From 86bcfa2e87c42b8af77188e7a939e952199d4da1 Mon Sep 17 00:00:00 2001 From: Mike Turquette Date: Mon, 24 Feb 2014 16:08:41 -0800 Subject: clk: add pr_debug & kerneldoc around clk notifiers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Both the pr_err and the additional kerneldoc aim to help when debugging errors thrown from within a clock rate-change notifier callback. Reported-by: Sören Brinkmann Acked-by: Sören Brinkmann Signed-off-by: Mike Turquette --- drivers/clk/clk.c | 5 ++++- include/linux/clk.h | 14 ++++++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index a6f079d23ea..f30e6af9033 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1339,8 +1339,11 @@ static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate) if (clk->notifier_count) ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate); - if (ret & NOTIFY_STOP_MASK) + if (ret & NOTIFY_STOP_MASK) { + pr_debug("%s: clk notifier callback for clock %s aborted with error %d\n", + __func__, clk->name, ret); goto out; + } hlist_for_each_entry(child, &clk->children, child_node) { ret = __clk_speculate_rates(child, new_rate); diff --git a/include/linux/clk.h b/include/linux/clk.h index 0dd91148165..fb5e097d8f7 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -78,8 +78,22 @@ struct clk_notifier_data { unsigned long new_rate; }; +/** + * clk_notifier_register: register a clock rate-change notifier callback + * @clk: clock whose rate we are interested in + * @nb: notifier block with callback function pointer + * + * ProTip: debugging across notifier chains can be frustrating. Make sure that + * your notifier callback function prints a nice big warning in case of + * failure. + */ int clk_notifier_register(struct clk *clk, struct notifier_block *nb); +/** + * clk_notifier_unregister: unregister a clock rate-change notifier callback + * @clk: clock whose rate we are no longer interested in + * @nb: notifier block which will be unregistered + */ int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb); /** -- cgit v1.2.3-70-g09d2