On Sat Mar 1 12:48:29 2025 +0100, Hans de Goede wrote:
> We should put/leave the sensor in reset when requesting the GPIO, after
> requesting it there are 2 possible scenarios and having the GPIO driven
> low is no good in either scenario:
>
> 1. The sensor was in ACPI D0 before probe() runs, in this case
> ov08x40_power_on() + ov08x40_identify_module() will run immediately
> after requesting the GPIO and ov08x40_power_on() starts with driving
> the GPIO high. So if the GPIO was already high it will very shortly
> be driven low, more of a spike to low then actually properly be driven
> low. Which may leave the sensor in a confused state.
>
> If we request the GPIO to be high at request time then power_on() will
> driver it high again (no-op) and then sleep for 1-2 ms, so no spike.
>
> 2. The sensor was in ACPI D3 / off before probe(), in this case probe()
> leaves the sensor alone. But when the sensor is off its reset line
> should be driven high not low.
>
> Signed-off-by: Hans de Goede <hdego...@redhat.com>
> Reviewed-by: Bryan O'Donoghue <bryan.odonog...@linaro.org>
> Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
> Signed-off-by: Hans Verkuil <hverk...@xs4all.nl>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/i2c/ov08x40.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/drivers/media/i2c/ov08x40.c b/drivers/media/i2c/ov08x40.c
index c2a399e3bb41..a4790e68f523 100644
--- a/drivers/media/i2c/ov08x40.c
+++ b/drivers/media/i2c/ov08x40.c
@@ -2167,7 +2167,7 @@ static int ov08x40_check_hwcfg(struct ov08x40 *ov08x,
struct device *dev)
return dev_err_probe(dev, ret, "parsing endpoint failed\n");
ov08x->reset_gpio = devm_gpiod_get_optional(dev, "reset",
- GPIOD_OUT_LOW);
+ GPIOD_OUT_HIGH);
if (IS_ERR(ov08x->reset_gpio)) {
ret = dev_err_probe(dev, PTR_ERR(ov08x->reset_gpio),
"getting reset GPIO\n");
