[PATCH v2 0/4] ARM: dts: imx6dl-colibri: Unify with changes to Apalis iMX6 device trees.

[PATCH v2 0/4] ARM: dts: imx6dl-colibri: Unify with changes to Apalis iMX6 device trees.

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>


- Follows a change to the SGTL5000 MCLK handling fixed for Apalis iMX6 by
  Fabio.
- Simplify handling of inverted PWM backlight
- Fixes a regression for the capacitive touch introduced with
  https://lore.kernel.org/all/20220411152234.12678-1-max.oss.09@gmail.com/


Changes in v2:
- add reviewed-by tags
- Split the Backlight PWM patch into two patches, a) #pwm-cells 3, b) adapt brightness steps

Max Krummenacher (4):
  ARM: dts: imx6qdl-colibri: Fix capacitive touch reset polarity
  ARM: dts: imx6qdl-colibri: Mux mclk for sgtl5000 with the codec node
  ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight
  ARM: dts: imx6qdl-colibri: backlight pwm: Adapt brightness steps

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

-- 
2.20.1

[PATCH v2 0/4] ARM: dts: imx6dl-colibri: Unify with changes to Apalis iMX6 device trees.

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>


- Follows a change to the SGTL5000 MCLK handling fixed for Apalis iMX6 by
  Fabio.
- Simplify handling of inverted PWM backlight
- Fixes a regression for the capacitive touch introduced with
  https://lore.kernel.org/all/20220411152234.12678-1-max.oss.09@gmail.com/


Changes in v2:
- add reviewed-by tags
- Split the Backlight PWM patch into two patches, a) #pwm-cells 3, b) adapt brightness steps

Max Krummenacher (4):
  ARM: dts: imx6qdl-colibri: Fix capacitive touch reset polarity
  ARM: dts: imx6qdl-colibri: Mux mclk for sgtl5000 with the codec node
  ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight
  ARM: dts: imx6qdl-colibri: backlight pwm: Adapt brightness steps

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

-- 
2.20.1


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[PATCH v2 1/4] ARM: dts: imx6qdl-colibri: Fix capacitive touch reset polarity

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>

The commit feedaacdadfc ("Input: atmel_mxt_ts - fix up inverted RESET
handler") requires the reset GPIO to have GPIO_ACTIVE_LOW.

Fixes: 1524b27c94a6 ("ARM: dts: imx6dl-colibri: Move common nodes to SoM dtsi")
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

---

Changes in v2:
- Added Fabio's 'Reviewed-by'
- Removed blank line in commit text

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/imx6qdl-colibri.dtsi b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
index c383e0e4110c..7df270cea292 100644
--- a/arch/arm/boot/dts/imx6qdl-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
@@ -593,7 +593,7 @@
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_atmel_conn>;
 		reg = <0x4a>;
-		reset-gpios = <&gpio1 14 GPIO_ACTIVE_HIGH>;	/* SODIMM 106 */
+		reset-gpios = <&gpio1 14 GPIO_ACTIVE_LOW>;	/* SODIMM 106 */
 		status = "disabled";
 	};
 };
-- 
2.20.1

[PATCH v2 1/4] ARM: dts: imx6qdl-colibri: Fix capacitive touch reset polarity

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>

The commit feedaacdadfc ("Input: atmel_mxt_ts - fix up inverted RESET
handler") requires the reset GPIO to have GPIO_ACTIVE_LOW.

Fixes: 1524b27c94a6 ("ARM: dts: imx6dl-colibri: Move common nodes to SoM dtsi")
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

---

Changes in v2:
- Added Fabio's 'Reviewed-by'
- Removed blank line in commit text

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/imx6qdl-colibri.dtsi b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
index c383e0e4110c..7df270cea292 100644
--- a/arch/arm/boot/dts/imx6qdl-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
@@ -593,7 +593,7 @@
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_atmel_conn>;
 		reg = <0x4a>;
-		reset-gpios = <&gpio1 14 GPIO_ACTIVE_HIGH>;	/* SODIMM 106 */
+		reset-gpios = <&gpio1 14 GPIO_ACTIVE_LOW>;	/* SODIMM 106 */
 		status = "disabled";
 	};
 };
-- 
2.20.1


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[PATCH v2 2/4] ARM: dts: imx6qdl-colibri: Mux mclk for sgtl5000 with the codec node

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>

Move the pin muxing for MCLK used by the codec to the codec node
instead of placing it inside the audmux pinctrl group.

