Re: [PATCH v2 65/65] clk: Warn if we register a mux without determine_rate

From: Charles Keepax <ckeepax@opensource.cirrus.com>
To: Maxime Ripard <maxime@cerno.tech>
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Subject: Re: [PATCH v2 65/65] clk: Warn if we register a mux without determine_rate
Date: Mon, 7 Nov 2022 10:56:53 +0000	[thread overview]
Message-ID: <20221107105653.GE10437@ediswmail.ad.cirrus.com> (raw)
In-Reply-To: <20221018-clk-range-checks-fixes-v2-65-f6736dec138e@cerno.tech>

On Fri, Nov 04, 2022 at 02:18:22PM +0100, Maxime Ripard wrote:
> 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.
> 

Commit message could probably use updated to make the new state
of the chain.

Thanks,
Charles