From: hch@infradead.org (Christoph Hellwig)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool
Date: Mon, 26 Jun 2017 02:44:10 -0700 [thread overview]
Message-ID: <20170626094410.GC21570@infradead.org> (raw)
In-Reply-To: <94e57caa-e7b9-d740-bca3-89950c10033e@arm.com>
On Thu, Jun 22, 2017 at 02:18:48PM +0100, Vladimir Murzin wrote:
> It is how it has been started [1] - defining memory which is not cacheable
> (i.e. suitable for coherent allocations) and building custom allocator on top
> of it, like it was done for c6x and blackfin. The annoying thing was that we
> needed to advertise such memory via command line parameter plus some "mem="
> adjustment to hide coherent memory from buddy allocator. So it was suggested
> to use reserved memory and this makes things look much better, but on the
> other hand require changes on dts side to "bind" devices with reserved memory
> - default DMA pool removes such drawback.
I like the idea in general, I'm just worried about the overlap with the
per-device coherent memory, especially when we have slight semantic
mismatches like the one about the physical (or rather dma) address
earlier.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-arm-kernel@lists.infradead.org,
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, Michal Nazarewicz <mina86@mina86.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool
Date: Mon, 26 Jun 2017 02:44:10 -0700 [thread overview]
Message-ID: <20170626094410.GC21570@infradead.org> (raw)
In-Reply-To: <94e57caa-e7b9-d740-bca3-89950c10033e@arm.com>
On Thu, Jun 22, 2017 at 02:18:48PM +0100, Vladimir Murzin wrote:
> It is how it has been started [1] - defining memory which is not cacheable
> (i.e. suitable for coherent allocations) and building custom allocator on top
> of it, like it was done for c6x and blackfin. The annoying thing was that we
> needed to advertise such memory via command line parameter plus some "mem="
> adjustment to hide coherent memory from buddy allocator. So it was suggested
> to use reserved memory and this makes things look much better, but on the
> other hand require changes on dts side to "bind" devices with reserved memory
> - default DMA pool removes such drawback.
I like the idea in general, I'm just worried about the overlap with the
per-device coherent memory, especially when we have slight semantic
mismatches like the one about the physical (or rather dma) address
earlier.
next prev parent reply other threads:[~2017-06-26 9:44 UTC|newest]
Thread overview: 60+ 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 ` Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 1/7] dma: Take into account dma_pfn_offset Vladimir Murzin
2017-05-24 10:24 ` Vladimir Murzin
2017-06-20 13:24 ` Christoph Hellwig
2017-06-20 13:24 ` Christoph Hellwig
2017-06-22 12:47 ` Vladimir Murzin
2017-06-22 12:47 ` Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 2/7] dma: Add simple dma_noop_mmap Vladimir Murzin
2017-05-24 10:24 ` Vladimir Murzin
2017-06-20 13:23 ` Christoph Hellwig
2017-06-20 13:23 ` Christoph Hellwig
2017-06-22 12:46 ` Vladimir Murzin
2017-06-22 12:46 ` Vladimir Murzin
2017-06-26 9:45 ` Christoph Hellwig
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
2017-05-24 10:24 ` Vladimir Murzin
2017-06-20 13:42 ` Christoph Hellwig
2017-06-20 13:42 ` Christoph Hellwig
2017-06-20 13:50 ` Robin Murphy
2017-06-20 13:50 ` Robin Murphy
2017-06-26 9:37 ` Christoph Hellwig
2017-06-26 9:37 ` Christoph Hellwig
2017-06-22 12:59 ` Vladimir Murzin
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
2017-05-24 10:24 ` Vladimir Murzin
2017-06-20 13:49 ` Christoph Hellwig
2017-06-20 13:49 ` Christoph Hellwig
2017-06-20 14:24 ` Robin Murphy
2017-06-20 14:24 ` Robin Murphy
2017-06-26 9:42 ` Christoph Hellwig
2017-06-26 9:42 ` Christoph Hellwig
2017-06-26 14:08 ` Vladimir Murzin
2017-06-26 14:08 ` Vladimir Murzin
2017-06-27 14:36 ` Robin Murphy
2017-06-27 14:36 ` Robin Murphy
2017-06-27 15:22 ` Christoph Hellwig
2017-06-27 15:22 ` Christoph Hellwig
2017-06-22 13:18 ` Vladimir Murzin
2017-06-22 13:18 ` Vladimir Murzin
2017-06-26 9:44 ` Christoph Hellwig [this message]
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
2017-05-24 10:24 ` [PATCH v5 6/7] ARM: NOMMU: Set ARM_DMA_MEM_BUFFERABLE for M-class cpus Vladimir Murzin
2017-05-24 10:24 ` Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 7/7] ARM: dma-mapping: Remove traces of NOMMU code Vladimir Murzin
2017-05-24 10:24 ` 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 8:28 ` Vladimir Murzin
2017-06-08 16:25 ` Russell King - ARM Linux
2017-06-08 16:25 ` Russell King - ARM Linux
2017-06-15 7:25 ` Vladimir Murzin
2017-06-15 7:25 ` Vladimir Murzin
2017-06-20 12:59 ` Vladimir Murzin
2017-06-20 12:59 ` Vladimir Murzin
2017-06-20 13:00 ` Christoph Hellwig
2017-06-20 13:00 ` Christoph Hellwig
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