linux-kernel - Re: [PATCH 2/4] arm64: dts: exynos: gs101: add chipid node

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Date: Mon, 5 Feb 2024 14:36:48 +0000
From: Peter Griffin <peter.griffin@...aro.org>
To: Alexey Klimov <alexey.klimov@...aro.org>
Cc: krzysztof.kozlowski@...aro.org, alim.akhtar@...sung.com, 
	linux-samsung-soc@...r.kernel.org, semen.protsenko@...aro.org, 
	robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, 
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, klimov.linux@...il.com, kernel-team@...roid.com, 
	tudor.ambarus@...aro.org, andre.draszik@...aro.org, saravanak@...gle.com, 
	willmcvicker@...gle.com, arnd@...db.de
Subject: Re: [PATCH 2/4] arm64: dts: exynos: gs101: add chipid node

Hi Alexey & Krysztof,

On Thu, 1 Feb 2024 at 17:22, Alexey Klimov <alexey.klimov@...aro.org> wrote:
>
> Signed-off-by: Alexey Klimov <alexey.klimov@...aro.org>
> ---
>  arch/arm64/boot/dts/exynos/google/gs101.dtsi | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/exynos/google/gs101.dtsi b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
> index d838e3a7af6e..156fec2575bc 100644
> --- a/arch/arm64/boot/dts/exynos/google/gs101.dtsi
> +++ b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
> @@ -283,6 +283,11 @@ soc: soc@0 {
>                 #size-cells = <1>;
>                 ranges = <0x0 0x0 0x0 0x40000000>;
>
> +               chipid@...00000 {
> +                       compatible = "google,gs101-chipid";
> +                       reg = <0x10000000 0xd000>;
> +               };
> +

I was wondering about the 0xd000 size here, as most upstream platforms
use a chipid size of 0x100 or 0x24. I see the downstream gs101 kernel
also uses 0xd000. Looking a bit more, that is because gs-chipid.c also
has support for dumping other areas of the OTP SFR bank like asv table
(offset 0x9000) hpm_asv (offset 0xa000) and hw_tune (0xc000).

I checked Exynos850 and that also has ASV tables at those same offsets
above, but it currently uses a chipid size of 0x100 upstream.
Exynos-asv.c driver is part of exynos-chipid.c upstream so it seems
reasonable to have the increased size including those SFR registers.
Currently exynos-asv.c driver only supports Exynos5422 upstream.

@Krzysztof - From a process PoV what is the best/correct thing to do
here? Have the increased size in DT that includes ASV parts of the OTP
bank from the get-go?

Thanks,

Peter.