Commit 69833527 authored by Hans de Goede's avatar Hans de Goede Committed by Hans Verkuil
Browse files

media: ov2740: Ensure proper reset sequence on probe() 



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: default avatarHans de Goede <hdegoede@redhat.com>
Tested-by: default avatarStanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Signed-off-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
parent 4ff61c4c

drivers/media/i2c/ov2740.c

+8 −1
Original line number Diff line number Diff line
@@ -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))