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Subject: Re: [PATCH] MIPS: ralink: define stubs for clk_set_parent to fix
 compile testing
To:     Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        John Crispin <john@phrozen.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     thierry.reding@gmail.com, linux-tegra@vger.kernel.org,
        balbi@kernel.org, linux-usb@vger.kernel.org,
        kernel test robot <lkp@intel.com>
References: <20210316175725.79981-1-krzysztof.kozlowski@canonical.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <44ce8a32-91ff-bb6c-adba-f85c2edf3c18@gmail.com>
Date:   Wed, 17 Mar 2021 03:10:03 +0300
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16.03.2021 20:57, Krzysztof Kozlowski пишет:
> The Ralink MIPS platform does not use Common Clock Framework and does
> not define certain clock operations leading to compile test failures:
> 
>     /usr/bin/mips-linux-gnu-ld: drivers/usb/phy/phy-tegra-usb.o: in function `tegra_usb_phy_init':
>     phy-tegra-usb.c:(.text+0x1dd4): undefined reference to `clk_get_parent'
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
> ---
>  arch/mips/ralink/clk.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/arch/mips/ralink/clk.c b/arch/mips/ralink/clk.c
> index 2f9d5acb38ea..8387177a47ef 100644
> --- a/arch/mips/ralink/clk.c
> +++ b/arch/mips/ralink/clk.c
> @@ -70,6 +70,20 @@ long clk_round_rate(struct clk *clk, unsigned long rate)
>  }
>  EXPORT_SYMBOL_GPL(clk_round_rate);
>  
> +int clk_set_parent(struct clk *clk, struct clk *parent)
> +{
> +	WARN_ON(clk);
> +	return -1;
> +}
> +EXPORT_SYMBOL(clk_set_parent);
> +
> +struct clk *clk_get_parent(struct clk *clk)
> +{
> +	WARN_ON(clk);
> +	return NULL;
> +}
> +EXPORT_SYMBOL(clk_get_parent);

I'm wondering whether symbols should be GPL or it doesn't matter in this
case. Otherwise this looks good to me.

Also, I guess it should be possible to create a generic clk stubs that
will use weak functions, allowing platforms to override only the wanted
stubs and then we won't need to worry about the missing stubs for each
platform individually. But of course that will be a much bigger change.
Just wanted to share my thoughts.