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

On 01/18/2011 02:43 PM, Xu, Hong wrote:

Hi Ryan,

quoted

-----Original Message-----
From: Ryan Mallon [mailto:ryan at bluewatersys.com]
Sent: Tuesday, January 18, 2011 6:42 AM
To: Xu, Hong
Cc: linux-mtd at lists.infradead.org; linux-arm-kernel at lists.infradead.org;
linux-kernel at vger.kernel.org; jamie at jamieiles.com; jacmet at sunsite.dk;
Ferre, Nicolas
Subject: Re: [PATCH] MTD: atmel_nand: Add DMA support to access Nandflash

root at 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.

Thanks, that fixed it.

I have tried this under 2.6.33 on a custom SAM9G45 based board with a
512MiB NAND part, with 2kB pages and 128kB blocks using both raw MTD
access and the YAFFS2 filesystem and it appears to work correctly.

Tested-by: Ryan Mallon <redacted>

Can you please update for the changes I suggested.

Thanks,
~Ryan

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