Re: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA controller

[Vinod Koul]

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