From: Vladimir Murzin <vladimir.murzin@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, linux@armlinux.org.uk, sza@esh.hu,
arnd@arndb.de, gregkh@linuxfoundation.org,
akpm@linux-foundation.org, alexandre.torgue@st.com,
robin.murphy@arm.com, benjamin.gaignard@linaro.org,
kbuild-all@01.org
Subject: [PATCH v5 6/7] ARM: NOMMU: Set ARM_DMA_MEM_BUFFERABLE for M-class cpus
Date: Wed, 24 May 2017 11:24:31 +0100 [thread overview]
Message-ID: <1495621472-9323-7-git-send-email-vladimir.murzin@arm.com> (raw)
In-Reply-To: <1495621472-9323-1-git-send-email-vladimir.murzin@arm.com>
Now, we have dedicated non-cacheable region for consistent DMA
operations. However, that region can still be marked as bufferable by
MPU, so it'd be safer to have barriers by default. M-class machines
that didn't need it until now also likely won't need it in the future,
therefore, we offer this as an option.
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Andras Szemzo <sza@esh.hu>
Tested-by: Alexandre TORGUE <alexandre.torgue@st.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
arch/arm/mm/Kconfig | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index d731f28..f50bbda 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -1049,8 +1049,8 @@ config ARM_L1_CACHE_SHIFT
default 5
config ARM_DMA_MEM_BUFFERABLE
- bool "Use non-cacheable memory for DMA" if (CPU_V6 || CPU_V6K) && !CPU_V7
- default y if CPU_V6 || CPU_V6K || CPU_V7
+ bool "Use non-cacheable memory for DMA" if (CPU_V6 || CPU_V6K || CPU_V7M) && !CPU_V7
+ default y if CPU_V6 || CPU_V6K || CPU_V7 || CPU_V7M
help
Historically, the kernel has used strongly ordered mappings to
provide DMA coherent memory. With the advent of ARMv7, mapping
@@ -1065,6 +1065,10 @@ config ARM_DMA_MEM_BUFFERABLE
and therefore turning this on may result in unpredictable driver
behaviour. Therefore, we offer this as an option.
+ On some of the beefier ARMv7-M machines (with DMA and write
+ buffers) you likely want this enabled, while those that
+ didn't need it until now also won't need it in the future.
+
You are recommended say 'Y' here and debug any affected drivers.
config ARM_HEAVY_MB
--
2.0.0
next prev parent reply other threads:[~2017-05-24 10:28 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 10:24 [PATCH v5 0/7] ARM: Fix dma_alloc_coherent() and friends for NOMMU Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 1/7] dma: Take into account dma_pfn_offset Vladimir Murzin
2017-06-20 13:24 ` Christoph Hellwig
2017-06-22 12:47 ` Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 2/7] dma: Add simple dma_noop_mmap Vladimir Murzin
2017-06-20 13:23 ` Christoph Hellwig
2017-06-22 12:46 ` Vladimir Murzin
2017-06-26 9:45 ` Christoph Hellwig
2017-05-24 10:24 ` [PATCH v5 3/7] drivers: dma-coherent: Account dma_pfn_offset when used with device tree Vladimir Murzin
2017-06-20 13:42 ` Christoph Hellwig
2017-06-20 13:50 ` Robin Murphy
2017-06-26 9:37 ` Christoph Hellwig
2017-06-22 12:59 ` Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Vladimir Murzin
2017-06-20 13:49 ` Christoph Hellwig
2017-06-20 14:24 ` Robin Murphy
2017-06-26 9:42 ` Christoph Hellwig
2017-06-26 14:08 ` Vladimir Murzin
2017-06-27 14:36 ` Robin Murphy
2017-06-27 15:22 ` Christoph Hellwig
2017-06-22 13:18 ` Vladimir Murzin
2017-06-26 9:44 ` Christoph Hellwig
2017-05-24 10:24 ` [PATCH v5 5/7] ARM: NOMMU: Introduce dma operations for noMMU Vladimir Murzin
2017-05-24 10:24 ` Vladimir Murzin [this message]
2017-05-24 10:24 ` [PATCH v5 7/7] ARM: dma-mapping: Remove traces of NOMMU code Vladimir Murzin
2017-06-08 8:28 ` [PATCH v5 0/7] ARM: Fix dma_alloc_coherent() and friends for NOMMU Vladimir Murzin
2017-06-08 16:25 ` Russell King - ARM Linux
2017-06-15 7:25 ` Vladimir Murzin
2017-06-20 12:59 ` Vladimir Murzin
2017-06-20 13:00 ` Christoph Hellwig
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