From: Christoph Hellwig <hch@lst.de>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: tony@atomide.com, joro@8bytes.org, will.deacon@arm.com,
linux@armlinux.org.uk, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org,
Nicolin Chen <nicoleotsuka@gmail.com>,
robin.murphy@arm.com, Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org, m.szyprowski@samsung.com
Subject: Re: [PATCH v2 RFC/RFT 1/5] ARM: dma-mapping: Add fallback normal page allocations
Date: Thu, 2 May 2019 15:26:10 +0200 [thread overview]
Message-ID: <20190502132610.GA3107@lst.de> (raw)
In-Reply-To: <20190430152421.GE29799@arrakis.emea.arm.com>
On Tue, Apr 30, 2019 at 04:24:21PM +0100, Catalin Marinas wrote:
> My reading of the arm32 __dma_alloc() is that if the conditions are
> right for the CMA allocator (allows blocking) and there is a default CMA
> area or a per-device one, the call ends up in cma_alloc() without any
> fallback if such allocation fails. Whether this is on purpose, I'm not
> entirely sure. There are a couple of arm32 SoCs which call
> dma_declare_contiguous() or dma_contiguous_reserve_area() and a few DT
> files describing a specific CMA range (e.g. arch/arm/boot/dts/sun5i.dtsi
> with a comment that address must be kept in the lower 256MB).
>
> If ZONE_DMA is set up correctly so that cma_alloc() is (or can be made)
> interchangeable with alloc_pages(GFP_DMA) from a device DMA capability
> perspective , I think it should be fine to have such fallback.
Indeed. I missed arm32 being different from everyone else, but we
already addresses that in another thread. Sorry for misleading
everyone.
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next prev parent reply other threads:[~2019-05-02 13:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 23:01 [PATCH v2 RFC/RFT 0/5] Save single pages from CMA area Nicolin Chen
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 1/5] ARM: dma-mapping: Add fallback normal page allocations Nicolin Chen
2019-04-24 15:06 ` Christoph Hellwig
2019-04-24 15:08 ` Christoph Hellwig
2019-04-24 18:33 ` Nicolin Chen
2019-04-24 19:26 ` Christoph Hellwig
2019-04-24 19:38 ` Nicolin Chen
2019-04-30 15:24 ` Catalin Marinas
2019-05-02 13:26 ` Christoph Hellwig [this message]
2019-04-26 20:21 ` Nicolin Chen
2019-04-26 20:25 ` Christoph Hellwig
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 2/5] dma-remap: Run alloc_pages() on failure Nicolin Chen
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 3/5] iommu: amd_iommu: Add fallback normal page allocations Nicolin Chen
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 4/5] arm64: dma-mapping: " Nicolin Chen
2019-03-26 23:01 ` [PATCH v2 RFC/RFT 5/5] dma-contiguous: Do not allocate a single page from CMA area Nicolin Chen
2019-03-27 8:08 ` [PATCH v2 RFC/RFT 0/5] Save single pages " Christoph Hellwig
2019-03-27 18:42 ` Nicolin Chen
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