Re: [PATCHv5 4/4] ARM: mvebu: use pci_ioremap_set_mem_type() to map PCI I/O as strongly ordered

[Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org>]

On Mon, May 19, 2014 at 09:13:54AM +0100, Thomas Petazzoni wrote:
> Part of the workaround for the PCIe/SMP/PL310 deadlock on Armada
> 375/38x is to map PCI mappings strongly ordered. Mapping PCI memory
> regions as strongly ordered was already done thanks to the
> arch_ioremap_caller mechanism. This patch does the same for the PCI
> I/O regions by using the new pci_ioremap_set_mem_type() function.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> ---
>  arch/arm/mach-mvebu/coherency.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
> index f6be9c6..0215614 100644
> --- a/arch/arm/mach-mvebu/coherency.c
> +++ b/arch/arm/mach-mvebu/coherency.c
> @@ -335,6 +335,7 @@ static void __init armada_375_380_coherency_init(struct device_node *np)
>  
>  	coherency_cpu_base = of_iomap(np, 0);
>  	arch_ioremap_caller = armada_pcie_wa_ioremap_caller;
> +	pci_ioremap_set_mem_type(MT_UNCACHED);

The patch is fine but for this to work in the UP case we need to fix
MT_UNCACHED definition for sections. It seems to create SO memory but
not necessarily writable (unless I miss something). Anyway, untested,
something like this:

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index b68c6b22e1c8..db1bf8cb3a3e 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -267,7 +267,7 @@ static struct mem_type mem_types[] = {
 	[MT_UNCACHED] = {
 		.prot_pte	= PROT_PTE_DEVICE,
 		.prot_l1	= PMD_TYPE_TABLE,
-		.prot_sect	= PMD_TYPE_SECT | PMD_SECT_XN,
+		.prot_sect	= PROT_SECT_DEVICE,
 		.domain		= DOMAIN_IO,
 	},
 	[MT_CACHECLEAN] = {
@@ -461,6 +461,7 @@ static void __init build_mem_type_table(void)
 			mem_types[MT_DEVICE_NONSHARED].prot_sect |= PMD_SECT_XN;
 			mem_types[MT_DEVICE_CACHED].prot_sect |= PMD_SECT_XN;
 			mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_XN;
+			mem_types[MT_UNCACHED].prot_sect |= PMD_SECT_XN;
 
 			/* Also setup NX memory mapping */
 			mem_types[MT_MEMORY_RW].prot_sect |= PMD_SECT_XN;

-- 
Catalin
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