From: s.nawrocki@samsung•com (Sylwester Nawrocki)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH RFC v4 2/2] clk: Add handling of clk parent and rate assigned from DT
Date: Tue, 01 Apr 2014 11:31:57 +0200 [thread overview]
Message-ID: <533A878D.8080302@samsung.com> (raw)
In-Reply-To: <20140401062306.GS17250@pengutronix.de>
On 01/04/14 08:23, Sascha Hauer wrote:
>> tree/bindings/clock/clock-bindings.txt
>> > b/Documentation/devicetree/bindings/clock/clock-bindings.txt
>>> > >index 700e7aa..59fbb4e 100644
>>> > >--- a/Documentation/devicetree/bindings/clock/clock-bindings.txt
>>> > >+++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt
>>> > >@@ -132,3 +132,45 @@ clock signal, and a UART.
>>> > > ("pll" and "pll-switched").
>>> > > * The UART has its baud clock connected the external oscillator and its
>>> > > register clock connected to the PLL clock (the "pll-switched" signal)
>>> > >+
>>> > >+==Assigned clock parents and rates==
>>> > >+
>>> > >+Some platforms require static initial configuration of parts of the clocks
>>> > >+controller. Such a configuration can be specified in a clock consumer node
>>> > >+through clock-parents and clock-rates DT properties. The former should
>>> > >+contain a list of parent clocks in form of phandle and clock specifier pairs,
>>> > >+the latter the list of assigned clock frequency values (one cell each).
>>> > >+
>>> > >+ uart at a000 {
>>> > >+ compatible = "fsl,imx-uart";
>>> > >+ reg = <0xa000 0x1000>;
>>> > >+ ...
>>> > >+ clocks = <&clkcon 0>, <&clkcon 3>;
>>> > >+ clock-names = "baud", "mux";
>>> > >+
>>> > >+ clock-parents = <0>, <&pll 1>;
>>> > >+ clock-rates = <460800>;
>>> > >+ };
>>> > >+
>>> > >+In this example the pll is set as parent of "mux" clock and frequency of "baud"
>>> > >+clock is specified as 460800 Hz.
[...]
>> >
>> > How do you support not-setting a rate for a clock?
>
> Not setting a rate is supported by specifying the rate to 0. That should
> be documented of course.
Yes, a rate won't be set for a clock if its corresponding entry in
clock-rates property is set to 0. Sorry, should have mentioned it.
Would adding a sentence as below to end of the first paragraph above
make it clear ?
"To skip setting a rate or parent for a clock the value of a corresponding
entry in the clock-rates or clock-parents property respectively should
be set to 0. The trailing zeros can be omitted."
--
Thanks,
Sylwester
next prev parent reply other threads:[~2014-04-01 9:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-31 16:41 [PATCH RFC v4 0/2] clk: Support for DT assigned clock parents and rates Sylwester Nawrocki
2014-03-31 16:41 ` [PATCH RFC v4 1/2] clk: Add function parsing arbitrary clock list DT property Sylwester Nawrocki
2014-03-31 16:41 ` [PATCH RFC v4 2/2] clk: Add handling of clk parent and rate assigned from DT Sylwester Nawrocki
2014-03-31 17:04 ` Ben Dooks
2014-04-01 6:23 ` Sascha Hauer
2014-04-01 9:31 ` Sylwester Nawrocki [this message]
2014-03-31 20:06 ` Greg KH
2014-04-01 13:19 ` Ben Dooks
2014-04-01 14:23 ` Sylwester Nawrocki
2014-04-01 16:37 ` Greg KH
2014-04-02 5:37 ` Sascha Hauer
2014-04-02 10:24 ` Sylwester Nawrocki
2014-04-02 10:18 ` Sylwester Nawrocki
2014-04-01 16:35 ` Greg KH
2014-04-02 8:01 ` Peter De Schrijver
2014-04-02 13:02 ` Sylwester Nawrocki
2014-04-01 13:15 ` Laurent Pinchart
2014-04-01 14:52 ` Sylwester Nawrocki
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