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SubjectRe: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA controller
On Thu, Sep 28, 2017 at 05:06:03PM +0300, Dmitry Osipenko wrote:
> On 28.09.2017 12:29, Vinod Koul wrote:
> >> + default:
> >> + return -EINVAL;
> >> + }
> >> +
> >> + ahb_seq = burst << TEGRA_AHBDMA_CHANNEL_AHB_BURST_SHIFT;
> >> + ahb_seq |= TEGRA_AHBDMA_CHANNEL_ADDR_WRAP;
> >> + ahb_seq |= TEGRA_AHBDMA_CHANNEL_INTR_ENB;
> >> +
> >> + writel_relaxed(ahb_seq,
> >> + ahbdma_chan->regs + TEGRA_AHBDMA_CHANNEL_AHB_SEQ);
> >> +
> >> + writel_relaxed(ahb_addr,
> >> + ahbdma_chan->regs + TEGRA_AHBDMA_CHANNEL_AHB_PTR);
> >
> > oh no, you don't write to HW here. This can be called anytime when you have
> > txn running! You should save these and use them in prep_ calls.
> >
>
> BTW, some of the DMA drivers have exactly the same problem. I now see that it is
> actually documented explicitly in provider.txt, but that's inconsistent across
> the actual drivers.

yeah they need to be fixed!

--
~Vinod

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