diff options
| author | Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com> | 2025-12-30 09:34:36 +0100 |
|---|---|---|
| committer | Hans Verkuil <hverkuil+cisco@kernel.org> | 2026-01-16 14:08:52 +0100 |
| commit | 5152437f7610eb522fd233ab548a19d4601cbc2a (patch) | |
| tree | 23cc440773006ed1982c4b678ab062d3068f0427 | |
| parent | 2f130245f2143fa8f4da77071f844911d2c69319 (diff) | |
| download | linux-5152437f7610eb522fd233ab548a19d4601cbc2a.tar.gz linux-5152437f7610eb522fd233ab548a19d4601cbc2a.zip | |
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 <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
| -rw-r--r-- | drivers/media/i2c/adv7604.c | 8 | ||||
| -rw-r--r-- | drivers/media/i2c/et8ek8/et8ek8_driver.c | 4 |
2 files changed, 11 insertions, 1 deletions
diff --git a/drivers/media/i2c/adv7604.c b/drivers/media/i2c/adv7604.c index 516553fb17e9..67116a4ef134 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 2cb7b718782b..50121c3e5b48 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 */ |