]> git.ipfire.org Git - thirdparty/kernel/linux.git/commit
media: mt9m114: Avoid a reset low spike during probe()
authorHans de Goede <johannes.goede@oss.qualcomm.com>
Tue, 30 Dec 2025 17:03:03 +0000 (18:03 +0100)
committerHans Verkuil <hverkuil+cisco@kernel.org>
Wed, 14 Jan 2026 22:33:04 +0000 (23:33 +0100)
commit84359d0a5e3afce5e3e3b6562efadff690614d5b
treefe574ad9483b64ba829ab9ba5629d0f955e34795
parent432d109333afd674a416a061b98264bfcd5f0515
media: mt9m114: Avoid a reset low spike during probe()

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>
drivers/media/i2c/mt9m114.c