linux-kernel - Re: [PATCH 1/2] clk: clk_core

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Message-Id: <20211210011557.E13FDC341C6@smtp.kernel.org>
Date:   Thu, 09 Dec 2021 17:15:56 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH 1/2] clk: clk_core_get() can also return NULL

Quoting Stephen Boyd (2021-12-07 20:15:33)
> Nothing stops a clk controller from registering an OF clk provider
> before registering those clks with the clk framework. This is not great
> but we deal with it in the clk framework by refusing to hand out struct
> clk pointers when 'hw->core' is NULL, the indication that clk_register()
> has been called.
> 
> Within clk_core_fill_parent_index() we considered this case when a
> clk_hw pointer is referenced directly by filling in the parent cache
> with an -EPROBE_DEFER pointer when the core pointer is NULL. When we
> lookup a parent with clk_core_get() we don't care about the return value
> being NULL though, because that was considered largely impossible, but
> it's been proven now that it can be NULL if two clk providers are
> probing in parallel and the parent provider has been registered before
> the clk has. Let's check for NULL here as well and treat it the same as
> direct clk_hw references.
> 
> Signed-off-by: Stephen Boyd <sboyd@...nel.org>
> ---

Applied to clk-next