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Subject[PATCH 2/2] ASoC: wm8996: ensure lower bounds of 1 for timeout
Date
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,
--
1.7.10.4


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