From: Paul Burton <paul.burton@mips.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>, Guan Xuetao <gxt@pku.edu.cn>,
Shawn Anastasio <shawn@anastas.io>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
James Hogan <jhogan@kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-m68k@lists.linux-m68k.org"
<linux-m68k@lists.linux-m68k.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 6/6] MIPS: document mixing "slightly different CCAs"
Date: Tue, 27 Aug 2019 10:03:16 +0000 [thread overview]
Message-ID: <20190827100310.p2o5y3aklcoti74z@pburton-laptop> (raw)
In-Reply-To: <20190826132553.4116-7-hch@lst.de>
Hi Christoph,
On Mon, Aug 26, 2019 at 03:25:53PM +0200, Christoph Hellwig wrote:
> Based on an email from Paul Burton, quoting section 4.8 "Cacheability and
> Coherency Attributes and Access Types" of "MIPS Architecture Volume 1:
> Introduction to the MIPS32 Architecture" (MD00080, revision 6.01).
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Paul Burton <paul.burton@mips.com>
Thanks,
Paul
> ---
> arch/mips/Kconfig | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index fc88f68ea1ee..aff1cadeea43 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -1119,6 +1119,13 @@ config DMA_PERDEV_COHERENT
>
> config DMA_NONCOHERENT
> bool
> + #
> + # MIPS allows mixing "slightly different" Cacheability and Coherency
> + # Attribute bits. It is believed that the uncached access through
> + # KSEG1 and the implementation specific "uncached accelerated" used
> + # by pgprot_writcombine can be mixed, and the latter sometimes provides
> + # significant advantages.
> + #
> select ARCH_HAS_DMA_WRITE_COMBINE
> select ARCH_HAS_SYNC_DMA_FOR_DEVICE
> select ARCH_HAS_UNCACHED_SEGMENT
> --
> 2.20.1
>
next prev parent reply other threads:[~2019-08-27 10:03 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-26 13:25 cleanup the dma_pgprot handling v2 Christoph Hellwig
2019-08-26 13:25 ` [PATCH 1/6] unicore32: remove the unused pgprot_dmacoherent define Christoph Hellwig
2019-08-26 13:25 ` [PATCH 2/6] arm-nommu: " Christoph Hellwig
2019-08-26 13:25 ` [PATCH 3/6] dma-mapping: remove arch_dma_mmap_pgprot Christoph Hellwig
2019-08-27 10:02 ` Paul Burton
2019-08-26 13:25 ` [PATCH 4/6] dma-mapping: make dma_atomic_pool_init self-contained Christoph Hellwig
2019-08-26 13:25 ` [PATCH 5/6] arm64: document the choice of page attributes for pgprot_dmacoherent Christoph Hellwig
2019-08-26 13:25 ` [PATCH 6/6] MIPS: document mixing "slightly different CCAs" Christoph Hellwig
2019-08-27 10:03 ` Paul Burton [this message]
2019-08-29 15:28 ` cleanup the dma_pgprot handling v2 Christoph Hellwig
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