linux-kernel - Re: [PATCH 00/13] arm64: Allwinner A64 support based on sunxi-ng

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Message-ID: <CAGb2v66bvtY5qtkSJ_BgyPtA+Mi-3m06NwVnntcwaNnbdwYC6w@mail.gmail.com>
Date:	Mon, 1 Aug 2016 20:01:49 +0800
From:	Chen-Yu Tsai <wens@...e.org>
To:	Jean-Francois Moine <moinejf@...e.fr>
Cc:	Chen-Yu Tsai <wens@...e.org>,
	André Przywara <andre.przywara@....com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Rob Herring <robh+dt@...nel.org>,
	Mike Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	devicetree <devicetree@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-clk <linux-clk@...r.kernel.org>
Subject: Re: [PATCH 00/13] arm64: Allwinner A64 support based on sunxi-ng

On Mon, Aug 1, 2016 at 8:00 PM, Jean-Francois Moine <moinejf@...e.fr> wrote:
> On Mon, 1 Aug 2016 17:13:34 +0800
> Chen-Yu Tsai <wens@...e.org> wrote:
>
>> > But I don't see why you are keeping the simple-gates. The bus gate may
>> > be ungated/gated when the clock is enabled/disabled, and that's what
>> > Allwinner's software does.
>>
>> For peripherals that have a separate mod clock, having them separate
>> is a good thing. One example might be the audio codecs. You could ungate
>> the bus gate to access its registers to program it, but only enable
>> the mod clock when you actually play something.
>
> The roles of the bus gate and the clock gate are the same. I don't see
> any reason to set one gate without setting the other one. More, the
> spec says what the bus gate must be enabled before the clock gate (and
> reverse order while disabling). So, setting both gates in one function
> call seems safer.

Wha? Aren't bus gates and clock gates the same thing in this context?

ChenYu

> Then, if you want to save some power while not playing anything, just do
> clk_disable() of the (main and only) i2s clock.
>
> --
> Ken ar c'hentañ |             ** Breizh ha Linux atav! **
> Jef             |               http://moinejf.free.fr/