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

[Ryan Mallon]

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

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 <ryan@xxxxxxxxxxxxxxxx>

Can you please update for the changes I suggested.

Thanks,
~Ryan

-- 
Bluewater Systems Ltd - ARM Technology Solution Centre

Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
ryan@xxxxxxxxxxxxxxxx         	PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com	New Zealand
Phone: +64 3 3779127		Freecall: Australia 1800 148 751
Fax:   +64 3 3779135			  USA 1800 261 2934
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/