wait_for_completion_timeout can be called with timeout == 0 due to msecs_to_jiffies(2) == 1 for HZ < 1000 and usecs_to_jiffies(300) == 1 for all reasonable values of HZ, thus the following timeout /= 2; sets timeout to 0. This patch simply adds a lower-bounds of 1.

Signed-off-by: Nicholas Mc Guire hofrat@osadl.org ---

line numbers from wm9666.c linux-next -next-20150306

2101 /* Wait for the FLL to lock, using the interrupt if possible */ 2102 if (Fref > 1000000) 2103 timeout = usecs_to_jiffies(300); 2104 else 2105 timeout = msecs_to_jiffies(2); 2106 2107 /* Allow substantially longer if we've actually got the IRQ, poll 2108 * at a slightly higher rate if we don't. 2109 */ 2110 if (i2c->irq) 2111 timeout *= 10; 2112 else 2113 timeout /= 2; 2114 2115 ret = wait_for_completion_timeout(&wm8996->fll_lock, 2116 timeout);

The call-path here would then be: wait_for_completion_timeout(...,timeout) -> wait_for_common action==schedule_timeout -> schedule_timeout(timeout) ... expire = timeout + jiffies;

so expire == jiffies here and the timer would expire immediately for systems with HZ<1000 due to msecs_to_jiffies(2) == 1 and the following timeout /= 2 -> timeout == 0, which is probably a bit more that a "slightly higher rate".

This was only compile tested for exynos_defconfig + CONFIG_COMPILE_TEST=y, SND_SOC_ALL_CODECS=m (implies CONFIG_SND_SOC_WM8996=m)

Patch is against 4.0-rc2 linux-next (localversion-next is -next-20150306)

sound/soc/codecs/wm8996.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/wm8996.c b/sound/soc/codecs/wm8996.c index 24d9705..5ded102 100644 --- a/sound/soc/codecs/wm8996.c +++ b/sound/soc/codecs/wm8996.c @@ -2110,7 +2110,8 @@ static int wm8996_set_fll(struct snd_soc_codec *codec, int fll_id, int source, if (i2c->irq) timeout *= 10; else - timeout /= 2; + /* ensure timeout of atleast 1 jiffies */ + timeout = timeout/2 ? : 1;

for (retry = 0; retry < 10; retry++) { time_left = wait_for_completion_timeout(&wm8996->fll_lock,