While no negative effects have been observed this should make sure that
MCLK is provided when the codec driver is probed.

Follows commit fa51e1dc4b91 ("ARM: dts: imx6qdl-apalis: Fix sgtl5000
detection issue")

Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

---

Changes in v2:
- Added Fabio's 'Reviewed-by'

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/arm/boot/dts/imx6qdl-colibri.dtsi b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
index 7df270cea292..f0908b530f86 100644
--- a/arch/arm/boot/dts/imx6qdl-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
@@ -520,6 +520,8 @@
 		compatible = "fsl,sgtl5000";
 		clocks = <&clks IMX6QDL_CLK_CKO>;
 		lrclk-strength = <3>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_sgtl5000>;
 		reg = <0x0a>;
 		#sound-dai-cells = <0>;
 		VDDA-supply = <&reg_module_3v3_audio>;
@@ -739,8 +741,6 @@
 
 	pinctrl_audmux: audmuxgrp {
 		fsl,pins = <
-			/* SGTL5000 sys_mclk */
-			MX6QDL_PAD_GPIO_0__CCM_CLKO1	0x000b0
 			MX6QDL_PAD_KEY_COL0__AUD5_TXC	0x130b0
 			MX6QDL_PAD_KEY_ROW0__AUD5_TXD	0x130b0
 			MX6QDL_PAD_KEY_COL1__AUD5_TXFS	0x130b0
@@ -991,6 +991,13 @@
 		>;
 	};
 
+	pinctrl_sgtl5000: sgtl5000grp {
+		fsl,pins = <
+			/* SGTL5000 sys_mclk */
+			MX6QDL_PAD_GPIO_0__CCM_CLKO1	0x000b0
+		>;
+	};
+
 	pinctrl_spdif: spdifgrp {
 		fsl,pins = <
 			MX6QDL_PAD_GPIO_17__SPDIF_OUT 0x1b0b0
-- 
2.20.1

[PATCH v2 2/4] ARM: dts: imx6qdl-colibri: Mux mclk for sgtl5000 with the codec node

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>

Move the pin muxing for MCLK used by the codec to the codec node
instead of placing it inside the audmux pinctrl group.

While no negative effects have been observed this should make sure that
MCLK is provided when the codec driver is probed.

Follows commit fa51e1dc4b91 ("ARM: dts: imx6qdl-apalis: Fix sgtl5000
detection issue")

Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

---

Changes in v2:
- Added Fabio's 'Reviewed-by'

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/arm/boot/dts/imx6qdl-colibri.dtsi b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
index 7df270cea292..f0908b530f86 100644
--- a/arch/arm/boot/dts/imx6qdl-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
@@ -520,6 +520,8 @@
 		compatible = "fsl,sgtl5000";
 		clocks = <&clks IMX6QDL_CLK_CKO>;
 		lrclk-strength = <3>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_sgtl5000>;
 		reg = <0x0a>;
 		#sound-dai-cells = <0>;
 		VDDA-supply = <&reg_module_3v3_audio>;
@@ -739,8 +741,6 @@
 
 	pinctrl_audmux: audmuxgrp {
 		fsl,pins = <
-			/* SGTL5000 sys_mclk */
-			MX6QDL_PAD_GPIO_0__CCM_CLKO1	0x000b0
 			MX6QDL_PAD_KEY_COL0__AUD5_TXC	0x130b0
 			MX6QDL_PAD_KEY_ROW0__AUD5_TXD	0x130b0
 			MX6QDL_PAD_KEY_COL1__AUD5_TXFS	0x130b0
@@ -991,6 +991,13 @@
 		>;
 	};
 
+	pinctrl_sgtl5000: sgtl5000grp {
+		fsl,pins = <
+			/* SGTL5000 sys_mclk */
+			MX6QDL_PAD_GPIO_0__CCM_CLKO1	0x000b0
+		>;
+	};
+
 	pinctrl_spdif: spdifgrp {
 		fsl,pins = <
 			MX6QDL_PAD_GPIO_17__SPDIF_OUT 0x1b0b0
-- 
2.20.1


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[PATCH v2 3/4] ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>

