linux-kernel - Re: [PATCH] clk: sunxi: Extend the simple gates and handle the Allwinner H3

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Date:	Tue, 8 Dec 2015 08:53:54 +0100
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Jean-Francois Moine <moinejf@...e.fr>
Cc:	Rob Herring <robh@...nel.org>, devicetree@...r.kernel.org,
	Vishnu Patekar <vishnupatekar0510@...il.com>,
	Emilio López <emilio@...pez.com.ar>,
	Michael Turquette <mturquette@...libre.com>,
	Reinder de Haan <patchesrdh@...as.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com,
	Hans de Goede <hdegoede@...hat.com>,
	Chen-Yu Tsai <wens@...e.org>, Jens Kuske <jenskuske@...il.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] clk: sunxi: Extend the simple gates and handle the
 Allwinner H3

Hi Jean-Francois,

On Tue, Dec 08, 2015 at 07:42:26AM +0100, Jean-Francois Moine wrote:
> On Mon, 7 Dec 2015 08:31:02 -0600
> Rob Herring <robh@...nel.org> wrote:
> 
> > On Sun, Dec 06, 2015 at 10:04:12AM +0100, Jean-Francois Moine wrote:
> > > The H3 has a clock gate definition similar to the other Allwinner SoCs,
> > > but with a different parent clock for each single gate.
> > > 
> > > Adding the names of the parent clocks in both the source and output clocks
> > > permits the use of the simple-gates driver to define the bus gates
> > > of all known Allwinner SoCs.
> > > 
> > > Signed-off-by: Jean-Francois Moine <moinejf@...e.fr>
> > > ---
> > > This patch replaces a part of Jens Kuske's patch
> > > 	[PATCH v5 1/4] clk: sunxi: Add H3 clocks support
> > > ---
> > >  Documentation/devicetree/bindings/clock/sunxi.txt | 25 +++++++++++++++++++++++
> > >  drivers/clk/sunxi/clk-simple-gates.c              | 14 ++++++++++++-
> > >  2 files changed, 38 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
> > > index 8a47b77..5736e6d 100644
> > > --- a/Documentation/devicetree/bindings/clock/sunxi.txt
> > > +++ b/Documentation/devicetree/bindings/clock/sunxi.txt
> > > @@ -70,6 +70,7 @@ Required properties:
> > >  	"allwinner,sun8i-a23-usb-clk" - for usb gates + resets on A23
> > >  	"allwinner,sun9i-a80-usb-mod-clk" - for usb gates + resets on A80
> > >  	"allwinner,sun9i-a80-usb-phy-clk" - for usb phy gates + resets on A80
> > > +	"allwinner,sunxi-gates-clk" - simple gates
> > >  
> > >  Required properties for all clocks:
> > >  - reg : shall be the control register address for the clock.
> > > @@ -93,6 +94,12 @@ The "allwinner,sun9i-a80-mmc-config-clk" clock also requires:
> > >  - #reset-cells : shall be set to 1
> > >  - resets : shall be the reset control phandle for the mmc block.
> > >  
> > > +The "allwinner,sunxi-gates-clk" clock also requires:
> > > +- clock-names : corresponding names of the parent clocks
> > > +when the output clocks have different parents.
> > > +These names must be 4 characters long and must appear as a prefix in
> > > +the names of the output clocks. See example.
> > > +
> > 
> > I don't think you should be encoding relationships of clocks using the 
> > name strings. We describe relationships in DT via parent/child or 
> > phandles.
> 
> As you know, in the H3, each of the 49 output clock has one of the 4
> main clocks as its source.
> There are 3 options for defining the source of each clock:
> 1- all definitions are in the DT,
> 2- some definitions are in the DT, some other ones are hard-coded,
> 3- all definitions are hard-coded.

Look, we all agreed on a solution that raised all objections, but
yours.

I'm going to take Jens patch.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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