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media: mt9m114: Avoid a reset low spike during probe()

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mt9m114_probe() requests the reset GPIO in output low state:

	sensor->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);

and then almost immediately afterwards calls mt9m114_power_on() which does:

		gpiod_set_value(sensor->reset, 1);
		fsleep(duration);
		gpiod_set_value(sensor->reset, 0);

which means that if the reset pin was high before this code runs that
it will very briefly be driven low because of passing GPIOD_OUT_LOW when
requesting the GPIO only to be driven high again possibly directly after
that. Such a very brief driving low of the reset pin may put the chip in
a confused state.

Request the GPIO in high (reset the chip) state instead to avoid this,
turning the initial gpiod_set_value() in mt9m114_power_on() into a no-op.
and the fsleep() ensures that it will stay high long enough to properly
reset the chip.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
This commit is contained in:
Hans de Goede 2025-12-30 18:03:03 +01:00 committed by Hans Verkuil
parent 432d109333
commit 84359d0a5e
1 changed files with 1 additions and 1 deletions
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2
drivers/media/i2c/mt9m114.c
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@ -2467,7 +2467,7 @@ static int mt9m114_probe(struct i2c_client *client)
goto error_ep_free;
}
sensor->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
sensor->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
if (IS_ERR(sensor->reset)) {
ret = PTR_ERR(sensor->reset);
dev_err_probe(dev, ret, "Failed to get reset GPIO\n");