Set #pwm-cells to the default 3 to gain access to the parameter
which allows inverting the PWM signal. This is useful to specify
a backlight which has its highest brightness at 0.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

---

Changes in v2:
- Split to two patches as proposed by Fabio Estevam

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/boot/dts/imx6qdl-colibri.dtsi b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
index f0908b530f86..d91fae92c90a 100644
--- a/arch/arm/boot/dts/imx6qdl-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
@@ -6,6 +6,7 @@
  */
 
 #include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/pwm/pwm.h>
 
 / {
 	model = "Toradex Colibri iMX6DL/S Module";
@@ -13,13 +14,13 @@
 
 	backlight: backlight {
 		compatible = "pwm-backlight";
-		brightness-levels = <0 127 191 223 239 247 251 255>;
-		default-brightness-level = <1>;
+		brightness-levels = <0 4 8 16 32 64 128 255>;
+		default-brightness-level = <6>;
 		enable-gpios = <&gpio3 26 GPIO_ACTIVE_HIGH>; /* Colibri BL_ON */
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_gpio_bl_on>;
 		power-supply = <&reg_module_3v3>;
-		pwms = <&pwm3 0 5000000>;
+		pwms = <&pwm3 0 5000000 PWM_POLARITY_INVERTED>;
 		status = "disabled";
 	};
 
@@ -620,7 +621,6 @@
 
 /* Colibri PWM<A> */
 &pwm3 {
-	#pwm-cells = <2>;
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_pwm3>;
 	status = "disabled";
-- 
2.20.1

[PATCH v2 3/4] ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>

Set #pwm-cells to the default 3 to gain access to the parameter
which allows inverting the PWM signal. This is useful to specify
a backlight which has its highest brightness at 0.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

---

Changes in v2:
- Split to two patches as proposed by Fabio Estevam

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/boot/dts/imx6qdl-colibri.dtsi b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
index f0908b530f86..d91fae92c90a 100644
--- a/arch/arm/boot/dts/imx6qdl-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
@@ -6,6 +6,7 @@
  */
 
 #include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/pwm/pwm.h>
 
 / {
 	model = "Toradex Colibri iMX6DL/S Module";
@@ -13,13 +14,13 @@
 
 	backlight: backlight {
 		compatible = "pwm-backlight";
-		brightness-levels = <0 127 191 223 239 247 251 255>;
-		default-brightness-level = <1>;
+		brightness-levels = <0 4 8 16 32 64 128 255>;
+		default-brightness-level = <6>;
 		enable-gpios = <&gpio3 26 GPIO_ACTIVE_HIGH>; /* Colibri BL_ON */
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_gpio_bl_on>;
 		power-supply = <&reg_module_3v3>;
-		pwms = <&pwm3 0 5000000>;
+		pwms = <&pwm3 0 5000000 PWM_POLARITY_INVERTED>;
 		status = "disabled";
 	};
 
@@ -620,7 +621,6 @@
 
 /* Colibri PWM<A> */
 &pwm3 {
-	#pwm-cells = <2>;
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_pwm3>;
 	status = "disabled";
-- 
2.20.1


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[PATCH v2 4/4] ARM: dts: imx6qdl-colibri: backlight pwm: Adapt brightness steps

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>

Adapt the brightness steps as the backlight doesn't light up
for very low duty cycles.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

---

Changes in v2:
- add reviewed-by tags
- Split the Backlight PWM patch into two patches, a) #pwm-cells 3, b) adapt brightness steps
- Split to two patches as proposed by Fabio Estevam

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/boot/dts/imx6qdl-colibri.dtsi b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
index d91fae92c90a..023e76215064 100644
--- a/arch/arm/boot/dts/imx6qdl-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
@@ -14,8 +14,8 @@
 
 	backlight: backlight {
 		compatible = "pwm-backlight";
-		brightness-levels = <0 4 8 16 32 64 128 255>;
-		default-brightness-level = <6>;
+		brightness-levels = <0 45 63 88 119 158 203 255>;
+		default-brightness-level = <4>;
 		enable-gpios = <&gpio3 26 GPIO_ACTIVE_HIGH>; /* Colibri BL_ON */
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_gpio_bl_on>;
-- 
2.20.1

[PATCH v2 4/4] ARM: dts: imx6qdl-colibri: backlight pwm: Adapt brightness steps

[Max Krummenacher]

