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