From: Catalin Marinas <catalin.marinas@arm.com>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: 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,
Will Deacon <will@kernel.org>,
phill@raspberryi.org, f.fainelli@gmail.com,
linux-kernel@vger.kernel.org, robh+dt@kernel.org,
eric@anholt.net, mbrugger@suse.com, akpm@linux-foundation.org,
frowand.list@gmail.com, m.szyprowski@samsung.com,
linux-rpi-kernel@lists.infradead.org
Subject: Re: [PATCH 5/8] arm64: use ZONE_DMA on DMA addressing limited devices
Date: Wed, 31 Jul 2019 18:07:42 +0100 [thread overview]
Message-ID: <20190731170742.GC17773@arrakis.emea.arm.com> (raw)
In-Reply-To: <20190731154752.16557-6-nsaenzjulienne@suse.de>
On Wed, Jul 31, 2019 at 05:47:48PM +0200, Nicolas Saenz Julienne wrote:
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 1c4ffabbe1cb..f5279ef85756 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -50,6 +50,13 @@
> s64 memstart_addr __ro_after_init = -1;
> EXPORT_SYMBOL(memstart_addr);
>
> +/*
> + * We might create both a ZONE_DMA and ZONE_DMA32. ZONE_DMA is needed if there
> + * are periferals unable to address the first naturally aligned 4GB of ram.
> + * ZONE_DMA32 will be expanded to cover the rest of that memory. If such
> + * limitations doesn't exist only ZONE_DMA32 is created.
> + */
Shouldn't we instead only create ZONE_DMA to cover the whole 32-bit
range and leave ZONE_DMA32 empty? Can__GFP_DMA allocations fall back
onto ZONE_DMA32?
--
Catalin
next prev parent reply other threads:[~2019-07-31 17:07 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 [this message]
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 ` [PATCH 8/8] mm: comment arm64's usage of 'enum zone_type' Nicolas Saenz Julienne
2019-08-01 14:08 ` Christoph Hellwig
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