linux-kernel - Re: [PATCH] clk: rockchip: Set "ignore unused" for PMU M0 clocks on rk3399

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Date:   Wed, 15 Feb 2017 18:01:25 +0100
From:   Heiko Stübner <heiko@...ech.de>
To:     Javier Martinez Canillas <javier@...hile0.org>
Cc:     Douglas Anderson <dianders@...omium.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        jwerner@...omium.org, hl@...k-chips.com, dbasehore@...omium.org,
        zhengxing@...k-chips.com,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>, linux-clk@...r.kernel.org,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clk: rockchip: Set "ignore unused" for PMU M0 clocks on rk3399

Am Mittwoch, 15. Februar 2017, 12:27:59 CET schrieb Javier Martinez Canillas:
> Hello Doug,
> 
> On Tue, Feb 14, 2017 at 6:01 PM, Douglas Anderson <dianders@...omium.org> 
wrote:
> > The PMU Cortex M0 on rk3399 is intended to be used for things like
> > DDRFreq transitions, suspend/resume, and other things that are the
> > purview of ARM Trusted Firmware and not the kernel.  As such, the
> > kernel shouldn't be messing with the clocks.  Add CLK_IGNORE_UNUSED to
> > these clocks.
> 
> Isn't CLK_IS_CRITICAL a more suitable flag for this case?

>From the patch description it looks like the clock is expected to be 
controlled from firmware in most cases as I guess the Cortex M0 will be used 
for that all the time now. And the clock is not expected to run all the time.

So I'd think clk_ignore_unused is the correct one. The whole clock-subtree for 
these clocks also does not get affected by other clocks, as it is 
independendly coming from PLLs.


Heiko