On Fri, May 16, 2014 at 09:07:27AM +0200, Thomas Petazzoni wrote: > Dear Jason Cooper, > > On Fri, 16 May 2014 02:08:51 -0400, Jason Cooper wrote: > > On Thu, May 15, 2014 at 04:59:34PM +0200, Thomas Petazzoni wrote: > > > The Marvell Armada 375 and Armada 38x SOCs, which use the Cortex-A9 > > > CPU core, the PL310 cache and the Marvell PCIe hardware block are > > > affected a L2/PCIe deadlock caused by a system erratum when hardware > > > I/O coherency is used. > > > > > > This deadlock can be avoided by mapping the PCIe memory areas as > > > strongly-ordered (note: MT_UNCACHED is strongly-ordered), and by > > > removing the outer cache sync done in software. This is implemented in > > > this patch by: > > > > > > * Registering a custom arch_ioremap_caller function that allows to > > > make sure PCI memory regions are mapped MT_UNCACHED. > > > > > > * Adding at runtime the 'arm,io-coherent' property to the PL310 cache > > > controller. This cannot be done permanently in the DT, because the > > > hardware I/O coherency can only be enabled when CONFIG_SMP is > > > enabled, in the current kernel situation. > > > > > > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> > > > --- > > > arch/arm/mach-mvebu/coherency.c | 39 +++++++++++++++++++++++++++++++++++++++ > > > 1 file changed, 39 insertions(+) > > > > Applied to mvebu/soc. > > Hum, well, I believe it's OK, but notice that I will very likely have > to do a followup patch, because the solution of making all PCI I/O > mappings use the MT_UNCACHED memory type, suggested by Arnd, has not > been accepted by Will Deacon. So very likely I will have to change > again the mach-mvebu/coherency.c code to call a function that makes PCI > I/O mappings MT_UNCACHED specifically for the mach-mvebu platform. But > that can indeed be a followup patch. Ahh, my mistake. It was late. I saw the arm,io-coherent was settled and mistakenly thought the other proposed changes wouldn't affect this patch. I could easily drop it if you like. It's currently the tip of mvebu/soc and I haven't done a signed tag for it yet. thx, Jason. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
