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From: Kiran Gunda <kgunda@codeaurora.org>
To: bjorn.andersson@linaro.org, jingoohan1@gmail.com,
	lee.jones@linaro.org, b.zolnierkie@samsung.com,
	dri-devel@lists.freedesktop.org, daniel.thompson@linaro.org,
	jacek.anaszewski@gmail.com, pavel@ucw.cz, robh+dt@kernel.org,
	mark.rutland@arm.com, linux-leds@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	Andy Gross <agross@kernel.org>,
	linux-arm-msm@vger.kernel.org, linux-fbdev@vger.kernel.org
Cc: phone-devel@vger.kernel.org, Kiran Gunda <kgunda@codeaurora.org>
Subject: [PATCH V2 2/2] backlight: qcom-wled: Correct the sync_toggle sequence
Date: Fri, 26 Feb 2021 17:42:24 +0530	[thread overview]
Message-ID: <1614341544-5306-3-git-send-email-kgunda@codeaurora.org> (raw)
In-Reply-To: <1614341544-5306-1-git-send-email-kgunda@codeaurora.org>

As per the current implementation, after FSC (Full Scale Current)
and brightness update the sync bits are transitioned from 1 to 0.
But, the FSC and brightness sync takes place during a 0 to 1
transition of the sync bits. 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>
---
 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


WARNING: multiple messages have this Message-ID (diff)
From: Kiran Gunda <kgunda@codeaurora.org>
To: bjorn.andersson@linaro.org, jingoohan1@gmail.com,
	lee.jones@linaro.org, b.zolnierkie@samsung.com,
	dri-devel@lists.freedesktop.org, daniel.thompson@linaro.org,
	jacek.anaszewski@gmail.com, pavel@ucw.cz, robh+dt@kernel.org,
	mark.rutland@arm.com, linux-leds@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	Andy Gross <agross@kernel.org>,
	linux-arm-msm@vger.kernel.org, linux-fbdev@vger.kernel.org
Cc: phone-devel@vger.kernel.org, Kiran Gunda <kgunda@codeaurora.org>
Subject: [PATCH V2 2/2] backlight: qcom-wled: Correct the sync_toggle sequence
Date: Fri, 26 Feb 2021 17:42:24 +0530	[thread overview]
Message-ID: <1614341544-5306-3-git-send-email-kgunda@codeaurora.org> (raw)
In-Reply-To: <1614341544-5306-1-git-send-email-kgunda@codeaurora.org>

As per the current implementation, after FSC (Full Scale Current)
and brightness update the sync bits are transitioned from 1 to 0.
But, the FSC and brightness sync takes place during a 0 to 1
transition of the sync bits. 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>
---
 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

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

  parent reply	other threads:[~2021-02-26 12:14 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-26 12:12 [PATCH V2 0/2] Fix WLED FSC Sync and brightness Sync settings Kiran Gunda
2021-02-26 12:12 ` Kiran Gunda
2021-02-26 12:12 ` [PATCH V2 1/2] backlight: qcom-wled: Fix FSC update issue for WLED5 Kiran Gunda
2021-02-26 12:12   ` Kiran Gunda
2021-02-26 17:09   ` Daniel Thompson
2021-02-26 17:09     ` Daniel Thompson
2021-02-26 12:12 ` Kiran Gunda [this message]
2021-02-26 12:12   ` [PATCH V2 2/2] backlight: qcom-wled: Correct the sync_toggle sequence Kiran Gunda
2021-02-26 17:26   ` Daniel Thompson
2021-02-26 17:26     ` Daniel Thompson
2021-03-01  8:45     ` kgunda
2021-03-01  8:45       ` kgunda
2021-03-01  9:39       ` Daniel Thompson
2021-03-01  9:39         ` Daniel Thompson

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