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    SubjectRe: [PATCH] MTD: atmel_nand: Add DMA support to access Nandflash
    On 01/18/2011 02:43 PM, Xu, Hong wrote:
    > Hi Ryan,
    >> -----Original Message-----
    >> From: Ryan Mallon [mailto:ryan@bluewatersys.com]
    >> Sent: Tuesday, January 18, 2011 6:42 AM
    >> To: Xu, Hong
    >> Cc: linux-mtd@lists.infradead.org; linux-arm-kernel@lists.infradead.org;
    >> linux-kernel@vger.kernel.org; jamie@jamieiles.com; jacmet@sunsite.dk;
    >> 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@bluewatersys.com>

    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@bluewatersys.com 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


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