Messages in this thread | | | From | Robert Jarzmik <> | Subject | Re: [PATCH] mtd: nand: pxa3xx_nand: fix dmaengine initialization | Date | Sat, 27 Feb 2016 11:45:23 +0100 |
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Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> writes:
> On 12 February 2016 at 19:29, Robert Jarzmik <robert.jarzmik@free.fr> 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 <robert.jarzmik@free.fr> >> --- >> 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 ?
Cheers.
-- Robert
[1] Extract of my zylonite310.dts nand0: nand@43100000 { compatible = "marvell,pxa3xx-nand"; reg = <0x43100000 90>; interrupts = <45>; clocks = <&clks CLK_NAND>; dmas = <&pdma 97 3>; dma-names = "data"; #address-cells = <1>; #size-cells = <1>; status = "disabled"; };
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