linux-kernel - Re: [PATCH 3/5] arm64: dts: exynos: gs101: use correct clocks for usi8

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Date: Fri, 26 Jan 2024 21:22:44 -0600
From: Sam Protsenko <semen.protsenko@...aro.org>
To: André Draszik <andre.draszik@...aro.org>
Cc: peter.griffin@...aro.org, robh+dt@...nel.org, 
	krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, 
	linux-kernel@...r.kernel.org, kernel-team@...roid.com, 
	tudor.ambarus@...aro.org, willmcvicker@...gle.com, alim.akhtar@...sung.com, 
	s.nawrocki@...sung.com, tomasz.figa@...il.com, cw00.choi@...sung.com, 
	mturquette@...libre.com, sboyd@...nel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, 
	linux-clk@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 3/5] arm64: dts: exynos: gs101: use correct clocks for usi8

On Fri, Jan 26, 2024 at 6:37 PM André Draszik <andre.draszik@...aro.org> wrote:
>
> Wrong pclk clocks have been used in this usi8 instance here. For USI
> and I2C, we need the ipclk and pclk, where pclk is the bus clock.
> Without it, nothing can work.

Empty line is missing here?

> It is unclear what exactly is using USI8_USI_CLK, but it is not
> required for the IP to be operational at this stage, while pclk is.

>From [1] it looks like DIV_CLK_PERIC0_USI8_USI is a common parrent for
these two leaf gate clocks:
  1. GOUT_BLK_PERIC0_UID_RSTNSYNC_CLK_PERIC0_USI8_USI_IPCLKPORT_CLK
  2. GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_IPCLK_7

So IIUC, you replace clock #1 with clock #2 in this patch? If so, I
think that's a right move, because in my experience RSTNSYNC clocks
shouldn't be used at all for consumer IP-cores. That's why I never
added RSTNSYNC clocks in clk-exynos850 driver at all -- I only see
them useful for store/restore ops during suspend/resume.

[1] https://android.googlesource.com/kernel/gs/+/refs/tags/android-12.0.0_r0.17/drivers/soc/google/cal-if/gs101/cmucal-node.c#2793

> This also brings the DT in line with the clock names expected by the
> usi and i2c drivers.
>
> Update the DTSI accordingly.
>
> Fixes: 6d44d1a1fb62 ("arm64: dts: exynos: gs101: define USI8 with I2C configuration")
> Signed-off-by: André Draszik <andre.draszik@...aro.org>
> ---

Reviewed-by: Sam Protsenko <semen.protsenko@...aro.org>

>  arch/arm64/boot/dts/exynos/google/gs101.dtsi | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/exynos/google/gs101.dtsi b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
> index bc251e565be6..e5b665be2d62 100644
> --- a/arch/arm64/boot/dts/exynos/google/gs101.dtsi
> +++ b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
> @@ -380,7 +380,7 @@ usi8: usi@...700c0 {
>                         ranges;
>                         #address-cells = <1>;
>                         #size-cells = <1>;
> -                       clocks = <&cmu_peric0 CLK_GOUT_PERIC0_CLK_PERIC0_USI8_USI_CLK>,
> +                       clocks = <&cmu_peric0 CLK_GOUT_PERIC0_PERIC0_TOP0_PCLK_7>,
>                                  <&cmu_peric0 CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_7>;
>                         clock-names = "pclk", "ipclk";
>                         samsung,sysreg = <&sysreg_peric0 0x101c>;
> @@ -397,7 +397,7 @@ hsi2c_8: i2c@...70000 {
>                                 pinctrl-names = "default";
>                                 pinctrl-0 = <&hsi2c8_bus>;
>                                 clocks = <&cmu_peric0 CLK_GOUT_PERIC0_PERIC0_TOP0_IPCLK_7>,
> -                                        <&cmu_peric0 CLK_GOUT_PERIC0_CLK_PERIC0_USI8_USI_CLK>;
> +                                        <&cmu_peric0 CLK_GOUT_PERIC0_PERIC0_TOP0_PCLK_7>;
>                                 clock-names = "hsi2c", "hsi2c_pclk";
>                                 status = "disabled";
>                         };
> --
> 2.43.0.429.g432eaa2c6b-goog
>