From 5152437f7610eb522fd233ab548a19d4601cbc2a Mon Sep 17 00:00:00 2001 From: Krzysztof Kozlowski Date: Tue, 30 Dec 2025 09:34:36 +0100 Subject: [PATCH] media: i2c: Add note to prevent buggy code re-use adv7604 and et8ek8 sensor drivers have mixed up logical and line level for reset/powerdown signal. They call it a reset signal (it indeed behaves like that), but drivers assert the reset to operate which is clearly incorrect and relies on wrong ACTIVE_HIGH flag in the DTS. People in discussions copy existing poor code and claim they can repeat same mistake, so add a note to prevent that. Signed-off-by: Krzysztof Kozlowski Signed-off-by: Sakari Ailus Signed-off-by: Hans Verkuil --- drivers/media/i2c/adv7604.c | 8 +++++++- drivers/media/i2c/et8ek8/et8ek8_driver.c | 4 ++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/media/i2c/adv7604.c b/drivers/media/i2c/adv7604.c index 516553fb17e98..67116a4ef134e 100644 --- a/drivers/media/i2c/adv7604.c +++ b/drivers/media/i2c/adv7604.c @@ -3453,7 +3453,13 @@ static int configure_regmaps(struct adv76xx_state *state) static void adv76xx_reset(struct adv76xx_state *state) { if (state->reset_gpio) { - /* ADV76XX can be reset by a low reset pulse of minimum 5 ms. */ + /* + * Note: Misinterpretation of reset assertion - do not re-use + * this code. The reset pin is using incorrect (for a reset + * signal) logical level. + * + * ADV76XX can be reset by a low reset pulse of minimum 5 ms. + */ gpiod_set_value_cansleep(state->reset_gpio, 0); usleep_range(5000, 10000); gpiod_set_value_cansleep(state->reset_gpio, 1); diff --git a/drivers/media/i2c/et8ek8/et8ek8_driver.c b/drivers/media/i2c/et8ek8/et8ek8_driver.c index 2cb7b718782b2..50121c3e5b480 100644 --- a/drivers/media/i2c/et8ek8/et8ek8_driver.c +++ b/drivers/media/i2c/et8ek8/et8ek8_driver.c @@ -835,6 +835,10 @@ static int et8ek8_power_on(struct et8ek8_sensor *sensor) udelay(10); /* I wish this is a good value */ + /* + * Note: Misinterpretation of reset assertion - do not re-use this code. + * The reset pin is using incorrect (for a reset signal) logical level. + */ gpiod_set_value(sensor->reset, 1); msleep(5000 * 1000 / sensor->xclk_freq + 1); /* Wait 5000 cycles */ -- 2.47.3