Re: [PATCH 2/3] dmaengine: sun6i: Add support for Allwinner A23 (sun8i) variant

On Wed, Sep 17, 2014 at 11:55 PM, Maxime Ripard
[off-list ref] wrote:

On Tue, Sep 16, 2014 at 10:13:27PM +0800, Chen-Yu Tsai wrote:

quoted

quoted

quoted

+     /*
+      * sun8i variant requires us to toggle an undocumented register,
+      * as seen in Allwinner's SDK.

The BSP I have has this:

static void sunxi_dma_hw_init(struct sunxi_dmadev *dev)
{
        struct sunxi_dmadev *sunxi_dev = dev;

        clk_prepare_enable(sunxi_dev->ahb_clk);
#ifdef CONFIG_ARCH_SUN8IW3
        writel(0x04, sunxi_dev->base + DMA_GATE);
#endif
}

/* All is ok, and open the clock */
sunxi_dma_hw_init(sunxi_dev);

So I guess we can say that it's not that undocumented :)

That's right. I meant undocumented in the user manual.
I did reference the SDK in the comment, didn't I? :)

So something like

writel(DMA_GATE_ENABLE, base->DMA_GATE_REG) wouldn't be too far off :)

Sure. Will also update the comment to reflect the naming.

ChenYu