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Date: Wed, 3 Apr 2013 12:17:12 -0700
From: Soren Brinkmann <soren.brinkmann@...inx.com>
To: Mike Turquette <mturquette@...aro.org>,
Russell King <linux@....linux.org.uk>
CC: <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
Soren Brinkmann <soren.brinkmann@...inx.com>
Subject: [PATCH] clk: Properly handle notifier return values
Notifiers may return NOTIFY_(OK|DONE|STOP|BAD). The CCF uses an
inconsistent mix of checking against NOTIFY_STOP or NOTIFY_BAD.
This inconsistency leaves errors undetected in some cases:
clk_set_parent() calls __clk_speculate_rates(), which stops when it
hits a NOTIFIER_BAD (STOP is ignored), and passes this value back to the
caller.
clk_set_parent() compares this return value against NOTIFY_STOP only,
ignoring NOTIFY_BAD returns.
Use NOTIFY_STOP_MASK to detect a negative notifier return value and
document all four return value options.
Signed-off-by: Soren Brinkmann <soren.brinkmann@...inx.com>
---
drivers/clk/clk.c | 10 +++++-----
include/linux/clk.h | 8 ++++----
2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index ed87b24..68bd38c 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -876,16 +876,16 @@ static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
else
new_rate = parent_rate;
- /* abort the rate change if a driver returns NOTIFY_BAD */
+ /* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */
if (clk->notifier_count)
ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate);
- if (ret == NOTIFY_BAD)
+ if (ret & NOTIFY_STOP_MASK)
goto out;
hlist_for_each_entry(child, &clk->children, child_node) {
ret = __clk_speculate_rates(child, new_rate);
- if (ret == NOTIFY_BAD)
+ if (ret & NOTIFY_STOP_MASK)
break;
}
@@ -978,7 +978,7 @@ static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long even
if (clk->notifier_count) {
ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
- if (ret == NOTIFY_BAD)
+ if (ret & NOTIFY_STOP_MASK)
fail_clk = clk;
}
@@ -1296,7 +1296,7 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
ret = __clk_speculate_rates(clk, parent->rate);
/* abort if a driver objects */
- if (ret == NOTIFY_STOP)
+ if (ret & NOTIFY_STOP_MASK)
goto out;
/* only re-parent if the clock is not in use */
diff --git a/include/linux/clk.h b/include/linux/clk.h
index b3ac22d..9a6d045 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -28,16 +28,16 @@ struct clk;
* PRE_RATE_CHANGE - called immediately before the clk rate is changed,
* to indicate that the rate change will proceed. Drivers must
* immediately terminate any operations that will be affected by the
- * rate change. Callbacks may either return NOTIFY_DONE or
- * NOTIFY_STOP.
+ * rate change. Callbacks may either return NOTIFY_DONE, NOTIFY_OK,
+ * NOTIFY_STOP or NOTIFY_BAD.
*
* ABORT_RATE_CHANGE: called if the rate change failed for some reason
* after PRE_RATE_CHANGE. In this case, all registered notifiers on
* the clk will be called with ABORT_RATE_CHANGE. Callbacks must
- * always return NOTIFY_DONE.
+ * always return NOTIFY_DONE or NOTIFY_OK.
*
* POST_RATE_CHANGE - called after the clk rate change has successfully
- * completed. Callbacks must always return NOTIFY_DONE.
+ * completed. Callbacks must always return NOTIFY_DONE or NOTIFY_OK.
*
*/
#define PRE_RATE_CHANGE BIT(0)
--
1.8.2
--
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