From: Max Krummenacher <max.krummenacher@toradex.com>

Adapt the brightness steps as the backlight doesn't light up
for very low duty cycles.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

---

Changes in v2:
- add reviewed-by tags
- Split the Backlight PWM patch into two patches, a) #pwm-cells 3, b) adapt brightness steps
- Split to two patches as proposed by Fabio Estevam

 arch/arm/boot/dts/imx6qdl-colibri.dtsi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/boot/dts/imx6qdl-colibri.dtsi b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
index d91fae92c90a..023e76215064 100644
--- a/arch/arm/boot/dts/imx6qdl-colibri.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-colibri.dtsi
@@ -14,8 +14,8 @@
 
 	backlight: backlight {
 		compatible = "pwm-backlight";
-		brightness-levels = <0 4 8 16 32 64 128 255>;
-		default-brightness-level = <6>;
+		brightness-levels = <0 45 63 88 119 158 203 255>;
+		default-brightness-level = <4>;
 		enable-gpios = <&gpio3 26 GPIO_ACTIVE_HIGH>; /* Colibri BL_ON */
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_gpio_bl_on>;
-- 
2.20.1


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Re: [PATCH v2 4/4] ARM: dts: imx6qdl-colibri: backlight pwm: Adapt brightness steps

[Fabio Estevam]

On Wed, May 11, 2022 at 8:59 AM Max Krummenacher <max.oss.09@gmail.com> wrote:
>
> From: Max Krummenacher <max.krummenacher@toradex.com>
>
> Adapt the brightness steps as the backlight doesn't light up
> for very low duty cycles.
>
> Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

Reviewed-by: Fabio Estevam <festevam@gmail.com>

Re: [PATCH v2 4/4] ARM: dts: imx6qdl-colibri: backlight pwm: Adapt brightness steps

[Fabio Estevam]

On Wed, May 11, 2022 at 8:59 AM Max Krummenacher <max.oss.09@gmail.com> wrote:
>
> From: Max Krummenacher <max.krummenacher@toradex.com>
>
> Adapt the brightness steps as the backlight doesn't light up
> for very low duty cycles.
>
> Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

Reviewed-by: Fabio Estevam <festevam@gmail.com>

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Re: [PATCH v2 3/4] ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight

[Fabio Estevam]

On Wed, May 11, 2022 at 8:59 AM Max Krummenacher <max.oss.09@gmail.com> wrote:

>         backlight: backlight {
>                 compatible = "pwm-backlight";
> -               brightness-levels = <0 127 191 223 239 247 251 255>;
> -               default-brightness-level = <1>;
> +               brightness-levels = <0 4 8 16 32 64 128 255>;
> +               default-brightness-level = <6>;

In this patch, you are still changing the brightness levels + passing
the polarity.

I would suggest that this patch only touches the PWM polarity.

The next patch could fix the brightness levels.

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Re: [PATCH v2 3/4] ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight

[Fabio Estevam]

On Wed, May 11, 2022 at 8:59 AM Max Krummenacher <max.oss.09@gmail.com> wrote:

>         backlight: backlight {
>                 compatible = "pwm-backlight";
> -               brightness-levels = <0 127 191 223 239 247 251 255>;
> -               default-brightness-level = <1>;
> +               brightness-levels = <0 4 8 16 32 64 128 255>;
> +               default-brightness-level = <6>;

In this patch, you are still changing the brightness levels + passing
the polarity.

I would suggest that this patch only touches the PWM polarity.

The next patch could fix the brightness levels.

Re: [PATCH v2 3/4] ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight

[Max Krummenacher]

Hi Fabio

On Wed, May 11, 2022 at 2:07 PM Fabio Estevam <festevam@gmail.com> wrote:
>
> On Wed, May 11, 2022 at 8:59 AM Max Krummenacher <max.oss.09@gmail.com> wrote:
>
> >         backlight: backlight {
> >                 compatible = "pwm-backlight";
> > -               brightness-levels = <0 127 191 223 239 247 251 255>;
> > -               default-brightness-level = <1>;
> > +               brightness-levels = <0 4 8 16 32 64 128 255>;
> > +               default-brightness-level = <6>;
>
> In this patch, you are still changing the brightness levels + passing
> the polarity.
>
> I would suggest that this patch only touches the PWM polarity.

