Re: [PATCH v2] dmaengine: rcar-dmac: don't use DMAC error interrupt

From: Geert Uytterhoeven
Date: Wed Jun 13 2018 - 07:36:58 EST

Hi Morimoto-san,

Thanks for your patch!

On Wed, Jun 13, 2018 at 10:49 AM Kuninori Morimoto
<kuninori.morimoto.gx@xxxxxxxxxxx> wrote:
> From: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
> Current rcar-dmac is using DMAC error interrupt which will handle all
> channel's error. But in this design, error handling itself will be
> issue if user want to use virtualization, multi OS, etc.
> This patch removes current DMAC error interrupt handling, and handle it
> on each channel interrupt handler.

Just wondering, what's the usage pattern where this causes a problem?
Do you plan to export part of a SYS-DMAC instance to a guest?
How to maintain host/guest isolation?

> --- a/Documentation/devicetree/bindings/dma/renesas,rcar-dmac.txt
> +++ b/Documentation/devicetree/bindings/dma/renesas,rcar-dmac.txt
> @@ -38,6 +38,7 @@ Required Properties:
> - interrupt-names: one entry for the error interrupt, named "error", plus one
> entry per channel, named "ch%u", where %u is the channel number ranging from
> zero to the number of channels minus one.
> + # "error" interrupt will be ignored, so far

Again, DT describes hardware, not software policy.
So please drop all changes to the bindings.

With that fixed:
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>




Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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