The patch below does not apply to the 3.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From dcad68876c21bac709b01eda24e39d4410dc36a8 Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> Date: Wed, 28 Jan 2015 12:55:45 +0100 Subject: [PATCH] ARM: mvebu: don't set the PL310 in I/O coherency mode when I/O coherency is disabled Since commit f2c3c67f00 (merge commit that adds commit "ARM: mvebu: completely disable hardware I/O coherency"), we disable I/O coherency on Armada EBU platforms. However, we continue to initialize the coherency fabric, because this coherency fabric is needed on Armada XP for inter-CPU coherency. Unfortunately, due to this, we also continued to execute the coherency fabric initialization code for Armada 375/38x, which switched the PL310 into I/O coherent mode. This has the effect of disabling the outer cache sync operation: this is needed when I/O coherency is enabled to work around a PCIe/L2 deadlock. But obviously, when I/O coherency is disabled, having the outer cache sync operation is crucial. Therefore, this commit fixes the armada_375_380_coherency_init() so that the PL310 is switched to I/O coherent mode only if I/O coherency is enabled. Without this fix, all devices using DMA are broken on Armada 375/38x. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> Acked-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx> Tested-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Lunn <andrew@xxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # v3.8+ diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c index caa21e9b8cd9..ccef8806bb58 100644 --- a/arch/arm/mach-mvebu/coherency.c +++ b/arch/arm/mach-mvebu/coherency.c @@ -190,6 +190,13 @@ static void __init armada_375_380_coherency_init(struct device_node *np) arch_ioremap_caller = armada_pcie_wa_ioremap_caller; /* + * We should switch the PL310 to I/O coherency mode only if + * I/O coherency is actually enabled. + */ + if (!coherency_available()) + return; + + /* * Add the PL310 property "arm,io-coherent". This makes sure the * outer sync operation is not used, which allows to * workaround the system erratum that causes deadlocks when -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html