From: Rob Herring <robherring2@gmail.com>
To: Richard Zhao <richard.zhao@freescale.com>
Cc: "Turquette, Mike" <mturquette@ti.com>,
andrew@lunn.ch, linaro-dev@lists.linaro.org,
eric.miao@linaro.org, grant.likely@secretlab.ca,
Colin Cross <ccross@google.com>,
jeremy.kerr@canonical.com, linux@arm.linux.org.uk,
sboyd@quicinc.com, magnus.damm@gmail.com, dsaxena@linaro.org,
linux-arm-kernel@lists.infradead.org, arnd.bergmann@linaro.org,
patches@linaro.org, Thomas Gleixner <tglx@linutronix.de>,
linux-omap@vger.kernel.org, richard.zhao@linaro.org,
shawn.guo@freescale.com, paul@pwsan.com,
linus.walleij@stericsson.com,
broonie@opensource.wolfsonmicro.com,
linux-kernel@vger.kernel.org, amit.kucheria@linaro.org,
skannan@quicinc.com
Subject: Re: [PATCH v4 3/6] clk: introduce the common clock framework
Date: Wed, 04 Jan 2012 08:32:31 -0600 [thread overview]
Message-ID: <4F0462FF.1000308@gmail.com> (raw)
In-Reply-To: <20120104021541.GI2414@b20223-02.ap.freescale.net>
On 01/03/2012 08:15 PM, Richard Zhao wrote:
> On Fri, Dec 16, 2011 at 04:45:48PM -0800, Turquette, Mike wrote:
>> On Wed, Dec 14, 2011 at 5:18 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
>>> On Tue, 13 Dec 2011, Mike Turquette wrote:
snip
>>>> +/**
>>>> + * clk_init - initialize the data structures in a struct clk
>>>> + * @dev: device initializing this clk, placeholder for now
>>>> + * @clk: clk being initialized
>>>> + *
>>>> + * Initializes the lists in struct clk, queries the hardware for the
>>>> + * parent and rate and sets them both. Adds the clk to the sysfs tree
>>>> + * topology.
>>>> + *
>>>> + * Caller must populate clk->name and clk->flags before calling
>>>
>>> I'm not too happy about this construct. That leaves struct clk and its
>>> members exposed to the world instead of making it a real opaque
>>> cookie. I know from my own painful experience, that this will lead to
>>> random fiddling in that data structure in drivers and arch code just
>>> because the core code has a shortcoming.
>>>
>>> Why can't we make struct clk a real cookie and confine the data
>>> structure to the core code ?
>>>
>>> That would change the init call to something like:
>>>
>>> struct clk *clk_init(struct device *dev, const struct clk_hw *hw,
>>> struct clk *parent)
>>>
>>> And have:
>>> struct clk_hw {
>>> struct clk_hw_ops *ops;
>>> const char *name;
>>> unsigned long flags;
>>> };
>>>
>>> Implementers can do:
>>> struct my_clk_hw {
>>> struct clk_hw hw;
>>> mydata;
>>> };
>>>
>>> And then change the clk ops callbacks to take struct clk_hw * as an
>>> argument.
> We have to define static clocks before we adopt DT binding.
> If clk is opaque and allocate memory in clk core, it'll make hard
> to define static clocks. And register/init will pass a long parameter
> list.
DT is not a prerequisite for having dynamically created clocks. You can
make clock init dynamic without DT.
What data goes in struct clk vs. struct clk_hw could change over time.
So perhaps we can start with some data in clk_hw and plan to move it to
struct clk later. Even if almost everything ends up in clk_hw initially,
at least the structure is in place to have common, core-only data
separate from platform data.
What is the actual data you need to be static and accessible to the
platform code? A ptr to parent clk is the main thing I've seen for
static initialization. So make the parent ptr be struct clk_hw* and
allow the platforms to access.
Rob
next prev parent reply other threads:[~2012-01-04 14:32 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-14 3:53 [PATCH v4 0/6] common clk framework Mike Turquette
2011-12-14 3:53 ` [PATCH v4 1/6] clk: Kconfig: add entry for HAVE_CLK_PREPARE Mike Turquette
2011-12-14 3:53 ` [PATCH v4 2/6] Documentation: common clk API Mike Turquette
2012-01-05 14:31 ` Amit Kucheria
2012-01-05 20:04 ` Turquette, Mike
2011-12-14 3:53 ` [PATCH v4 3/6] clk: introduce the common clock framework Mike Turquette
2011-12-14 4:52 ` Ryan Mallon
2011-12-14 19:07 ` Turquette, Mike
2011-12-14 7:50 ` Richard Zhao
2011-12-14 13:18 ` Thomas Gleixner
2011-12-17 0:45 ` Turquette, Mike
2011-12-17 11:04 ` Russell King - ARM Linux
2012-01-14 4:18 ` Saravana Kannan
2012-01-14 4:39 ` Turquette, Mike
2012-01-14 4:51 ` Saravana Kannan
2012-01-04 2:15 ` Richard Zhao
2012-01-04 14:32 ` Rob Herring [this message]
2012-01-05 1:01 ` Turquette, Mike
2012-01-05 1:23 ` Richard Zhao
2012-01-05 2:11 ` Rob Herring
2012-01-05 4:07 ` Turquette, Mike
2012-01-12 13:13 ` Amit Kucheria
2012-01-13 0:04 ` Saravana Kannan
2012-01-13 0:48 ` Rob Herring
2012-01-13 1:19 ` Saravana Kannan
2012-01-13 14:53 ` Shawn Guo
2011-12-14 3:53 ` [PATCH v4 4/6] clk: introduce rate change notifiers Mike Turquette
2011-12-14 3:53 ` [PATCH v4 5/6] clk: basic gateable and fixed-rate clks Mike Turquette
2011-12-14 5:15 ` Ryan Mallon
2011-12-17 0:57 ` Turquette, Mike
2011-12-14 3:53 ` [PATCH v4 6/6] clk: export the clk tree topology to debugfs Mike Turquette
2011-12-14 4:02 ` [PATCH v4 0/6] common clk framework Turquette, Mike
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