Re: [PATCH 1/2] dma: shdma: fix runtime PM: clear channel buffers on reset

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On Wed, Jan 04, 2012 at 03:34:17PM +0100, Guennadi Liakhovetski wrote:
> On platforms, supporting power domains, if the domain, containing a DMAC
> instance is powered down, the driver fails to resume correctly. On those
> platforms DMAC channels have an additional CHCLR register for clearing
> channel buffers. Using this register during runtime resume fixes the
> problem.
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>


> @@ -139,6 +157,10 @@ static int sh_dmae_rst(struct sh_dmae_device *shdev)
>  		dev_warn(shdev->, "Can't initialize DMAOR.\n");
>  		return -EIO;
>  	}
> +	if (shdev->pdata->dmaor_init & ~dmaor)
> +		dev_warn(shdev->,
> +			 "DMAOR=0x%x hasn't latched the initial value 0x%x.\n",
> +			 dmaor, shdev->pdata->dmaor_init);
>  	return 0;
>  }
I've just hit this on SH7786, which I suspect means that I've got it
wired up incorrectly somehow. This hunk also appears completely unrelated
to the changelog, so I'm wondering what exactly it's for. If this is a
probe attempt then presumably we should be handing down an error and
-ENODEV'ing in the init path? Is it expected that this is non-fatal in
the other reset cases?
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