linux-kernel - Re: [PATCH v4 2/4] arm64: dts: exynos: add initial CMU clock nodes in ExynosAuto v920

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Message-ID: <dd0449bc-f02a-4879-a7cd-e01fbea01d9f@linaro.org>
Date: Wed, 24 Jul 2024 12:17:44 +0100
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Sunyeal Hong <sunyeal.hong@...sung.com>,
 Krzysztof Kozlowski <krzk@...nel.org>,
 Sylwester Nawrocki <s.nawrocki@...sung.com>,
 Chanwoo Choi <cw00.choi@...sung.com>, Alim Akhtar <alim.akhtar@...sung.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>
Cc: linux-samsung-soc@...r.kernel.org, linux-clk@...r.kernel.org,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/4] arm64: dts: exynos: add initial CMU clock nodes in
 ExynosAuto v920

Hi, Sunyeal,

I quickly skimmed over the series and I fail to see where/how the HW
auto clock gating is enabled/configured. Would you please add more
details on how this works?

On 7/22/24 11:33 PM, Sunyeal Hong wrote:
> Add cmu_top, cmu_peric0 clock nodes and
> switch USI clocks instead of dummy fixed-rate-clock.
> 
> Signed-off-by: Sunyeal Hong <sunyeal.hong@...sung.com>
> ---
>  .../arm64/boot/dts/exynos/exynosautov920.dtsi | 40 +++++++++++++------
>  1 file changed, 27 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/exynos/exynosautov920.dtsi b/arch/arm64/boot/dts/exynos/exynosautov920.dtsi
> index c1c8566d74f5..54fc32074379 100644
> --- a/arch/arm64/boot/dts/exynos/exynosautov920.dtsi
> +++ b/arch/arm64/boot/dts/exynos/exynosautov920.dtsi


cut

> @@ -224,7 +237,8 @@ serial_0: serial@...80000 {
>  				interrupts = <GIC_SPI 764 IRQ_TYPE_LEVEL_HIGH>;
>  				pinctrl-names = "default";
>  				pinctrl-0 = <&uart0_bus>;
> -				clocks = <&clock_usi>, <&clock_usi>;
> +				clocks = <&cmu_peric0 CLK_MOUT_PERIC0_NOC_USER>,

isn't this MUX common to multiple GATEs? Wouldn't turning it off affect
other users than the serial?

Thanks,
ta

> +					 <&cmu_peric0 CLK_DOUT_PERIC0_USI00_USI>;
>  				clock-names = "uart", "clk_uart_baud0";
>  				samsung,uart-fifosize = <256>;
>  				status = "disabled";