Messages in this thread | | | Date | Wed, 04 Jan 2012 08:32:31 -0600 | From | Rob Herring <> | Subject | Re: [PATCH v4 3/6] clk: introduce the common clock framework |
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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
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