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Date: Sat, 18 Jul 2009 09:01:31 -0700
Message-ID: <e9c3a7c20907180901u3670a8edy2bc5c1b5cf911ab4@mail.gmail.com>
Subject: Re: [PATCH 1/2 v3] dmaengine: at_hdmac: new driver for the Atmel AHB 
	DMA Controller
From: Dan Williams <dan.j.williams@intel.com>
To: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: maciej.sosnowski@intel.com, avictor.za@gmail.com,
       linux-arm-kernel@lists.arm.linux.org.uk, patrice.vilchez@atmel.com,
       linux-kernel@vger.kernel.org
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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)?

Thanks,
Dan
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