On 27 February 2016 at 07:45, Robert Jarzmik <[email protected]> wrote: > Ezequiel Garcia <[email protected]> writes: > >> On 12 February 2016 at 19:29, Robert Jarzmik <[email protected]> wrote: >>> When the driver is initialized in a pure device-tree platform, the >>> driver's probe fails allocating the dma channel : >>> [ 525.624435] pxa3xx-nand 43100000.nand: no resource defined for data DMA >>> [ 525.632088] pxa3xx-nand 43100000.nand: alloc nand resource failed >>> >>> The reason is that the DMA IO resource is not acquired through platform >>> resources but by OF bindings. >>> >>> Fix this by ensuring that DMA IO resources are only queried in the non >>> device-tree case. >>> >>> Fixes: 8f5ba31aa565 ("mtd: nand: pxa3xx-nand: switch to dmaengine") >>> Signed-off-by: Robert Jarzmik <[email protected]> >>> --- >>> drivers/mtd/nand/pxa3xx_nand.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c >>> index a168cbcc1086..afd487d4b67f 100644 >>> --- a/drivers/mtd/nand/pxa3xx_nand.c >>> +++ b/drivers/mtd/nand/pxa3xx_nand.c >>> @@ -1750,7 +1750,7 @@ static int alloc_nand_resource(struct platform_device >>> *pdev) >>> if (ret < 0) >>> return ret; >>> >>> - if (use_dma) { >>> + if (!np && use_dma) { >>> r = platform_get_resource(pdev, IORESOURCE_DMA, 0); >>> if (r == NULL) { >>> dev_err(&pdev->dev, >> >> Looking through the kernel tree, this change seems to be correct. >> >> However, I'm still wondering how DMA resources are obtained in the >> device-tree case. Can you explain it to me? > > In the pxa case, look at my extract in [1]. > The lines to consider are : > dmas = <&pdma 97 3>; > dma-names = "data"; > > Now have a look at the function pxad_dma_xlate() in drivers/dma/pxa_dma.c. > You'll see that the "97" ends up in the chanel drcmr, and the "3" in the > channel's prio, when the chanel is requested in the nand driver by calling > dma_request_slave_channel_compat(). In the latter case, pxad_filter_fn() is > not > used, it's the pxad_dma_xlate() which is used instead. > > Is this what you were looking for ? >
I see. That's exactly what I was missing. Acked-by: Ezequiel Garcia <[email protected]> Thanks, -- Ezequiel García, VanguardiaSur www.vanguardiasur.com.ar
