From mboxrd@z Thu Jan 1 00:00:00 1970 From: ryan@bluewatersys.com (Ryan Mallon) Date: Tue, 18 Jan 2011 15:44:58 +1300 Subject: [PATCH] MTD: atmel_nand: Add DMA support to access Nandflash In-Reply-To: <4C79549CB6F772498162A641D92D5328D9FE16@penmb01.corp.atmel.com> References: <1295248809-30334-2-git-send-email-hong.xu@atmel.com> <4D34A37E.1060300@bluewatersys.com> <4D34C5BF.2070107@bluewatersys.com> <4C79549CB6F772498162A641D92D5328D9FE16@penmb01.corp.atmel.com> Message-ID: <4D34FEAA.3000402@bluewatersys.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 01/18/2011 02:43 PM, Xu, Hong wrote: > Hi Ryan, >> -----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 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 at 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