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drivers/touch/cst816: take the i2c lock around the hardware reset #1896

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Mearman wants to merge 1 commit into from
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drivers/touch/cst816: take the i2c lock around the hardware reset #1896

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3 changes: 3 additions & 0 deletions src/fw/drivers/touch/cst816/cst816.c
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Original file line number Diff line number Diff line change
Expand Up @@ -223,6 +223,8 @@ static bool cst816_fw_update(void) {
}

static void cst816_hw_reset(void) {
// Toggling the reset pin must not race an in-flight I2C transfer on another task: a chip hit by reset mid-byte stops ACKing and corrupts the transfer (touch_sensor_set_enabled is reachable synchronously from arbitrary tasks while the system task services IRQ-driven reads). Take the same per-transfer lock prv_read_data/prv_write_data use. No caller holds it already -- the only lock-takers are those two, neither of which resets -- so this cannot self-deadlock.

@gmarull gmarull Aug 24, 2026

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change makes sense, could all this verbose comment be removed, details kept in the commit?

mutex_lock(s_i2c_lock);
#ifdef RESET_PIN_CTRLBY_NPM1300
NPM1300_OPS.gpio_set(Npm1300_Gpio2, 0);
psleep(CST816_RESET_CYCLE_TIME);
Expand All @@ -234,6 +236,7 @@ static void cst816_hw_reset(void) {
gpio_output_set(&CST816->reset, false);
psleep(CST816_POR_DELAY_TIME);
#endif
mutex_unlock(s_i2c_lock);
}

void touch_sensor_init(void) {
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