linux-kernel - Re: [PATCH] clk: tegra: fix SMP build

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Date:   Tue, 11 Dec 2018 09:21:11 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>,
        Michael Turquette <mturquette@...libre.com>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Prashant Gaikwad <pgaikwad@...dia.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Dmitry Osipenko <digetx@...il.com>,
        Aapo Vienamo <avienamo@...dia.com>, linux-clk@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: tegra: fix SMP build

Quoting Arnd Bergmann (2018-12-11 06:35:07)
> When CONFIG_SMP is disabled, the tegra clk driver now fails to build:
> 
> drivers/clk/tegra/clk-tegra30.c: In function 'tegra30_cpu_rail_off_ready':
> drivers/clk/tegra/clk-tegra30.c:1151:19: error: implicit declaration of function 'tegra_pmc_cpu_is_powered'; did you mean 'tegra_powergate_is_powered'? [-Werror=implicit-function-declaration]
>   cpu_pwr_status = tegra_pmc_cpu_is_powered(1) ||
> 
> I don't know if tegra works without CONFIG_SMP, but we can get it to
> build by making the calls conditional, and removing the pointless
> ifdef around the declaration. The assumption now is that in a
> non-SMP system, the secondary CPUs are always disabled.
> 
> Fixes: 61866523ed6e ("clk: tegra30: Use Tegra CPU powergate helper function")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
> Not sure if this is the best solution. If you think it's not, please
> submit a different fix.

Hmm.. Is there any reason why the implementation of
tegra_pmc_cpu_is_powered() is under an ifdef CONFIG_SMP? I'd rather not
have to think about SMP or not in this clk code and have the
tegra_pmc_cpu_is_powered() function do the UP vs SMP code optimization.