[PATCH v4 2/4] backlight: qcom-wled: Fix WLED3 brightness register stride

[David Heidelberg via B4 Relay <devnull+david.ixit.cz@kernel.org>]

From: David Heidelberg <david@ixit.cz>

WLED3 has a 16-bit brightness register pair per string, at 0x40 + 2*n,
which is what the pm8941-wled driver wrote to:

	rc = regmap_bulk_write(wled->regmap,
			wled->addr + WLED3_CTRL_REG_VAL_BASE + 2 * i,
			v, 2);

The restructuring for WLED3 turned that into WLED3_SINK_REG_BRIGHT(n),
defined as 0x40 + n, so the two byte writes for consecutive strings
overlap: string 1 overwrites the MSB of string 0 with its own LSB, and
with the default three strings only string 1 ends up with the requested
value.

Use the 2 byte stride.

Fixes: 775d2ffb4af6 ("backlight: qcom-wled: Restructure the driver for WLED3")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: David Heidelberg <david@ixit.cz>
---
 drivers/video/backlight/qcom-wled.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index 2281007bdd459..f452d328997ad 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -54,17 +54,17 @@
 #define WLED3_SINK_REG_SYNC				0x47
 #define  WLED3_SINK_REG_SYNC_CLEAR			0x00
 
 #define WLED3_SINK_REG_CURR_SINK			0x4f
 #define  WLED3_SINK_REG_CURR_SINK_MASK			GENMASK(7, 5)
 #define  WLED3_SINK_REG_CURR_SINK_SHFT			5
 
 /* WLED3 specific per-'string' registers below */
-#define WLED3_SINK_REG_BRIGHT(n)			(0x40 + n)
+#define WLED3_SINK_REG_BRIGHT(n)			(0x40 + (n * 0x2))
 
 #define WLED3_SINK_REG_STR_MOD_EN(n)			(0x60 + (n * 0x10))
 #define  WLED3_SINK_REG_STR_MOD_MASK			BIT(7)
 
 #define WLED3_SINK_REG_STR_FULL_SCALE_CURR(n)		(0x62 + (n * 0x10))
 #define  WLED3_SINK_REG_STR_FULL_SCALE_CURR_MASK	GENMASK(4, 0)
 
 #define WLED3_SINK_REG_STR_MOD_SRC(n)			(0x63 + (n * 0x10))

-- 
2.55.0