linux-kernel - Re: [PATCH 4/4] clk: Warn if we register a mux without determine

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Date:   Tue, 18 Oct 2022 16:34:59 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Maxime Ripard <maxime@...no.tech>, Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>
Cc:     linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH 4/4] clk: Warn if we register a mux without determine_rate

Il 18/10/22 15:52, Maxime Ripard ha scritto:
> The determine_rate hook allows to select the proper parent and its rate
> for a given clock configuration. On another hand, set_parent is there to
> change the parent of a mux.
> 
> Some clocks provide a set_parent hook but don't implement
> determine_rate. In such a case, set_parent is pretty much useless since
> the clock framework will always assume the current parent is to be used,
> and we will thus never change it.
> 
> This situation can be solved in two ways:
>    - either we don't need to change the parent, and we thus shouldn't
>      implement set_parent;
>    - or we don't want to change the parent, in this case we should set
>      CLK_SET_RATE_NO_REPARENT;
>    - or we're missing a determine_rate implementation.
> 
> The latter is probably just an oversight from the driver's author, and
> we should thus raise their awareness about the fact that the current
> state of the driver is confusing.
> 
> It's not clear at this point how many drivers are affected though, so
> let's make it a warning instead of an error for now.
> 
> Signed-off-by: Maxime Ripard <maxime@...no.tech>

That solves my concerns :-) :-)

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>