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SubjectRe: [PATCH V2] MIPS: bugfix of coherentio variable default setup
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.Yegoshin@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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