Hello.
On 9/8/2014 10:10 PM, Leonid Yegoshin wrote:
Patch commit b6d92b4a6bdb880b39789c677b952c53a437028d
Just commit.
MIPS: Add option to disable software I/O coherency.
It's enough to just cite the summary in parens after SHA1 ID.
Some MIPS controllers have hardware I/O coherency. This patch
detects those and turns off software coherency. A new kernel
command line option also allows the user to manually turn
software coherency on or off.
in fact enforces L2 cache flushes even on systems with IOCU.
The default value of coherentio is 0 and is not changed even with IOCU.
It is a serious performance problem because it destroys all IOCU performance
advantages.
It is fixed by setting coherentio to tri-state with default value as (-1) and
setup a final value during platform coherency setup.
Signed-off-by: Leonid Yegoshin <leonid.yegos...@imgtec.com>
---
V2: Missed signature added
---
arch/mips/include/asm/mach-generic/dma-coherence.h | 7 ++++++-
arch/mips/mm/c-r4k.c | 2 +-
arch/mips/mm/dma-default.c | 2 +-
arch/mips/mti-malta/malta-setup.c | 8 ++++++--
arch/mips/pci/pci-alchemy.c | 2 +-
5 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/arch/mips/include/asm/mach-generic/dma-coherence.h
b/arch/mips/include/asm/mach-generic/dma-coherence.h
index 7629c35..b4563df 100644
--- a/arch/mips/include/asm/mach-generic/dma-coherence.h
+++ b/arch/mips/include/asm/mach-generic/dma-coherence.h
@@ -49,7 +49,12 @@ static inline int plat_dma_supported(struct device *dev, u64
mask)
static inline int plat_device_is_coherent(struct device *dev)
{
- return coherentio;
+#ifdef CONFIG_DMA_COHERENT
+ return 1;
+#else
+ return (coherentio > 0);
*return* never needs parens around the value.
+#endif
+
}
#ifdef CONFIG_SWIOTLB
diff --git a/arch/mips/mti-malta/malta-setup.c
b/arch/mips/mti-malta/malta-setup.c
index db7c9e5..48039fd 100644
--- a/arch/mips/mti-malta/malta-setup.c
+++ b/arch/mips/mti-malta/malta-setup.c
@@ -147,13 +147,17 @@ static void __init plat_setup_iocoherency(void)
if (plat_enable_iocoherency()) {
if (coherentio == 0)
pr_info("Hardware DMA cache coherency disabled\n");
- else
+ else {
+ coherentio = 1;
You now need the parens around another arm of the *if* statement too. Such
is the kernel style. :-)
pr_info("Hardware DMA cache coherency enabled\n");
+ }
} else {
if (coherentio == 1)
pr_info("Hardware DMA cache coherency unsupported, but
enabled from command line!\n");
- else
+ else {
+ coherentio = 0;
Likewise.
pr_info("Software DMA cache coherency enabled\n");
+ }
}
#else
if (!plat_enable_iocoherency())
WBR, Sergei
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