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* [PATCH V3 1/2] backlight: qcom-wled: Fix FSC update issue for WLED5
       [not found] <1614590916-27070-1-git-send-email-kgunda@codeaurora.org>
@ 2021-03-01  9:28 ` Kiran Gunda
  2021-03-01  9:28 ` [PATCH V3 2/2] backlight: qcom-wled: Correct the sync_toggle sequence Kiran Gunda
  1 sibling, 0 replies; 4+ messages in thread
From: Kiran Gunda @ 2021-03-01  9:28 UTC (permalink / raw)
  To: bjorn.andersson, jingoohan1, lee.jones, b.zolnierkie, dri-devel,
	daniel.thompson, jacek.anaszewski, pavel, robh+dt, mark.rutland,
	linux-leds, devicetree, linux-kernel, Andy Gross, linux-arm-msm,
	linux-fbdev
  Cc: phone-devel, 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


^ permalink raw reply	[flat|nested] 4+ messages in thread

* [PATCH V3 2/2] backlight: qcom-wled: Correct the sync_toggle sequence
       [not found] <1614590916-27070-1-git-send-email-kgunda@codeaurora.org>
  2021-03-01  9:28 ` [PATCH V3 1/2] backlight: qcom-wled: Fix FSC update issue for WLED5 Kiran Gunda
@ 2021-03-01  9:28 ` Kiran Gunda
  2021-03-01 10:02   ` Daniel Thompson
  1 sibling, 1 reply; 4+ messages in thread
From: Kiran Gunda @ 2021-03-01  9:28 UTC (permalink / raw)
  To: bjorn.andersson, jingoohan1, lee.jones, b.zolnierkie, dri-devel,
	daniel.thompson, jacek.anaszewski, pavel, robh+dt, mark.rutland,
	linux-leds, devicetree, linux-kernel, Andy Gross, linux-arm-msm,
	linux-fbdev
  Cc: phone-devel, Kiran Gunda

As per the current implementation, after FSC (Full Scale Current)
and brightness update the sync bits are transitioned from set-then-clear.
But, the FSC and brightness sync takes place during a clear-then-set
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


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH V3 2/2] backlight: qcom-wled: Correct the sync_toggle sequence
  2021-03-01  9:28 ` [PATCH V3 2/2] backlight: qcom-wled: Correct the sync_toggle sequence Kiran Gunda
@ 2021-03-01 10:02   ` Daniel Thompson
  2021-03-01 16:42     ` kgunda
  0 siblings, 1 reply; 4+ messages in thread
From: Daniel Thompson @ 2021-03-01 10:02 UTC (permalink / raw)
  To: Kiran Gunda
  Cc: bjorn.andersson, jingoohan1, lee.jones, b.zolnierkie, dri-devel,
	jacek.anaszewski, pavel, robh+dt, mark.rutland, linux-leds,
	devicetree, linux-kernel, Andy Gross, linux-arm-msm, linux-fbdev,
	phone-devel

On Mon, Mar 01, 2021 at 02:58:36PM +0530, Kiran Gunda wrote:
> As per the current implementation, after FSC (Full Scale Current)
> and brightness update the sync bits are transitioned from set-then-clear.

This does not makes sense since there are too many verbs. Set and clear
are both verbs so in this context: "the code will set the bit and then
the code will clear the bit".

Either:

s/transitioned from set-then-clear/set-then-cleared/.

Or:

s/transitioned from set-then-clear/using a set-then-clear approach/.

> But, the FSC and brightness sync takes place during a clear-then-set
> transition of the sync bits.

Likewise this no longer makes sense and had also become misleading.
Two changes of state, clear and then set, do not usually result in a
single transition.

Either:

s/clear-then-set/0 to 1/

Alternatively, if you want to stick exclusively to the set/clear
terminology then replace the whole quoted section with:

  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>

With one of each of the changes proposed above:
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>


Daniel.


> ---
>  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
> 

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH V3 2/2] backlight: qcom-wled: Correct the sync_toggle sequence
  2021-03-01 10:02   ` Daniel Thompson
@ 2021-03-01 16:42     ` kgunda
  0 siblings, 0 replies; 4+ messages in thread
From: kgunda @ 2021-03-01 16:42 UTC (permalink / raw)
  To: Daniel Thompson
  Cc: bjorn.andersson, jingoohan1, lee.jones, b.zolnierkie, dri-devel,
	jacek.anaszewski, pavel, robh+dt, mark.rutland, linux-leds,
	devicetree, linux-kernel, Andy Gross, linux-arm-msm, linux-fbdev,
	phone-devel

On 2021-03-01 15:32, Daniel Thompson wrote:
> On Mon, Mar 01, 2021 at 02:58:36PM +0530, Kiran Gunda wrote:
>> As per the current implementation, after FSC (Full Scale Current)
>> and brightness update the sync bits are transitioned from 
>> set-then-clear.
> 
> This does not makes sense since there are too many verbs. Set and clear
> are both verbs so in this context: "the code will set the bit and then
> the code will clear the bit".
> 
> Either:
> 
> s/transitioned from set-then-clear/set-then-cleared/.
> 
> Or:
> 
> s/transitioned from set-then-clear/using a set-then-clear approach/.
> 
>> But, the FSC and brightness sync takes place during a clear-then-set
>> transition of the sync bits.
> 
> Likewise this no longer makes sense and had also become misleading.
> Two changes of state, clear and then set, do not usually result in a
> single transition.
> 
> Either:
> 
> s/clear-then-set/0 to 1/
> 
> Alternatively, if you want to stick exclusively to the set/clear
> terminology then replace the whole quoted section with:
> 
>   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>
> 
> With one of each of the changes proposed above:
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> 
> 
> Daniel.
> 
Apologies for the mistake. I have corrected and submitted the
V4 series with the "reviewed-by" tag.
> 
>> ---
>>  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
>> 

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-03-01 16:46 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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     [not found] <1614590916-27070-1-git-send-email-kgunda@codeaurora.org>
2021-03-01  9:28 ` [PATCH V3 1/2] backlight: qcom-wled: Fix FSC update issue for WLED5 Kiran Gunda
2021-03-01  9:28 ` [PATCH V3 2/2] backlight: qcom-wled: Correct the sync_toggle sequence Kiran Gunda
2021-03-01 10:02   ` Daniel Thompson
2021-03-01 16:42     ` kgunda

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