[PATCH V4 1/2] backlight: qcom-wled: Fix FSC update issue for WLED5

[PATCH V4 1/2] backlight: qcom-wled: Fix FSC update issue for WLED5

[Kiran Gunda]

Currently, for WLED5, the FSC (Full scale current) setting is not
updated properly due to driver toggling the wrong register after
an FSC update.

On WLED5 we should only toggle the MOD_SYNC bit after a brightness
update. For an FSC update we need to toggle the SYNC bits instead.

Fix it by adopting the common wled3_sync_toggle() for WLED5 and
introducing new code to the brightness update path to compensate.

Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
---
 drivers/video/backlight/qcom-wled.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index 3bc7800..aef52b9 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -348,7 +348,7 @@ static int wled3_sync_toggle(struct wled *wled)
 	return rc;
 }
 
-static int wled5_sync_toggle(struct wled *wled)
+static int wled5_mod_sync_toggle(struct wled *wled)
 {
 	int rc;
 	u8 val;
@@ -445,10 +445,23 @@ static int wled_update_status(struct backlight_device *bl)
 			goto unlock_mutex;
 		}
 
-		rc = wled->wled_sync_toggle(wled);
-		if (rc < 0) {
-			dev_err(wled->dev, "wled sync failed rc:%d\n", rc);
-			goto unlock_mutex;
+		if (wled->version < 5) {
+			rc = wled->wled_sync_toggle(wled);
+			if (rc < 0) {
+				dev_err(wled->dev, "wled sync failed rc:%d\n", rc);
+				goto unlock_mutex;
+			}
+		} else {
+			/*
+			 * For WLED5 toggling the MOD_SYNC_BIT updates the
+			 * brightness
+			 */
+			rc = wled5_mod_sync_toggle(wled);
+			if (rc < 0) {
+				dev_err(wled->dev, "wled mod sync failed rc:%d\n",
+					rc);
+				goto unlock_mutex;
+			}
 		}
 	}
 
@@ -1459,7 +1472,7 @@ static int wled_configure(struct wled *wled)
 		size = ARRAY_SIZE(wled5_opts);
 		*cfg = wled5_config_defaults;
 		wled->wled_set_brightness = wled5_set_brightness;
-		wled->wled_sync_toggle = wled5_sync_toggle;
+		wled->wled_sync_toggle = wled3_sync_toggle;
 		wled->wled_cabc_config = wled5_cabc_config;
 		wled->wled_ovp_delay = wled5_ovp_delay;
 		wled->wled_auto_detection_required =
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
 a Linux Foundation Collaborative Project

[PATCH V4 2/2] backlight: qcom-wled: Correct the sync_toggle sequence

[Kiran Gunda]

As per the current implementation, after FSC (Full Scale Current)
and brightness update the sync bits are set-then-cleared.
But, the FSC and brightness sync takes place when the sync bits are
set (e.g. on a rising edge). So the hardware team recommends a
clear-then-set approach in order to guarantee such a transition
regardless of the previous register state.

Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
---
 drivers/video/backlight/qcom-wled.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index aef52b9..19f83ac 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -337,13 +337,13 @@ static int wled3_sync_toggle(struct wled *wled)
 
 	rc = regmap_update_bits(wled->regmap,
 				wled->ctrl_addr + WLED3_SINK_REG_SYNC,
-				mask, mask);
+				mask, WLED3_SINK_REG_SYNC_CLEAR);
 	if (rc < 0)
 		return rc;
 
 	rc = regmap_update_bits(wled->regmap,
 				wled->ctrl_addr + WLED3_SINK_REG_SYNC,
-				mask, WLED3_SINK_REG_SYNC_CLEAR);
+				mask, mask);
 
 	return rc;
 }
@@ -353,17 +353,17 @@ static int wled5_mod_sync_toggle(struct wled *wled)
 	int rc;
 	u8 val;
 
-	val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
-					     WLED5_SINK_REG_SYNC_MOD_B_BIT;
 	rc = regmap_update_bits(wled->regmap,
 				wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
-				WLED5_SINK_REG_SYNC_MASK, val);
+				WLED5_SINK_REG_SYNC_MASK, 0);
 	if (rc < 0)
 		return rc;
 
+	val = (wled->cfg.mod_sel == MOD_A) ? WLED5_SINK_REG_SYNC_MOD_A_BIT :
+					     WLED5_SINK_REG_SYNC_MOD_B_BIT;
 	return regmap_update_bits(wled->regmap,
 				  wled->sink_addr + WLED5_SINK_REG_MOD_SYNC_BIT,
-				  WLED5_SINK_REG_SYNC_MASK, 0);
+				  WLED5_SINK_REG_SYNC_MASK, val);
 }
 
 static int wled_ovp_fault_status(struct wled *wled, bool *fault_set)
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
 a Linux Foundation Collaborative Project