Russell King 2be23c475a ARM: Ensure PTE modifications via dma_alloc_coherent are visible ... Dave Hylands reports: | We've observed a problem with dma_alloc_writecombine when the system | is under heavy load (heavy bus traffic). We've managed to reduce the | problem to the following snippet, which is run from a kthread in a | continuous loop: | | void *virtAddr; | dma_addr_t physAddr; | unsigned int numBytes = 256; | | for (;;) { | virtAddr = dma_alloc_writecombine(NULL, | numBytes, &physAddr, GFP_KERNEL); | if (virtAddr == NULL) { | printk(KERN_ERR "Running out of memory\n"); | break; | } | | /* access DMA memory allocated */ | tmp = virtAddr; | *tmp = 0x77; | | /* free DMA memory */ | dma_free_writecombine(NULL, | numBytes, virtAddr, physAddr); | | ...sleep here... | } | | By itself, the code will run forever with no issues. However, as we | increase our bus traffic (typically using DMA) then the *tmp = 0x77 | line will eventually cause a page fault. If we add a small delay (a | few microseconds) before the *tmp = 0x77, then we don't see a page | fault, even under heavy load. A dsb() is required after modifying the PTE entries to ensure that they will always be visible. Add this dsb(). Reported-by: Dave Hylands <dhylands@gmail.com> Tested-by: Dave Hylands <dhylands@gmail.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>		2010-09-08 16:27:56 +01:00
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abort-ev4.S
abort-ev4t.S
abort-ev5t.S
abort-ev5tj.S
abort-ev6.S
abort-ev7.S
abort-lv4t.S
abort-macro.S
abort-nommu.S
alignment.c
cache-fa.S
cache-feroceon-l2.c
cache-l2x0.c
cache-tauros2.c
cache-v3.S
cache-v4.S
cache-v4wb.S
cache-v4wt.S
cache-v6.S
cache-v7.S
cache-xsc3l2.c
context.c
copypage-fa.c
copypage-feroceon.c
copypage-v3.c
copypage-v4mc.c
copypage-v4wb.c
copypage-v4wt.c
copypage-v6.c
copypage-xsc3.c
copypage-xscale.c
dma-mapping.c	ARM: Ensure PTE modifications via dma_alloc_coherent are visible	2010-09-08 16:27:56 +01:00
extable.c
fault-armv.c
fault.c
fault.h
flush.c
highmem.c
init.c
iomap.c
ioremap.c
Kconfig
Makefile
mm.h
mmap.c
mmu.c
nommu.c
pabort-legacy.S
pabort-v6.S
pabort-v7.S
pgd.c
proc-arm6_7.S
proc-arm7tdmi.S
proc-arm9tdmi.S
proc-arm720.S
proc-arm740.S
proc-arm920.S
proc-arm922.S
proc-arm925.S
proc-arm926.S
proc-arm940.S
proc-arm946.S
proc-arm1020.S
proc-arm1020e.S
proc-arm1022.S
proc-arm1026.S
proc-fa526.S
proc-feroceon.S
proc-macros.S
proc-mohawk.S
proc-sa110.S
proc-sa1100.S
proc-syms.c
proc-v6.S
proc-v7.S
proc-xsc3.S
proc-xscale.S
tlb-fa.S
tlb-v3.S
tlb-v4.S
tlb-v4wb.S
tlb-v4wbi.S
tlb-v6.S
tlb-v7.S
vmregion.c
vmregion.h