From 6a02734d420fca778554878d03017017537d92e1 Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Thu, 16 Jun 2016 15:42:26 +0200 Subject: ARM: mvebu: map PCI I/O regions strongly ordered In order for HW I/O coherency to work on Cortex-A9 based Marvell SoCs, all MMIO registers must be mapped strongly ordered. In commit 1c8c3cf0b5239 ("ARM: 8060/1: mm: allow sub-architectures to override PCI I/O memory type") we implemented a new function, pci_ioremap_set_mem_type(), that allow sub-architecture code to override the memory type used to map PCI I/O regions. In the discussion around this patch series [1], Arnd Bergmann made the comment that maybe all PCI I/O regions should be mapped strongly-ordered, which would have made our proposal to add pci_ioremap_set_mem_type() irrelevant. So, we submitted a patch [2] that did what Arnd suggested. However, Russell in the end merged our initial proposal to add pci_ioremap_set_mem_type(), but it was never used anywhere. Further discussion with Arnd and other folks on IRC lead to the conclusion that in fact using strongly-ordered for all platforms was maybe not desirable, and therefore, using pci_ioremap_set_mem_type() was the most appropriate solution. As a consequence, this commit finally adds the pci_ioremap_set_mem_type() call in the mach-mvebu platform code, which was originally part of our initial patch series [3] and is necessary for the whole mechanism to work. [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-May/256565.html [2] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-May/256755.html [3] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-May/256563.html Signed-off-by: Thomas Petazzoni Signed-off-by: Gregory CLEMENT --- arch/arm/mach-mvebu/coherency.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm/mach-mvebu') diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c index 474abff7e855..e80f0dde2189 100644 --- a/arch/arm/mach-mvebu/coherency.c +++ b/arch/arm/mach-mvebu/coherency.c @@ -181,6 +181,7 @@ static void __init armada_375_380_coherency_init(struct device_node *np) coherency_cpu_base = of_iomap(np, 0); arch_ioremap_caller = armada_wa_ioremap_caller; + pci_ioremap_set_mem_type(MT_UNCACHED); /* * We should switch the PL310 to I/O coherency mode only if -- cgit v1.2.3