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

From Vinod Koul <vinod.koul@intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA controller
Date 2017-09-28 18:20 +0200
Message-ID <uuJHA-2JP-3@gated-at.bofh.it> (permalink)
References <utKZ3-4P8-5@gated-at.bofh.it> <utKZ3-4P8-3@gated-at.bofh.it> <uuDiO-7d1-5@gated-at.bofh.it> <uuHFM-1y2-15@gated-at.bofh.it>
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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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Re: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA  controller Vinod Koul <vinod.koul@intel.com> - 2017-09-28 11:30 +0200
  Re: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA  controller Dmitry Osipenko <digetx@gmail.com> - 2017-09-28 14:20 +0200
  Re: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA  controller Dmitry Osipenko <digetx@gmail.com> - 2017-09-28 16:10 +0200
    Re: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA  controller Dmitry Osipenko <digetx@gmail.com> - 2017-09-28 16:40 +0200
      Re: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA  controller Vinod Koul <vinod.koul@intel.com> - 2017-09-28 18:20 +0200
        Re: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA  controller Dmitry Osipenko <digetx@gmail.com> - 2017-09-28 18:40 +0200
    Re: [PATCH v1 4/5] dmaengine: Add driver for NVIDIA Tegra AHB DMA  controller Vinod Koul <vinod.koul@intel.com> - 2017-09-28 18:20 +0200

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