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Subject: Re: [PATCH] devfreq: tegra20: add COMMON_CLK dependency
To:     Arnd Bergmann <arnd@arndb.de>,
        MyungJoo Ham <myungjoo.ham@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>
Cc:     Chanwoo Choi <cw00.choi@samsung.com>, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20190628103232.2467959-1-arnd@arndb.de>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <c2701295-0fd6-c5ec-59d4-6e6b3b3bdb8e@gmail.com>
Date:   Fri, 28 Jun 2019 14:00:58 +0300
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28.06.2019 13:32, Arnd Bergmann пишет:
> Compile-testing the new driver on platforms without CONFIG_COMMON_CLK
> leads to a link error:
> 
> drivers/devfreq/tegra20-devfreq.o: In function `tegra_devfreq_target':
> tegra20-devfreq.c:(.text+0x288): undefined reference to `clk_set_min_rate'
> 
> Add a dependency on COMMON_CLK to avoid this.
> 
> Fixes: 1d39ee8dad6d ("PM / devfreq: Introduce driver for NVIDIA Tegra20")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/devfreq/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> index f3b242987fd9..defe1d438710 100644
> --- a/drivers/devfreq/Kconfig
> +++ b/drivers/devfreq/Kconfig
> @@ -107,6 +107,7 @@ config ARM_TEGRA_DEVFREQ
>  config ARM_TEGRA20_DEVFREQ
>  	tristate "NVIDIA Tegra20 DEVFREQ Driver"
>  	depends on (TEGRA_MC && TEGRA20_EMC) || COMPILE_TEST
> +	depends on COMMON_CLK
>  	select DEVFREQ_GOV_SIMPLE_ONDEMAND
>  	select PM_OPP
>  	help
> 

How is it possible to happen? There is a stub for clk_set_min_rate() when COMMON_CLK
is disabled .. Could you please show the kernel's config that causes the problem?

Moreover that was me who added the missing stub for clk_set_min_rate() in [1] to fix [2].

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/include/linux/clk.h?id=b88c9f4129dcec941e5a26508e991c08051ed1ac

[2] https://lists.01.org/pipermail/kbuild-all/2019-April/060292.html

So this patch looks wrong to me because apparently it fixes a non-existent problem.