[PATCH 02/11] clk: Implement clk_set_rate
Stephen Boyd
sboyd at codeaurora.org
Tue Sep 13 15:03:28 EDT 2011
On 08/24/11 06:15, Mark Brown wrote:
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index ad90a90..3a4d70e 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -21,6 +21,8 @@ struct clk {
> unsigned int enable_count;
> unsigned int prepare_count;
> struct clk *parent;
> + struct hlist_head children;
> + struct hlist_node child_node;
Shouldn't these hlist nodes be initialized in clk_register() via
INIT_HLIST_*()? I guess it's not explicitly needed because kzalloc is
used, but perhaps it is better to be explicit should the kzalloc change
to a kmalloc.
> @@ -213,16 +266,25 @@ struct clk *clk_register(struct clk_hw_ops *ops, struct clk_hw *hw,
> clk->hw = hw;
> hw->clk = clk;
>
> - /* Query the hardware for parent and initial rate */
> + /* Query the hardware for parent and initial rate. We may alter
> + * the clock topology, making this clock available from the parent's
> + * children list. So, we need to protect against concurrent
> + * accesses through set_rate
> + */
> + mutex_lock(&prepare_lock);
>
> - if (clk->ops->get_parent)
> - /* We don't to lock against prepare/enable here, as
> - * the clock is not yet accessible from anywhere */
> + if (clk->ops->get_parent) {
> clk->parent = clk->ops->get_parent(clk->hw);
> + if (clk->parent)
> + hlist_add_head(&clk->child_node,
> + &clk->parent->children);
> + }
>
> if (clk->ops->recalc_rate)
> clk->rate = clk->ops->recalc_rate(clk->hw);
>
> + mutex_unlock(&prepare_lock);
> +
>
> return clk;
> }
--
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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