Re: [PATCH 08/10] ARM: dts: exynos: use proper 'dma-channels/requests' properties

From: Rob Herring
Date: Thu Apr 28 2022 - 09:33:20 EST


On Thu, Apr 28, 2022 at 12:09:02PM +0200, Krzysztof Kozlowski wrote:
> On 28/04/2022 12:05, Marek Szyprowski wrote:
> >>>>> I also don't see any code that would read those properties. IMHO they
> >>>>> should be simply removed at all, at least for the PL330 related nodes.
> >>>> In current Linux implementation they indeed are not used. Nothing parses
> >>>> them. However:
> >>>> 1. They describe (hopefully correct) the hardware.
> >>>> 2. They might be used by other implementations of pl330 driver.
> >>>>
> >>>> I would not remove them from existing sources, but indeed maybe there is
> >>>> no need to add for new files.
> >>> What's the point in having dt properties duplicating data that might be
> >>> read from the driver registers?
> >> Hm, indeed, there is no point in this. Since they are read from
> >> registers, what was the idea behind in commit 42cf20980cde?
> >
> > #dma-cells is indeed required, but the rest seems to be the cargo-cult
> > of some kind.
>
> Rob,
>
> Any guidance from your side? Is there any benefit in describing the
> hadrware (dma-channels/dma-requests) if the same value can be read from
> registers?

Drop the properties. They should only be an override if ever needed.

Rob