From: Grant Likely <grant.likely@secretlab.ca>
To: Rob Herring <robherring2@gmail.com>
Cc: Jamie Iles <jamie@jamieiles.com>,
linux-kernel@vger.kernel.org,
devicetree-discuss@lists.ozlabs.org,
Sascha Hauer <kernel@pengutronix.de>,
Mike Turquette <mturquette@ti.com>
Subject: Re: [RFC v2 4/9] of: add clock providers
Date: Tue, 13 Dec 2011 11:03:57 -0700 [thread overview]
Message-ID: <CACxGe6sh+ofJWSA8xpDazEKVOUOpaHK45Qm8C20zpyRaLT77Mg@mail.gmail.com> (raw)
In-Reply-To: <4EE792DF.1010701@gmail.com>
On Tue, Dec 13, 2011 at 11:01 AM, Rob Herring <robherring2@gmail.com> wrote:
> Grant,
>
> On 12/13/2011 11:54 AM, Grant Likely wrote:
>> On Mon, Dec 12, 2011 at 4:29 PM, Jamie Iles <jamie@jamieiles.com> wrote:
>>> Hi Grant,
>>>
>>> I'm still going through these and trying to digest them but a couple of
>>> quick questions/comments.
>>>
>>> Jamie
>>>
>>> On Mon, Dec 12, 2011 at 03:02:04PM -0700, Grant Likely wrote:
>>>> diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt
>>>> new file mode 100644
>>>> index 0000000..e40c436
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt
>>>> @@ -0,0 +1,114 @@
>>>> +This binding is a work-in-progress, and are based on some experimental
>>>> +work by benh[1].
>>>> +
>>>> +Sources of clock signal can be represented by any node in the device
>>>> +tree. Those nodes are designated as clock providers. Clock consumer
>>>> +nodes use a phandle and clock specifier pair to connect clock provider
>>>> +outputs to clock inputs. Similar to the gpio specifiers, a clock
>>>> +specifier is an array of one more more cells identifying the clock
>>>> +output on a device. The length of a clock specifier is defined by the
>>>> +value of a #clock-cells property in the clock provider node.
>>>> +
>>>> +[1] http://patchwork.ozlabs.org/patch/31551/
>>>> +
>>>> +==Clock providers==
>>>> +
>>>> +Required properties:
>>>> +#clock-cells: Number of cells in a clock specifier; typically will be
>>>> + set to 1
>>>
>>> I'm not sure I fully understand what the extra cells actually mean for
>>> clocks. I think the first integer is the clock output to use but some
>>> of the versatile and highbank ones only have a phandle or is it more
>>> implementation defined? The clock-output-names description hints at
>>> recommended, so I find this a little confusing, but that could just be
>>> me!
>>
>> I'm following convention here that has been established with
>> interrupts, gpios, and others. Sometimes more information is needed
>> that just the clock number. Using #clock-cells gives a clock provider
>> the option of having additional fields for clock flags or other data.
>> This is very much implementation defined. Simple clock providers that
>> only have a single clock output can easily use #clock-cells = <0>.
>> Providers with multiple outputs will need to use 1 or more cells.
>>
>
> Aren't you off by 1 here? The minimum cells is 1 to hold the phandle of
> the source/parent. Multiple outputs will need a cell size of 2 (typically).
No. The #clock-cells does not include the phandle. Never did.
g.
next prev parent reply other threads:[~2011-12-13 18:04 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-12 22:02 [RFC v2 1/9] arm/versatile*: merge all versatile struct clk definitions Grant Likely
2011-12-12 22:02 ` [RFC v2 2/9] arm/versatile*: Consolidate clk_ops and setvco implementations Grant Likely
2011-12-12 22:02 ` [RFC v2 3/9] of: Add of_property_match_string() to find index into a string list Grant Likely
2011-12-12 22:02 ` [RFC v2 4/9] of: add clock providers Grant Likely
2011-12-12 23:29 ` Jamie Iles
2011-12-13 17:54 ` Grant Likely
2011-12-13 18:01 ` Rob Herring
2011-12-13 18:03 ` Grant Likely [this message]
2011-12-15 13:51 ` Shawn Guo
2011-12-15 14:23 ` Rob Herring
2011-12-15 15:13 ` Shawn Guo
2011-12-15 17:37 ` Grant Likely
2012-01-10 21:33 ` Jamie Iles
2012-01-12 4:46 ` Grant Likely
2012-01-12 10:07 ` Jamie Iles
2012-01-12 18:44 ` Turquette, Mike
2012-01-12 19:16 ` Grant Likely
2012-01-13 12:47 ` Shawn Guo
2012-01-14 4:30 ` Turquette, Mike
2012-01-14 5:40 ` Shawn Guo
2012-01-13 13:50 ` Shawn Guo
2012-01-13 14:05 ` Rob Herring
2012-01-13 14:38 ` Shawn Guo
2012-01-17 20:44 ` Stephen Warren
2012-01-17 22:47 ` Grant Likely
2012-01-17 23:37 ` Turquette, Mike
2012-01-17 23:49 ` Grant Likely
2012-01-18 0:05 ` Stephen Warren
2011-12-12 22:02 ` [RFC v2 5/9] dt/clock: Add handling for fixed clocks and a clock node setup iterator Grant Likely
2011-12-15 15:19 ` Shawn Guo
2011-12-12 22:02 ` [RFC v2 6/9] arm/dt: add devicetree support to sp804 timer support Grant Likely
2011-12-12 23:54 ` Rob Herring
2011-12-12 22:02 ` [RFC v2 7/9] arm/dt: Common plat-versatile support for icst and sp804 based system clocks Grant Likely
2012-01-17 21:05 ` Stephen Warren
2012-01-17 22:02 ` Rob Herring
2012-01-17 22:59 ` Grant Likely
2011-12-12 22:02 ` [RFC v2 8/9] dt/arm: versatile add clock parsing Grant Likely
2011-12-12 22:02 ` [RFC v2 9/9] arm/highbank: Use clock binding common support code Grant Likely
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