media: hi556: Fix reset GPIO timings

probe() requests the reset GPIO to be set to high when getting it.
Immeditately after this hi556_resume() is called and sets the GPIO low.

If the GPIO was low before requesting it this will result in the GPIO
only very briefly spiking high and the sensor not being properly reset.
The same problem also happens on back to back runtime suspend + resume.

Fix this by adding a sleep of 2 ms in hi556_resume() before setting
the GPIO low (if there is a reset GPIO).

The final sleep is kept unconditional, because if there is e.g. no reset
GPIO but a controllable clock then the sensor also needs some time after
enabling the clock.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

diff --git a/drivers/media/i2c/hi556.c b/drivers/media/i2c/hi556.c
index aed258211b8a88b257040164b18f3eacb4d026cd..d3cc65b67855c8abe6034614da6fabfe8265e722 100644 (file)
--- a/drivers/media/i2c/hi556.c
+++ b/drivers/media/i2c/hi556.c
@@ -1321,7 +1321,12 @@ static int hi556_resume(struct device *dev)
                return ret;
        }
 
-       gpiod_set_value_cansleep(hi556->reset_gpio, 0);
+       if (hi556->reset_gpio) {
+               /* Assert reset for at least 2ms on back to back off-on */
+               usleep_range(2000, 2200);
+               gpiod_set_value_cansleep(hi556->reset_gpio, 0);
+       }
+
        usleep_range(5000, 5500);
        return 0;
 }