Re: [PATCH 1/2] arm64: dts: mt8173: elm: Set uart0 to mmio32 iotype

[Hsin-Yi Wang <hsinyi@chromium.org>]

On Thu, Sep 10, 2020 at 4:16 PM Enric Balletbo i Serra
<enric.balletbo@collabora.com> wrote:
>
> Hi Hsin-Yi,
>
> On 10/9/20 9:57, Hsin-Yi Wang wrote:
> > On Thu, Sep 10, 2020 at 3:20 PM Enric Balletbo i Serra
> > <enric.balletbo@collabora.com> wrote:
> >>
> >> Hi Hsin-Yi,
> >>
> >> On 10/9/20 7:46, Hsin-Yi Wang wrote:
> >>> Set uart0 iotype to mmio32 to make earlycon work with stdout-path.
> >>>
> >>> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> >>> ---
> >>>  arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi | 2 ++
> >>>  1 file changed, 2 insertions(+)
> >>>
> >>> diff --git a/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi b/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi
> >>> index a5a12b2599a4a..d54e62f72c65d 100644
> >>> --- a/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi
> >>> +++ b/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi
> >>> @@ -1160,6 +1160,8 @@ &thermal {
> >>>  };
> >>>
> >>>  &uart0 {
> >>> +     reg-io-width = <4>;
> >>> +     reg-shift = <2>;
> >>
> >> I am wondering if these properties are common enough to go to mt8173.dtsi
> >> instead of here.
> >>
> > Since stdout-path is set on elm.dtsi (using uart0), so I add this
> > attribute here.
> >
>
> Why needs to be defined in the same place that stdout-path is set?
>
> My guess is that reg-io-width and reg-shift are SoC specific, as they define how
> the IO access to the register is done. In fact, I think that these properties
> should be added in all the uarts, not only the one that has defined the stdout-path.
>
Okay, I'll apply them to all uart. Thanks.