Re: [PATCH] clk: prevent __of_clk_get_hw_from_provider() from returning NULL

[Stephen Boyd <sboyd@codeaurora.org>]

On 07/19, Masahiro Yamada wrote:
> The .get(_hw) callback of an OF clock provider can return a NULL
> pointer in some cases.
> 
> For example, of_clk_src_onecell_get() returns NULL for index 1 of a
> sparse array of clocks like follows:
> 
>   clk_num == 3
>   idx 0: UART clk
>   idx 1: NULL (no clk is allocated)
>   idx 2: I2C clk
> 
> In such cases, clk_get() successfully returns NULL.
> 
> A problem is that most drivers only check IS_ERR(), like follows:
> 
>   clk = devm_clk_get(dev, NULL);
>   if (IS_ERR(clk))
>           return PTR_ERR(clk);
> 
> It carries on moving forward and will probably be hit by a different
> error check with a different error message.

NULL is a valid clk pointer, so we can't really do anything here
besides rely on driver authors to do the right thing.

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