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authorEugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>2018-07-30 19:26:35 +0300
committerVineet Gupta <vgupta@synopsys.com>2018-09-04 23:21:37 +0300
commit2b720e99a1297417b979bf4810a0f01d27133c48 (patch)
tree3becef1f38b77766b6427242eadce453ee7b5226 /arch
parent2820a708d5a321342bef34e459fdc8679c30e20f (diff)
downloadlinux-2b720e99a1297417b979bf4810a0f01d27133c48.tar.xz
ARC: IOC: panic if both IOC and ZONE_HIGHMEM enabled
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arc/mm/cache.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
index 2d389cab46ba..f2701c13a66b 100644
--- a/arch/arc/mm/cache.c
+++ b/arch/arc/mm/cache.c
@@ -1144,6 +1144,19 @@ noinline void __init arc_ioc_setup(void)
{
unsigned int ioc_base, mem_sz;
+ /*
+ * As for today we don't support both IOC and ZONE_HIGHMEM enabled
+ * simultaneously. This happens because as of today IOC aperture covers
+ * only ZONE_NORMAL (low mem) and any dma transactions outside this
+ * region won't be HW coherent.
+ * If we want to use both IOC and ZONE_HIGHMEM we can use
+ * bounce_buffer to handle dma transactions to HIGHMEM.
+ * Also it is possible to modify dma_direct cache ops or increase IOC
+ * aperture size if we are planning to use HIGHMEM without PAE.
+ */
+ if (IS_ENABLED(CONFIG_HIGHMEM))
+ panic("IOC and HIGHMEM can't be used simultaneously");
+
/* Flush + invalidate + disable L1 dcache */
__dc_disable();