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Subject: media: ov2740: Ensure proper reset sequence on probe()
Author: Hans de Goede <hdego...@redhat.com>
Date: Mon May 6 15:24:38 2024 +0200
Before this commit on probe() the driver would do:
reset=1 // from probe() calling gpiod_get(GPIOD_OUT_HIGH)
reset=0 // from resume()
msleep(20) // from resume()
So if reset was 0 before getting the GPIO the reset line would only be
driven high for a very short time and sometimes there would be errors
reading the id register afterwards.
Add a msleep(20) after getting the reset line to ensure the sensor is
properly reset:
reset=1 // from probe() calling gpiod_get(GPIOD_OUT_HIGH)
msleep(20) // from probe()
reset=0 // from resume()
msleep(20) // from resume()
Signed-off-by: Hans de Goede <hdego...@redhat.com>
Tested-by: Stanislaw Gruszka <stanislaw.grus...@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-ci...@xs4all.nl>
drivers/media/i2c/ov2740.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
---
diff --git a/drivers/media/i2c/ov2740.c b/drivers/media/i2c/ov2740.c
index 57906df7be4e..c48dbcde9877 100644
--- a/drivers/media/i2c/ov2740.c
+++ b/drivers/media/i2c/ov2740.c
@@ -1333,9 +1333,16 @@ static int ov2740_probe(struct i2c_client *client)
return dev_err_probe(dev, ret, "failed to check HW
configuration\n");
ov2740->reset_gpio = devm_gpiod_get_optional(dev, "reset",
GPIOD_OUT_HIGH);
- if (IS_ERR(ov2740->reset_gpio))
+ if (IS_ERR(ov2740->reset_gpio)) {
return dev_err_probe(dev, PTR_ERR(ov2740->reset_gpio),
"failed to get reset GPIO\n");
+ } else if (ov2740->reset_gpio) {
+ /*
+ * Ensure reset is asserted for at least 20 ms before
+ * ov2740_resume() deasserts it.
+ */
+ msleep(20);
+ }
ov2740->clk = devm_clk_get_optional(dev, "clk");
if (IS_ERR(ov2740->clk))
