linux-kernel - Re: [PATCH] clk: exynos7: Mark aclk_fsys1

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Message-ID: <53be0d9d-a64a-9108-85f0-40ac360757c4@kernel.org>
Date:   Wed, 7 Apr 2021 12:03:39 +0200
From:   Sylwester Nawrocki <snawrocki@...nel.org>
To:     Paweł Chmiel <pawel.mikolaj.chmiel@...il.com>
Cc:     s.nawrocki@...sung.com, tomasz.figa@...il.com,
        cw00.choi@...sung.com, linux-samsung-soc@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, kgene@...nel.org, krzk@...nel.org,
        mturquette@...libre.com, sboyd@...nel.org
Subject: Re: [PATCH] clk: exynos7: Mark aclk_fsys1_200 as critical

On 24.10.2020 17:43, Paweł Chmiel wrote:
> This clock must be always enabled to allow access to any registers in
> fsys1 CMU. Until proper solution based on runtime PM is applied
> (similar to what was done for Exynos5433), mark that clock as critical
> so it won't be disabled.
> 
> It was observed on Samsung Galaxy S6 device (based on Exynos7420), where
> UFS module is probed before pmic used to power that device.
> In this case defer probe was happening and that clock was disabled by
> UFS driver, causing whole boot to hang on next CMU access.
> 
> Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@...il.com>
> ---
>   drivers/clk/samsung/clk-exynos7.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/samsung/clk-exynos7.c b/drivers/clk/samsung/clk-exynos7.c
> index c1ff715e960c..1048d83f097b 100644
> --- a/drivers/clk/samsung/clk-exynos7.c
> +++ b/drivers/clk/samsung/clk-exynos7.c
> @@ -538,7 +538,8 @@ static const struct samsung_gate_clock top1_gate_clks[] __initconst = {
>   		ENABLE_ACLK_TOP13, 28, CLK_SET_RATE_PARENT |
>   		CLK_IS_CRITICAL, 0),

As this patch can be backported up to the commit that introduced regression
I have applied it instead of your v3, with a comment as below.

+       /*
+        * This clock is required for the CMU_FSYS1 registers access, keep it
+        * enabled permanently until proper runtime PM support is added.
+        */

>   	GATE(CLK_ACLK_FSYS1_200, "aclk_fsys1_200", "dout_aclk_fsys1_200",
> -		ENABLE_ACLK_TOP13, 24, CLK_SET_RATE_PARENT, 0),
> +		ENABLE_ACLK_TOP13, 24, CLK_SET_RATE_PARENT |
> +		CLK_IS_CRITICAL, 0),
>   
>   	GATE(CLK_SCLK_PHY_FSYS1_26M, "sclk_phy_fsys1_26m",
>   		"dout_sclk_phy_fsys1_26m", ENABLE_SCLK_TOP1_FSYS11,
  
--
Regards,
Sylwester