linux-kernel - Re: [PATCH RFC 1/2] clk: introduce clk_invalidate

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Date:   Thu, 26 Sep 2019 17:14:25 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Neil Armstrong <narmstrong@...libre.com>, jbrunet@...libre.com,
        mturquette@...libre.com
Cc:     Neil Armstrong <narmstrong@...libre.com>,
        linux-clk@...r.kernel.org, linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC 1/2] clk: introduce clk_invalidate_rate()

Quoting Neil Armstrong (2019-09-19 03:25:17)
> This introduces the clk_invalidate_rate() call used to recalculate the
> rate and parent tree of a particular clock if it's known that the
> underlying registers set has been altered by the firmware, like from
> a suspend/resume handler running in trusted cpu mode.
> 
> The call refreshes the actual parent and when changed, instructs CCF
> the parent has changed. Finally the call will recalculate the rate of
> each part of the tree to make sure the CCF cached tree is in sync with
> the hardware.
> 
> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
> ---

The knee-jerk reaction to these patches is that it shouldn't be a
consumer API (i.e. taking a struct clk) but a provider API (i.e. taking
a struct clk_hw). I haven't looked in any more detail but just know that
it's a non-starter to be a consumer based API because we don't want
random consumers out there to be telling the CCF or provider drivers
that some clk has lost state and needs to be "refreshed".