Re: [PATCH v2 1/7] arm64: dts: qcom: sm8450: add spmi node

Bjorn Andersson
2022-12-29T16:12:55Z

On Thu, Dec 29, 2022 at 11:57:58AM +0100, Krzysztof Kozlowski wrote:
> On 29/12/2022 11:45, Konrad Dybcio wrote:
> >
> >
> > On 29.12.2022 11:42, Krzysztof Kozlowski wrote:
> >> On 29/12/2022 11:32, Konrad Dybcio wrote:
> >>> From: Vinod Koul <vkoul@kernel.org>
> >>>
> >>> Add the spmi bus as found in the SM8450 SoC
> >>>
> >>> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> >>> Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
> >>> [Konrad: 0x0 -> 0, move #cells down, make reg-names a vertical list]
> >>> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
> >>> ---
> >>> v1 -> v2:
> >>> No changes
> >>>
> >>> arch/arm64/boot/dts/qcom/sm8450.dtsi | 22 ++++++++++++++++++++++
> >>> 1 file changed, 22 insertions(+)
> >>>
> >>> diff --git a/arch/arm64/boot/dts/qcom/sm8450.dtsi b/arch/arm64/boot/dts/qcom/sm8450.dtsi
> >>> index 570475040d95..b9b59c5223eb 100644
> >>> --- a/arch/arm64/boot/dts/qcom/sm8450.dtsi
> >>> +++ b/arch/arm64/boot/dts/qcom/sm8450.dtsi
> >>> @@ -2715,6 +2715,28 @@ aoss_qmp: power-controller@c300000 {
> >>> #clock-cells = <0>;
> >>> };
> >>>
> >>> + spmi_bus: spmi@c42d000 {
> >>
> >> Hmm looks different than reg.
> >>
> >>> + compatible = "qcom,spmi-pmic-arb";
> >>> + reg = <0 0x0c400000 0 0x00003000>,
> >>> + <0 0x0c500000 0 0x00400000>,
> >>> + <0 0x0c440000 0 0x00080000>,
> >>> + <0 0x0c4c0000 0 0x00010000>,
> >>> + <0 0x0c42d000 0 0x00010000>;
> >> x
> > Hm, my guess would be that Vinod chose to put the "cnfg" reg
> > instead of "core" in the unit address, as 8450 has 2 SPMI bus
> > hosts and they both share the core reg, so it would have been
> > impossible to have two spmi@core nodes..
>
> Eh? SM8450 has 2 SPMI hosts both using 0x0c400000? How does that work?
> Usually address can be mapped only once.
>

The SPMI controller does something like multi-master. The driver expects
the same region to be mapped multiple times and qcom,channel is used to
select which one each instance should operate on.

Regards,
Bjorn

> Where is the second SPMI? I cannot find it in linux-next.
>
>
> Best regards,
> Krzysztof
>