From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 4/5] DMA: Add functions to preallocate DMA memory dor
Date: Thu, 02 Sep 2010 10:50:55 +0000 [thread overview]
Message-ID: <20100902105055.GS26319@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <Pine.LNX.4.64.1008191636590.26145@axis700.grange>
On Thu, Aug 19, 2010 at 04:40:22PM +0200, Guennadi Liakhovetski wrote:
> Currently dma_declare_coherent_memory() and dma_release_declared_memory() are
> provided to assign DMA memory to a device and to release it. These functions
> can be use with device local memory, like on-chip SRAM. However, they are
> unsuitable for assigning of generic system RAM to devices, because such system
> memory should not be ioremapped, and ioremap() is used internally in the former
> of these functions to map the memory.
>
> This patch solves this problem by adding two more functions:
> dma_preallocate_coherent_memory() and dma_release_preallocated_memory(), which
> allocate DMA coherent memory and assign it to the device, and release it back
> respectively.
This looks like a much saner interface for pre-allocating DMA memory from
system memory, rather than trying to use dma_declare_coherent_memory().
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 4/5] DMA: Add functions to preallocate DMA memory dor devices
Date: Thu, 2 Sep 2010 11:50:55 +0100 [thread overview]
Message-ID: <20100902105055.GS26319@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <Pine.LNX.4.64.1008191636590.26145@axis700.grange>
On Thu, Aug 19, 2010 at 04:40:22PM +0200, Guennadi Liakhovetski wrote:
> Currently dma_declare_coherent_memory() and dma_release_declared_memory() are
> provided to assign DMA memory to a device and to release it. These functions
> can be use with device local memory, like on-chip SRAM. However, they are
> unsuitable for assigning of generic system RAM to devices, because such system
> memory should not be ioremapped, and ioremap() is used internally in the former
> of these functions to map the memory.
>
> This patch solves this problem by adding two more functions:
> dma_preallocate_coherent_memory() and dma_release_preallocated_memory(), which
> allocate DMA coherent memory and assign it to the device, and release it back
> respectively.
This looks like a much saner interface for pre-allocating DMA memory from
system memory, rather than trying to use dma_declare_coherent_memory().
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
next prev parent reply other threads:[~2010-09-02 10:50 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-19 14:39 [PATCH 0/5] Add API for DMA memory reservation for devices Guennadi Liakhovetski
2010-08-19 14:39 ` Guennadi Liakhovetski
2010-08-19 14:40 ` [PATCH 1/5] DMA: Remove unneeded "extern" from function declarations Guennadi Liakhovetski
2010-08-19 14:40 ` Guennadi Liakhovetski
2010-08-19 14:40 ` [PATCH 2/5] DMA: dma_declare_coherent_memory() should return an Guennadi Liakhovetski
2010-08-19 14:40 ` [PATCH 2/5] DMA: dma_declare_coherent_memory() should return an error if unsupported Guennadi Liakhovetski
2010-08-19 14:40 ` [PATCH 3/5] DMA: reduce the number of memory allocations Guennadi Liakhovetski
2010-08-19 14:40 ` Guennadi Liakhovetski
2010-08-19 15:35 ` Greg KH
2010-08-19 15:35 ` Greg KH
2010-08-19 15:46 ` Guennadi Liakhovetski
2010-08-19 15:46 ` Guennadi Liakhovetski
2010-08-19 16:02 ` Greg KH
2010-08-19 16:02 ` Greg KH
2010-09-14 8:52 ` Paul Mundt
2010-09-14 8:52 ` Paul Mundt
2010-09-15 7:23 ` Guennadi Liakhovetski
2010-09-15 7:23 ` Guennadi Liakhovetski
2010-09-16 2:58 ` FUJITA Tomonori
2010-09-16 2:58 ` FUJITA Tomonori
2010-09-16 7:04 ` Russell King - ARM Linux
2010-09-16 7:04 ` Russell King - ARM Linux
2010-09-16 7:08 ` FUJITA Tomonori
2010-09-16 7:08 ` FUJITA Tomonori
2010-09-16 4:22 ` Paul Mundt
2010-09-16 4:22 ` Paul Mundt
2010-08-20 1:15 ` Michał Nazarewicz
2010-08-20 1:15 ` Michał Nazarewicz
2010-08-19 14:40 ` [PATCH 4/5] DMA: Add functions to preallocate DMA memory dor devices Guennadi Liakhovetski
2010-08-19 14:40 ` Guennadi Liakhovetski
2010-09-02 10:50 ` Russell King - ARM Linux [this message]
2010-09-02 10:50 ` Russell King - ARM Linux
2010-09-15 7:28 ` [PATCH 4/5] DMA: Add functions to preallocate DMA memory dor
2010-09-15 7:28 ` [PATCH 4/5] DMA: Add functions to preallocate DMA memory dor devices Uwe Kleine-König
2010-08-19 14:40 ` [PATCH 5/5] SH: use dma_preallocate_coherent_memory() for platform Guennadi Liakhovetski
2010-08-19 14:40 ` [PATCH 5/5] SH: use dma_preallocate_coherent_memory() for platform device memory Guennadi Liakhovetski
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