[PATCH] arm64: Define HAVE_ARCH_PIO_SIZE and related symbols.
ddaney at caviumnetworks.com
Tue Jul 14 09:58:20 PDT 2015
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 at 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 (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.
More information about the linux-arm-kernel