From 36d33c9a0dcf3938e2df4522ac0a215791b223a5 Mon Sep 17 00:00:00 2001
From: Marijn Suijten <marijn.suijten@somainline.org>
Date: Mon, 15 Nov 2021 21:34:59 +0100
Subject: backlight: qcom-wled: Respect enabled-strings in set_brightness
Git-commit: ec961cf3241153e0f27d850f1bf0f172e7d27a21
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

The hardware is capable of controlling any non-contiguous sequence of
LEDs specified in the DT using qcom,enabled-strings as u32
array, and this also follows from the DT-bindings documentation.  The
numbers specified in this array represent indices of the LED strings
that are to be enabled and disabled.

Its value is appropriately used to setup and enable string modules, but
completely disregarded in the set_brightness paths which only iterate
over the number of strings linearly.
Take an example where only string 2 is enabled with
qcom,enabled_strings=<2>: this string is appropriately enabled but
subsequent brightness changes would have only touched the zero'th
brightness register because num_strings is 1 here.  This is simply
addressed by looking up the string for this index in the enabled_strings
array just like the other codepaths that iterate over num_strings.

Likewise enabled_strings is now also used in the autodetection path for
consistent behaviour: when a list of strings is specified in DT only
those strings will be probed for autodetection, analogous to how the
number of strings that need to be probed is already bound by
qcom,num-strings.  After all autodetection uses the set_brightness
helpers to set an initial value, which could otherwise end up changing
brightness on a different set of strings.

Fixes: 775d2ffb4af6 ("backlight: qcom-wled: Restructure the driver for WLED3")
Fixes: 03b2b5e86986 ("backlight: qcom-wled: Add support for WLED4 peripheral")
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211115203459.1634079-10-marijn.suijten@somainline.org
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/video/backlight/qcom-wled.c |   22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -237,7 +237,7 @@
 
 	for (i = 0; i < wled->cfg.num_strings; ++i) {
 		rc = regmap_bulk_write(wled->regmap, wled->ctrl_addr +
-				       WLED3_SINK_REG_BRIGHT(i),
+				       WLED3_SINK_REG_BRIGHT(wled->cfg.enabled_strings[i]),
 				       &v, sizeof(v));
 		if (rc < 0)
 			return rc;
@@ -260,7 +260,7 @@
 
 	for (i = 0; i < wled->cfg.num_strings; ++i) {
 		rc = regmap_bulk_write(wled->regmap, wled->sink_addr +
-				       WLED4_SINK_REG_BRIGHT(i),
+				       WLED4_SINK_REG_BRIGHT(wled->cfg.enabled_strings[i]),
 				       &v, sizeof(v));
 		if (rc < 0)
 			return rc;
@@ -571,7 +571,7 @@
 
 static void wled_auto_string_detection(struct wled *wled)
 {
-	int rc = 0, i, delay_time_us;
+	int rc = 0, i, j, delay_time_us;
 	u32 sink_config = 0;
 	u8 sink_test = 0, sink_valid = 0, val;
 	bool fault_set;
@@ -618,14 +618,15 @@
 
 	/* Iterate through the strings one by one */
 	for (i = 0; i < wled->cfg.num_strings; i++) {
-		sink_test = BIT((WLED4_SINK_REG_CURR_SINK_SHFT + i));
+		j = wled->cfg.enabled_strings[i];
+		sink_test = BIT((WLED4_SINK_REG_CURR_SINK_SHFT + j));
 
 		/* Enable feedback control */
 		rc = regmap_write(wled->regmap, wled->ctrl_addr +
-				  WLED3_CTRL_REG_FEEDBACK_CONTROL, i + 1);
+				  WLED3_CTRL_REG_FEEDBACK_CONTROL, j + 1);
 		if (rc < 0) {
 			dev_err(wled->dev, "Failed to enable feedback for SINK %d rc = %d\n",
-				i + 1, rc);
+				j + 1, rc);
 			goto failed_detect;
 		}
 
@@ -634,7 +635,7 @@
 				  WLED4_SINK_REG_CURR_SINK, sink_test);
 		if (rc < 0) {
 			dev_err(wled->dev, "Failed to configure SINK %d rc=%d\n",
-				i + 1, rc);
+				j + 1, rc);
 			goto failed_detect;
 		}
 
@@ -661,7 +662,7 @@
 
 		if (fault_set)
 			dev_dbg(wled->dev, "WLED OVP fault detected with SINK %d\n",
-				i + 1);
+				j + 1);
 		else
 			sink_valid |= sink_test;
 
@@ -701,15 +702,16 @@
 	/* Enable valid sinks */
 	if (wled->version == 4) {
 		for (i = 0; i < wled->cfg.num_strings; i++) {
+			j = wled->cfg.enabled_strings[i];
 			if (sink_config &
-			    BIT(WLED4_SINK_REG_CURR_SINK_SHFT + i))
+			    BIT(WLED4_SINK_REG_CURR_SINK_SHFT + j))
 				val = WLED4_SINK_REG_STR_MOD_MASK;
 			else
 				/* Disable modulator_en for unused sink */
 				val = 0;
 
 			rc = regmap_write(wled->regmap, wled->sink_addr +
-					  WLED4_SINK_REG_STR_MOD_EN(i), val);
+					  WLED4_SINK_REG_STR_MOD_EN(j), val);
 			if (rc < 0) {
 				dev_err(wled->dev, "Failed to configure MODULATOR_EN rc=%d\n",
 					rc);