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

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Date:   Mon, 7 Nov 2022 08:52:56 -0600
From:   David Lechner <david@...hnology.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Stephen Boyd <sboyd@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Chen-Yu Tsai <wens@...e.org>, Daniel Vetter <daniel@...ll.ch>,
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Subject: Re: [PATCH v2 21/65] clk: davinci: da8xx-cfgchip: Add a
 determine_rate hook

On 11/7/22 6:06 AM, Maxime Ripard wrote:
> 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

The commit message could be updated to be more certain now, but sure...

Acked-by: David Lechner <david@...hnology.com>