On Thu, May 03, 2012 at 06:11:56PM -0700, Saravana Kannan wrote:

On 05/03/2012 04:03 PM, Domenico Andreoli wrote:

quoted

On Wed, Apr 25, 2012 at 10:58:56PM -0700, Saravana Kannan wrote:

quoted

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index 90627e4..8ea11b4 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c

@@ -167,6 +167,7 @@ struct clk *clk_register_divider(struct device *dev, const char *name,
 {
 	struct clk_divider *div;
 	struct clk *clk;
+	struct clk_init_data init;

 	/* allocate the divider */
 	div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);

@@ -175,19 +176,22 @@ struct clk *clk_register_divider(struct device *dev, const char *name,
 		return ERR_PTR(-ENOMEM);
 	}

+	init.name = name;
+	init.ops =&clk_divider_ops;
+	init.flags = flags;
+	init.parent_names = (parent_name ?&parent_name: NULL);
+	init.num_parents = (parent_name ? 1 : 0);
+
 	/* struct clk_divider assignments */
 	div->reg = reg;
 	div->shift = shift;
 	div->width = width;
 	div->flags = clk_divider_flags;
 	div->lock = lock;
+	div->hw.init =&init;

 	/* register the clock */
-	clk = clk_register(dev, name,
-			&clk_divider_ops,&div->hw,
-			(parent_name ?&parent_name: NULL),
-			(parent_name ? 1 : 0),
-			flags);
+	clk = clk_register(dev,&div->hw);

 	if (IS_ERR(clk))
 		kfree(div);

I would prefer to rip the parent _settings_ configuration out of
clk_register(). It's optional right? And passing a single parent is a
common case.

Three cases:

  1) one parent:
     __clk_register_parent(clk, parent_name);
     clk_register(dev, name,&ops, flags);

  2) many parents:
     __clk_register_parents(clk, parent_names, num_parents);
     clk_register(dev, name,&ops, flags);

  3) no parents:
     clk_register(dev, name,&ops, flags);

You may also want to move the whole parent initialization into
__clk_register_parents() and call it after clk_register(), it would
simplify some error paths.

This pattern could be used also with other common clocks registration
functions (fixed rate, divider, mux, etc) that may have complex
initializations and/or optional parameters that cannot go all on the
same function call.

Please no. If anything, make those other register functions go in
the direction of clk_register(). Have a long list of params to a
function and then having it fill up a structure just makes the code
less readable. Why would that be any better than having the whole
structure statically declared or the whole structure dynamically
populated (by device tree) and then calling clk_register()?

Take about 50 clocks with 3 parents each and try to register them in
the way you suggested and in a way how clk_register() in this patch
will need you to declare them statically. Compare the two and see
which would be more readable.

I was not thinking at the static initialization at all (but I was
forgetting that clk does not yet exist before the invocation of
clk_register).

For a few hours I was convinced that moving the parent initialization
stuff in a separate function would have allowed also to ditch the (IMHO)
horrible whole name caching (whose purpose is... allowing to register
clock with a parent not yet known to the clock subsystem?)

Unfortunately the whole idea is quite invasive and the benefits
debatable, it's simply too late to speak.

Thanks anyway.

Domenico