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boards/esp32s3: the LSM6DS3TR-C INT1 is a level, not an edge

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The FIFO watermark flag is a level: it stays high until the worker
actually drains the FIFO below the threshold.  Configuring INT1 as RISING
made that a race the driver could lose permanently.

lsm6ds3trc_interrupt() disables its IRQ on entry and re-enables it after
the worker has run.  With an edge trigger, if the line is still high when
the IRQ is re-enabled -- which is precisely what happens whenever a drain
does not take the FIFO below the watermark -- there is no new low-to-high
transition left to detect, and the line goes mute forever.  Observed as a
board that serviced exactly one watermark after boot and then never
again, reproducible 2 out of 2 reflashes.

ONHIGH matches the physical meaning of the pin and is immune to it: a
level trigger re-asserts on its own for as long as the condition holds,
and the disable/enable pairing around servicing is what stops that from
live-locking.

Validated with more than 900 consecutive drains (~100 min) including real
sleep -> GPIO-wake -> resume transitions, the exact case that used to
wedge.

Signed-off-by: Felipe Moura <moura.fmo@gmail.com>
Assisted-by: Claude:claude-opus-5
This commit is contained in:
Felipe Moura 2026-09-19 17:57:47 -03:00 • committed by Alan C. Assis
parent b120999159
commit e4cc7b7258
1 changed files with 5 additions and 5 deletions
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10
boards/xtensa/esp32s3/common/src/esp32s3_board_lsm6ds3trc.c
View file

@ -110,13 +110,13 @@ int board_lsm6ds3trc_initialize(int devno, int busno)
.attach = board_lsm6ds3trc_attach,
};
/* The IMU drives INT1 push-pull, active high by default (CTRL3_C
* H_LACTIVE reset value) -- rising edge signals data ready. No pull
* needed once the sensor drives the line, but PULLDOWN gives a defined
* idle state before CTRL registers are written during registration.
/* INT1 is a level (FIFO over watermark), not a pulse -- ONHIGH, not
* RISING, or the disable/re-enable around servicing can miss the line
* already back high and never fire again. PULLDOWN just gives a defined
* idle state before CTRL registers are written.
*/
esp_configgpio(LSM6DS3TRC_IRQ_PIN, INPUT_FUNCTION_2 | PULLDOWN | RISING);
esp_configgpio(LSM6DS3TRC_IRQ_PIN, INPUT_FUNCTION_2 | PULLDOWN | ONHIGH);
i2c = esp32s3_i2cbus_initialize(busno);
if (i2c == NULL)