[PATCH v3 4/9] leds: st1202: restore Pattern0 PWM to full on after clearing pattern

[Manuel Fombuena]

When PATS is cleared the LED output is the product of the ILED analog
current register and the Pattern0 PWM duty cycle. brightness_set only
writes the ILED register, so if Pattern0 PWM is zero the LED remains
dark regardless of the brightness value set.

pattern_clear zeros all pattern PWM registers including Pattern0, which
means any subsequent brightness_set call has no visible effect until a
new pattern is programmed.

Restore Pattern0 PWM to full duty cycle after clearing so that ILED
alone controls brightness in static mode.

Signed-off-by: Manuel Fombuena <fombuena@xxxxxxxxxxx>
Assisted-by: Claude:claude-sonnet-4-6
---
 drivers/leds/leds-st1202.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/leds-st1202.c b/drivers/leds/leds-st1202.c
index b4adade49898..b32d8e716372 100644
--- a/drivers/leds/leds-st1202.c
+++ b/drivers/leds/leds-st1202.c
@@ -35,6 +35,7 @@
 #define ST1202_MILLIS_PATTERN_DUR_MIN      22
 #define ST1202_PATTERN_DUR                 0x16
 #define ST1202_PATTERN_PWM                 0x1E
+#define ST1202_PATTERN_PWM_FULL            0x0FFF
 #define ST1202_PATTERN_REP                 0x15
 
 struct st1202_led {
@@ -204,7 +205,15 @@ static int st1202_led_pattern_clear(struct led_classdev *ldev)
 	if (ret != 0)
 		return ret;
 
-	for (int patt = 0; patt < ST1202_MAX_PATTERNS; patt++) {
+	ret = st1202_pwm_pattern_write(chip, led->led_num, 0, ST1202_PATTERN_PWM_FULL);
+	if (ret != 0)
+		return ret;
+
+	ret = st1202_write_reg(chip, ST1202_PATTERN_DUR, 0);
+	if (ret != 0)
+		return ret;
+
+	for (int patt = 1; patt < ST1202_MAX_PATTERNS; patt++) {
 		ret = st1202_pwm_pattern_write(chip, led->led_num, patt, LED_OFF);
 		if (ret != 0)
 			return ret;
-- 
2.54.0