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authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>2016-06-16 16:42:26 +0300
committerGregory CLEMENT <gregory.clement@free-electrons.com>2016-06-16 18:00:40 +0300
commit6a02734d420fca778554878d03017017537d92e1 (patch)
treee59962caeafb8f45eac7ae3fae94a7e4423f74e0 /Documentation/PCI
parentc5379ba8fccd99d5f99632c789f0393d84a57805 (diff)
downloadlinux-6a02734d420fca778554878d03017017537d92e1.tar.xz
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 <thomas.petazzoni@free-electrons.com> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
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