[PATCH V2] media: smiapp: core: add small range to usleep_range

From: Nicholas Mc Guire
Date: Wed May 08 2019 - 11:13:29 EST

No need for a high-accuracy delay here as long as it is more than 2
milliseconds this should be ok - as it is non-atomic context it will
be not be precise 2 milliseconds so giving the hrtimer subsystem 50
microseconds to merge timers and reduce interrupts.

Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxxxx>

Problem located by an experimental coccinelle script

V2: As Sakari Ailus <sakari.ailus@xxxxxx> noted that the delays would be
noticeable for the user but a range in the 50 microseconds range would
be acceptable - the range is reduced from 2 millisecond to 50 microseconds
which still gives the hrtimer subsystem some room for reducing interrupt

Patch was compile tested with: x86_64_defconfig + MEDIA_SUPPORT=m,

Patch is against 5.1 (localversion-next is next-20190508)

drivers/media/i2c/smiapp/smiapp-quirk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/i2c/smiapp/smiapp-quirk.c b/drivers/media/i2c/smiapp/smiapp-quirk.c
index 95c0272..59cb2a5 100644
--- a/drivers/media/i2c/smiapp/smiapp-quirk.c
+++ b/drivers/media/i2c/smiapp/smiapp-quirk.c
@@ -202,7 +202,7 @@ static int jt8ev1_post_streamoff(struct smiapp_sensor *sensor)
return rval;

/* Wait for 1 ms + one line => 2 ms is likely enough */
- usleep_range(2000, 2000);
+ usleep_range(2000, 2050);

/* Restore it */
rval = smiapp_write_8(sensor, 0x3205, 0x00);