linux-kernel - Re: [PATCH v2 21/65] clk: davinci: da8xx-cfgchip: Add a determine

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Message-ID: <20221107120611.vutsgpgpcorsgzwp@houat>
Date:   Mon, 7 Nov 2022 13:06:11 +0100
From:   Maxime Ripard <maxime@...no.tech>
To:     David Lechner <david@...hnology.com>
Cc:     Stephen Boyd <sboyd@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
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Subject: Re: [PATCH v2 21/65] clk: davinci: da8xx-cfgchip: Add a
 determine_rate hook

Hi David,

On Fri, Nov 04, 2022 at 11:45:17AM -0500, David Lechner wrote:
> On 11/4/22 8:17 AM, Maxime Ripard wrote:
> > The Davinci DA8xxx cfgchip mux clock implements a mux with a set_parent
> > hook, but doesn't provide a determine_rate implementation.
> > 
> > This is a bit odd, since set_parent() is there to, as its name implies,
> > change the parent of a clock. However, the most likely candidate to
> > trigger that parent change is a call to clk_set_rate(), with
> > determine_rate() figuring out which parent is the best suited for a
> > given rate.
> > 
> > The other trigger would be a call to clk_set_parent(), but it's far less
> > used, and it doesn't look like there's any obvious user for that clock.
> > 
> > So, the set_parent hook is effectively unused, possibly because of an
> > oversight. However, it could also be an explicit decision by the
> > original author to avoid any reparenting but through an explicit call to
> > clk_set_parent().
> 
> 
> The parent is defined in the device tree and is not expected to change
> at runtime, so if I am understanding the patch correctly, setting the
> CLK_SET_RATE_NO_REPARENT flag seems correct.

Is that an acked-by/reviewed-by?

Thanks!
Maxime

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