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Date: Wed, 6 Mar 2013 10:50:09 +0100
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Lior Amsalem <alior@marvell.com>, Andrew Lunn <andrew@lunn.ch>,
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	Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Subject: Re: [PATCH 24/32] pci: PCIe driver for Marvell Armada 370/XP
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Dear Arnd Bergmann,

On Wed, 13 Feb 2013 10:37:02 +0000, Arnd Bergmann wrote:

> Yes, of course. And the ranges property tells you how to turn the
> first address space into the second address space. So the above
> property defines that the PCI bus I/O space range from 0 to 0x10000
> gets converted into the host MMIO range 0xc0000000 to 0xc0010000 on
> the host, and the PCI bus memory space range from 0 to 0x08000000
> gets converted to the host MMIO range 0xc1000000 to 0xc9000000.
> 
> The output of your of_pci_process_ranges() function is the host MMIO
> range, not the range in the bus address space, so it has to be
> IORESOURCE_MEM.

I am sorry, but I don't get how this can work. My code currently relies
on the DT encoding one I/O resource and one MEM resource to find which
is one to use.

Right now, in the ranges property of my DT, I have:

          0x81000000 0 0          0xc0000000 0 0x00010000   /* downstream I/O */
          0x82000000 0 0          0xc1000000 0 0x08000000>; /* non-prefetchable memory */

And the code parsing this does:

        /* Get the I/O and memory ranges from DT */
        while ((range = of_pci_process_ranges(np, &res, range)) != NULL) {
                if (resource_type(&res) == IORESOURCE_IO) {
                        memcpy(&pcie->io, &res, sizeof(res));
                        memcpy(&pcie->realio, &res, sizeof(res));
                        pcie->io.name = "I/O";
                        pcie->realio.start &= 0xFFFFF;
                        pcie->realio.end   &= 0xFFFFF;
                }
                if (resource_type(&res) == IORESOURCE_MEM) {
                        memcpy(&pcie->mem, &res, sizeof(res));
                        pcie->mem.name = "MEM";
                }
        }

As you can see, it relies on one of the two ranges being for I/O
(address starts with 0x81), and another range being for MEM (address
starts with 0x82).

If I make both ranges start with 0x82, how can my code differentiate
between the range used for I/O and the range used for MEM?

Thanks,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com