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clk: Properly handle notifier return values

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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@xilinx.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
This commit is contained in:
Soren Brinkmann 2013-04-03 12:17:12 -07:00 committed by Mike Turquette
parent 312f0f0b9a
commit fb72a0590b
2 changed files with 9 additions and 9 deletions
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10
drivers/clk/clk.c
View File

@ -1027,16 +1027,16 @@ static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
else else
new_rate = parent_rate; 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) if (clk->notifier_count)
ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate); ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate);
if (ret == NOTIFY_BAD) if (ret & NOTIFY_STOP_MASK)
goto out; goto out;
hlist_for_each_entry(child, &clk->children, child_node) { hlist_for_each_entry(child, &clk->children, child_node) {
ret = __clk_speculate_rates(child, new_rate); ret = __clk_speculate_rates(child, new_rate);
if (ret == NOTIFY_BAD) if (ret & NOTIFY_STOP_MASK)
break; break;
} }
@ -1129,7 +1129,7 @@ static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long even
if (clk->notifier_count) { if (clk->notifier_count) {
ret = __clk_notify(clk, event, clk->rate, clk->new_rate); ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
if (ret == NOTIFY_BAD) if (ret & NOTIFY_STOP_MASK)
fail_clk = clk; fail_clk = clk;
} }
@ -1484,7 +1484,7 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
ret = __clk_speculate_rates(clk, p_rate); ret = __clk_speculate_rates(clk, p_rate);
/* abort if a driver objects */ /* abort if a driver objects */
if (ret == NOTIFY_STOP) if (ret & NOTIFY_STOP_MASK)
goto out; goto out;
/* do the re-parent */ /* do the re-parent */

8
include/linux/clk.h
View File

@ -28,16 +28,16 @@ struct clk;
* PRE_RATE_CHANGE - called immediately before the clk rate is changed, * PRE_RATE_CHANGE - called immediately before the clk rate is changed,
* to indicate that the rate change will proceed. Drivers must * to indicate that the rate change will proceed. Drivers must
* immediately terminate any operations that will be affected by the * immediately terminate any operations that will be affected by the
* rate change. Callbacks may either return NOTIFY_DONE or * rate change. Callbacks may either return NOTIFY_DONE, NOTIFY_OK,
* NOTIFY_STOP. * NOTIFY_STOP or NOTIFY_BAD.
* *
* ABORT_RATE_CHANGE: called if the rate change failed for some reason * ABORT_RATE_CHANGE: called if the rate change failed for some reason
* after PRE_RATE_CHANGE. In this case, all registered notifiers on * after PRE_RATE_CHANGE. In this case, all registered notifiers on
* the clk will be called with ABORT_RATE_CHANGE. Callbacks must * 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 * 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) #define PRE_RATE_CHANGE BIT(0)