linux-kernel - Re: [PATCH RFC 0/2] clk: meson: g12a: handle clock hw changes while in suspend

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Date:   Fri, 27 Sep 2019 08:38:38 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Kevin Hilman <khilman@...libre.com>, sboyd@...nel.org,
        jbrunet@...libre.com, mturquette@...libre.com
Cc:     linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RFC 0/2] clk: meson: g12a: handle clock hw changes while
 in suspend

On 26/09/2019 22:46, Kevin Hilman wrote:
> Neil Armstrong <narmstrong@...libre.com> writes:
> 
>> This serie aime to support when the suspend/resume firmware alters the
>> clock tree, leading to an incorrect representation of the clock tree
>> after a resume from suspend-to-mem.
>>
>> For the Amlogic G12A/G12B/SM1 case, the SCPI firmware handling suspend
>> alters the CPU clock tree in various ways.
>>
>> Since we know which part of the tree is possibly altered, we introduce here
>> the clk_invalidate_rate() function that will rebuild the tree from the
>> hardware registers in case parents and dividers have changed.
>>
>> Finally we call clk_invalidate_rate() from a new resume callback to refresh
>> the CPU clock tree after a resume.
>>
>> With the clock tree refreshed, CCF can now handle the new clock tree
>> configuration and avoid crashing the system on further DVFS set_rates.
> 
> For clarification, does this series work without the other proposed
> fixes[1]?  or is this dependent on that?
> 
> Kevin
> 
> [1] https://lore.kernel.org/linux-amlogic/20190919093627.21245-1-narmstrong@baylibre.com/
> 

These are independent, but you'll need both to have suspend/resume fully working.

Neil