >>>> Needed to make pci_iomap() work. >>> >>> Care to elaborate? >>> >> >> I should have explained what I am doing here a little better. > > Yeah, thanks. > >> Systems based on the Cavium ThunderX processor may have up to 8 >> independent PCIe root complexes. The I/O space on each bus occupies an >> independent physical address window. > > Hmm, so do you have 64k of I/O space per-bus? That gives 8x256x64k = 128M > IIUC, so not sure what your 32MB is for.
I don't understand where your 256 came from there.
Actually, my current implementation has 1M per bus(which is overkill). For 8 buses I need 8M, which fits within the PCI_IO_SIZE...
> >> So, in order to be able to map all of these (semi) contiguously, we need >> a lot more virtual address space than is supplied by the default values >> for all these constants. >> >> The option I chose here was to unconditionally expand the I/O ranges for >> all arm64 systems. If you think this breaks existing systems/drivers, I >> will have to look for other options. > > Hmm, but pci_iomap winds up calling __pci_ioport_map, which expands to > ioport_map which just does: > > return PCI_IOBASE + (port & IO_SPACE_LIMIT); > > so I'm struggling to see what your patch achieves.
Here is ioport_map (from lib/iomap.c):
void __iomem *ioport_map(unsigned long port, unsigned int nr) { if (port > PIO_MASK) return NULL; return (void __iomem *) (unsigned long) (port + PIO_OFFSET); }
With the default value of PIO_MASK (64K), I cannot map any I/O ports on my PCIe RC 1..7
The values I supplied in my patch may be sub-optimal, but I think something is needed. I will look into this in a little more detail today.
Thanks, David Daney
> > Will >
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