Messages in this thread |  | | | From | "Sosnowski, Maciej" <> | | Date | Wed, 22 Jul 2009 14:35:06 +0100 | | Subject | RE: [PATCH 1/2 v3] dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller |
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Nicolas Ferre wrote: > Dan Williams : >> On Fri, Jul 3, 2009 at 10:24 AM, Nicolas Ferre<nicolas.ferre@atmel.com> wrote: >>> This AHB DMA Controller (aka HDMA or DMAC on AT91 systems) is availlable on >>> at91sam9rl chip. It will be used on other products in the future. >>> >>> This first release covers only the memory-to-memory tranfer type. This is the >>> only tranfer type supported by this chip. On other products, it will be used >>> also for peripheral DMA transfer (slave API support to come). >>> >>> I used dmatest client without problem in different configurations to test it. >>> >>> Full documentation for this controller can be found in the SAM9RL datasheet: >>> http://www.atmel.com/dyn/products/product_card.asp?part_id=4243 >>> >>> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com> --- >>> v2 is here: >>> http://lkml.org/lkml/2009/6/26/104 >>> >>> v2 -> v3: >>> - initial number of descriptors to allocate for each channel raised to 64 and is now a >>> parameter >>> - ack-bit in descriptor flag comment synchronized with TXx9 dma driver >>> - atc_desc_get() when short on descriptors in pool: create one at a time >>> - allocation flag changed to GFP_ATOMIC in atc_desc_get() >>> - call to proper funtion while unmapping: use of new >>> DMA_COMPL_{SRC,DEST}_UNMAP_SINGLE flags >>> - call dma_run_dependencies() at the end of atc_chain_complete() >>> >> >> Looks good, but now I belatedly wonder if that GFP_ATOMIC should be >> GFP_NOWAIT instead? Do we really want to consume from the system >> emergency pools for these allocations (a similar fix is need for >> ioatdma and fsldma)? > > Seems sensible indeed but I know little about allocation flags. > > What do you think about including the driver and then building a patch > that fixes this flag in all allocation functions at a time. > It may add exposure to this modification and maybe encourage people to > react...
I think it's a good plan. I will prepare similar patch on allocation flags for ioatdma.
For this v3 patch:
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Regards, Maciej
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