linux-kernel - Re: [PATCH] cpufreq: scmi: add COMMON

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Date:   Fri, 4 Dec 2020 14:46:47 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Linux PM list <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: scmi: add COMMON_CLK dependency

On Fri, Dec 4, 2020 at 12:38 PM Sudeep Holla <sudeep.holla@....com> wrote:
>
> On Fri, Dec 04, 2020 at 12:17:46AM +0100, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@...db.de>
> >
> > Wtihout CONFIG_COMMON_CLK, the scmi driver fails to link:
> >
> > arm-linux-gnueabi-ld: drivers/cpufreq/scmi-cpufreq.o: in function `scmi_cpufreq_probe':
> > scmi-cpufreq.c:(.text+0x20c): undefined reference to `devm_of_clk_add_hw_provider'
> > arm-linux-gnueabi-ld: scmi-cpufreq.c:(.text+0x22c): undefined reference to `of_clk_hw_simple_get'
> >
> > Add a Kconfig dependency for it.
> >
>
> There is a fix already upstream in later -rc(rc6 IIRC), I assume you are
> seeing this prior to that.
>
> Commit f943849f7206 ("cpufreq: scmi: Fix build for !CONFIG_COMMON_CLK")

Ok, I missed that during my rebase.

> Since the only dependency on CONFIG_COMMON_CLK is to satisfy OPP adding
> dummy clock provider, I avoided adding dependency on CLK for this driver
> as this works fine for !CONFIG_COMMON_CLK.

Right. I don't think it makes much difference either way, though I usually
prefer code checks to be written as

        /* dummy clock provider as needed by OPP if clocks property is used */
        if (IS_ENABLED(CONFIG_COMMON_CLK) &&
           of_find_property(dev->of_node, "#clock-cells", NULL))
                devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);

which helps readability as well as compile coverage. Doesn't matter
here either, since there are only two lines inside.

     Arnd