[PATCH v2 01/10] leds: st1202: stop pattern sequence before reprogramming

[Manuel Fombuena]

The LED1202 datasheet (section 4.8) states that modifications to the
Pattern Sequence Repetition register (PAT_REP) and pattern duration
registers are only applied after the sequence has completed or been
stopped. When the device is running in infinite loop mode (PAT_REP =
0xFF) the sequence never completes on its own, so these writes are
silently ignored by the hardware.

Neither pattern_clear() nor pattern_set() stop the running sequence
before modifying pattern registers, causing any subsequent pattern
reprogramming to have no effect when the previous pattern was set to
infinite repeat.

Fix this by clearing PATS in the Configuration register before touching
any pattern registers in both functions, ensuring the hardware accepts
the new values immediately.

Fixes: 259230378c65 ("leds: Add LED1202 I2C driver")
Signed-off-by: Manuel Fombuena <fombuena@xxxxxxxxxxx>
Assisted-by: Claude:claude-sonnet-4-6
---
 drivers/leds/leds-st1202.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/leds/leds-st1202.c b/drivers/leds/leds-st1202.c
index 2b68cd3c45f8..28e3f1e2314c 100644
--- a/drivers/leds/leds-st1202.c
+++ b/drivers/leds/leds-st1202.c
@@ -200,6 +200,10 @@ static int st1202_led_pattern_clear(struct led_classdev *ldev)
 
 	guard(mutex)(&chip->lock);
 
+	ret = st1202_write_reg(chip, ST1202_CONFIG_REG, ST1202_CONFIG_REG_SHFT);
+	if (ret != 0)
+		return ret;
+
 	for (int patt = 0; patt < ST1202_MAX_PATTERNS; patt++) {
 		ret = st1202_pwm_pattern_write(chip, led->led_num, patt, LED_OFF);
 		if (ret != 0)
@@ -226,6 +230,10 @@ static int st1202_led_pattern_set(struct led_classdev *ldev,
 
 	guard(mutex)(&chip->lock);
 
+	ret = st1202_write_reg(chip, ST1202_CONFIG_REG, ST1202_CONFIG_REG_SHFT);
+	if (ret != 0)
+		return ret;
+
 	for (int patt = 0; patt < len; patt++) {
 		if (pattern[patt].delta_t < ST1202_MILLIS_PATTERN_DUR_MIN ||
 				pattern[patt].delta_t > ST1202_MILLIS_PATTERN_DUR_MAX)
-- 
2.54.0