On Mon, May 06, 2024 at 03:24:38PM +0200, Hans de Goede wrote:
> 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 <hdegoede@xxxxxxxxxx>
Tested-by: Stanislaw Gruszka <stanislaw.gruszka@xxxxxxxxxxxxxxx>
This fixes this issue:
[ 7.742633] ov2740 i2c-INT3474:01: chip id mismatch: 2740 != 0
[ 7.742638] ov2740 i2c-INT3474:01: error -ENXIO: failed to find sensor
for me as well.
Thanks!
Stanislaw
> ---
> 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))
> --
> 2.44.0
>
