From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: catalin.marinas@arm.com, hch@lst.de, wahrenst@gmx.net,
marc.zyngier@arm.com, Robin Murphy <robin.murphy@arm.com>,
linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
iommu@lists.linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Cc: phill@raspberryi.org, f.fainelli@gmail.com, will@kernel.org,
robh+dt@kernel.org, eric@anholt.net, mbrugger@suse.com,
nsaenzjulienne@suse.de, akpm@linux-foundation.org,
frowand.list@gmail.com, m.szyprowski@samsung.com,
linux-rpi-kernel@lists.infradead.org
Subject: [PATCH 8/8] mm: comment arm64's usage of 'enum zone_type'
Date: Wed, 31 Jul 2019 17:47:51 +0200 [thread overview]
Message-ID: <20190731154752.16557-9-nsaenzjulienne@suse.de> (raw)
In-Reply-To: <20190731154752.16557-1-nsaenzjulienne@suse.de>
arm64 uses both ZONE_DMA and ZONE_DMA32 for the same reasons x86_64
does: peripherals with different DMA addressing limitations. This
updates both ZONE_DMAs comments to inform about the usage.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
include/linux/mmzone.h | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d77d717c620c..8fa6bcf72e7c 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -365,23 +365,24 @@ enum zone_type {
*
* Some examples
*
- * Architecture Limit
- * ---------------------------
- * parisc, ia64, sparc <4G
- * s390, powerpc <2G
- * arm Various
- * alpha Unlimited or 0-16MB.
+ * Architecture Limit
+ * ----------------------------------
+ * parisc, ia64, sparc, arm64 <4G
+ * s390, powerpc <2G
+ * arm Various
+ * alpha Unlimited or 0-16MB.
*
* i386, x86_64 and multiple other arches
- * <16M.
+ * <16M.
*/
ZONE_DMA,
#endif
#ifdef CONFIG_ZONE_DMA32
/*
- * x86_64 needs two ZONE_DMAs because it supports devices that are
- * only able to do DMA to the lower 16M but also 32 bit devices that
- * can only do DMA areas below 4G.
+ * x86_64 and arm64 need two ZONE_DMAs because they support devices
+ * that are only able to DMA a fraction of the 32 bit addressable
+ * memory area, but also devices that are limited to that whole 32 bit
+ * area.
*/
ZONE_DMA32,
#endif
--
2.22.0
next prev parent reply other threads:[~2019-07-31 15:48 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-31 15:47 [PATCH 0/8] Raspberry Pi 4 DMA addressing support Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 1/8] arm64: mm: use arm64_dma_phys_limit instead of calling max_zone_dma_phys() Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 2/8] arm64: rename variables used to calculate ZONE_DMA32's size Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 3/8] of/fdt: add function to get the SoC wide DMA addressable memory size Nicolas Saenz Julienne
2019-08-02 17:17 ` Rob Herring
2019-08-05 16:03 ` Nicolas Saenz Julienne
2019-08-05 19:23 ` Rob Herring
2019-08-06 18:12 ` Nicolas Saenz Julienne
2019-08-08 15:02 ` Rob Herring
2019-08-08 17:30 ` Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 4/8] arm64: re-introduce max_zone_dma_phys() Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 5/8] arm64: use ZONE_DMA on DMA addressing limited devices Nicolas Saenz Julienne
2019-07-31 17:07 ` Catalin Marinas
2019-08-01 15:44 ` Nicolas Saenz Julienne
2019-08-01 16:07 ` Robin Murphy
2019-08-01 16:40 ` Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 6/8] dma-direct: turn ARCH_ZONE_DMA_BITS into a variable Nicolas Saenz Julienne
2019-08-01 14:04 ` Christoph Hellwig
2019-08-01 15:59 ` Nicolas Saenz Julienne
2019-07-31 15:47 ` [PATCH 7/8] arm64: update arch_zone_dma_bits to fine tune dma-direct min mask Nicolas Saenz Julienne
2019-07-31 15:47 ` Nicolas Saenz Julienne [this message]
2019-08-01 14:08 ` [PATCH 8/8] mm: comment arm64's usage of 'enum zone_type' Christoph Hellwig
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