On Wed, Jan 30, 2013 at 03:08:56PM +0000, Russell King - ARM Linux wrote:

quoted

On Wed, Jan 30, 2013 at 01:03:44PM +0100, Thierry Reding wrote:

quoted

On Wed, Jan 30, 2013 at 11:32:46AM +0000, Russell King - ARM Linux wrote:

quoted

On Mon, Jan 28, 2013 at 07:56:28PM +0100, Thomas Petazzoni wrote:

quoted

+static resource_size_t mvebu_pcie_align_resource(struct pci_dev *dev,
+						 const struct resource *res,
+						 resource_size_t start,
+						 resource_size_t size,
+						 resource_size_t align)
+{
+	if (!(res->flags & IORESOURCE_IO))
+		return start;
+
+	/*
+	 * The I/O regions must be 64K aligned, because the
+	 * granularity of PCIe I/O address decoding windows is 64 K
+	 */
+	return round_up(start, SZ_64K);
+}

You do realise that this will result in all PCI I/O BARs being rounded
up to 64K.

I've just been digging through the PCI code and have come across a
function - pcibios_window_alignment() - which the PCI code allows to be
overriden which allows you to increase the alignment requirement of
bridge windows.  It takes the PCI bus and window type as arguments.

I'd suggest using that, and checking whether the bus which is passed
corresponds with a bus which gives you problems, so that you don't
impose the 64K requirement on downstream bridges.

That approach isn't going to work very well with multi-platform, though,
since the function can only be overridden on a per-architecture basis.

The same can be said of all the various other functions which the PCI
stuff expects the arch to provide, yet we seem to cope just fine...

And this (untested) is how it's done:

 arch/arm/include/asm/mach/pci.h |    1 +
 arch/arm/kernel/bios32.c        |    8 ++++++++
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/pci.h
index db9fedb..bba0cf3 100644
--- a/arch/arm/include/asm/mach/pci.h
+++ b/arch/arm/include/asm/mach/pci.h

@@ -29,6 +29,7 @@ struct hw_pci {
 	void		(*postinit)(void);
 	u8		(*swizzle)(struct pci_dev *dev, u8 *pin);
 	int		(*map_irq)(const struct pci_dev *dev, u8 slot, u8 pin);
+	resource_size_t	(*window_align)(struct pci_bus *, unsigned long);
 };
 
 /*

diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index 379cf32..32c3bd9 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c

@@ -581,6 +581,14 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
 	return start;
 }
 
+resource_size_t pcibios_window_alignment(struct pci_bus *bus,
+					 unsigned long type)
+{
+	struct pci_sys_data *sys = bus->sysdata;
+
+	return sys->window_alignment ? sys->window_alignment(bus, type) : 1;
+}
+
 /**
  * pcibios_enable_device - Enable I/O and memory.
  * @dev: PCI device to be enabled