RE: [PATCH] MTD: atmel_nand: Add DMA support to access Nandflash

From: Xu, Hong
Date: Mon Jan 17 2011 - 20:44:24 EST


Hi Ryan,
> -----Original Message-----
> From: Ryan Mallon [mailto:ryan@xxxxxxxxxxxxxxxx]
> Sent: Tuesday, January 18, 2011 6:42 AM
> To: Xu, Hong
> Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; jamie@xxxxxxxxxxxxx; jacmet@xxxxxxxxxx;
> Ferre, Nicolas
> Subject: Re: [PATCH] MTD: atmel_nand: Add DMA support to access Nandflash
>
> root@snapper:~$ dmesg | grep -i dma
> [ 0.850000] atmel_nand atmel_nand: Failed to request DMA channel
> [ 0.860000] atmel_nand atmel_nand: No DMA support for NAND access.
> [ 1.530000] at_hdmac at_hdmac: Atmel AHB DMA Controller ( cpy slave ),
> 8 channels
>
>
> It looks like the registration for the DMA controller happens after the
> NAND driver probe and so the request is failing. I had a quick look, but
> I can't see anything that would change this in more recent kernels. Any
> ideas?
>
You got the point. A [Git Pull] has been sent, see
http://article.gmane.org/gmane.linux.kernel/1088240/match=dmaengine+update

In this patch, subsys_initcall will be used so DMA engine will be initialized before NAND driver.
Thanks.

BR,
Hong
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