I disagree. Just setting the invert without at the same changing the
brightness-levels does
change the user experience way more than when one adapts the available
duty cycles
at the same time.

With the change to use the PWM with inverted polarity the PWM signals
is inverted to
how it was before this patch. Keeping the brightness-levels will then
have a big brightness
jump from 0 to 127 duty cycle, the other 6 steps will then be barely noticable.

I.e. before the change the brightness for level [0..7] was
['off', 128/255, 64/255, 32/255, 16/255, 8/255, 4/255, 'off'],
if one only inverts the polarity it will be
['off', 128/255, 191/255, 223/255, 239/255, 247/255, 255/255].
With the proposed patch it will be
['off', 4/255, 8/255, 16/255, 32/255, 64/255, 128/255, 255/255].

Max

> The next patch could fix the brightness levels.

Re: [PATCH v2 3/4] ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight

[Max Krummenacher]

Hi Fabio

On Wed, May 11, 2022 at 2:07 PM Fabio Estevam <festevam@gmail.com> wrote:
>
> On Wed, May 11, 2022 at 8:59 AM Max Krummenacher <max.oss.09@gmail.com> wrote:
>
> >         backlight: backlight {
> >                 compatible = "pwm-backlight";
> > -               brightness-levels = <0 127 191 223 239 247 251 255>;
> > -               default-brightness-level = <1>;
> > +               brightness-levels = <0 4 8 16 32 64 128 255>;
> > +               default-brightness-level = <6>;
>
> In this patch, you are still changing the brightness levels + passing
> the polarity.
>
> I would suggest that this patch only touches the PWM polarity.

I disagree. Just setting the invert without at the same changing the
brightness-levels does
change the user experience way more than when one adapts the available
duty cycles
at the same time.

With the change to use the PWM with inverted polarity the PWM signals
is inverted to
how it was before this patch. Keeping the brightness-levels will then
have a big brightness
jump from 0 to 127 duty cycle, the other 6 steps will then be barely noticable.

I.e. before the change the brightness for level [0..7] was
['off', 128/255, 64/255, 32/255, 16/255, 8/255, 4/255, 'off'],
if one only inverts the polarity it will be
['off', 128/255, 191/255, 223/255, 239/255, 247/255, 255/255].
With the proposed patch it will be
['off', 4/255, 8/255, 16/255, 32/255, 64/255, 128/255, 255/255].

Max

> The next patch could fix the brightness levels.

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Re: [PATCH v2 3/4] ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight

[Fabio Estevam]

On Wed, May 11, 2022 at 10:32 AM Max Krummenacher <max.oss.09@gmail.com> wrote:

> I disagree. Just setting the invert without at the same changing the
> brightness-levels does
> change the user experience way more than when one adapts the available
> duty cycles
> at the same time.
>
> With the change to use the PWM with inverted polarity the PWM signals
> is inverted to
> how it was before this patch. Keeping the brightness-levels will then
> have a big brightness
> jump from 0 to 127 duty cycle, the other 6 steps will then be barely noticable.
>
> I.e. before the change the brightness for level [0..7] was
> ['off', 128/255, 64/255, 32/255, 16/255, 8/255, 4/255, 'off'],
> if one only inverts the polarity it will be
> ['off', 128/255, 191/255, 223/255, 239/255, 247/255, 255/255].
> With the proposed patch it will be
> ['off', 4/255, 8/255, 16/255, 32/255, 64/255, 128/255, 255/255].

Ok, please add an explanation to the commit log as to why you are
changing the brightness levels
like you did here. Thanks

Re: [PATCH v2 3/4] ARM: dts: imx6qdl-colibri: backlight pwm: Simplify inverted backlight

[Fabio Estevam]

On Wed, May 11, 2022 at 10:32 AM Max Krummenacher <max.oss.09@gmail.com> wrote:

> I disagree. Just setting the invert without at the same changing the
> brightness-levels does
> change the user experience way more than when one adapts the available
> duty cycles
> at the same time.
>
> With the change to use the PWM with inverted polarity the PWM signals
> is inverted to
> how it was before this patch. Keeping the brightness-levels will then
> have a big brightness
> jump from 0 to 127 duty cycle, the other 6 steps will then be barely noticable.
>
> I.e. before the change the brightness for level [0..7] was
> ['off', 128/255, 64/255, 32/255, 16/255, 8/255, 4/255, 'off'],
> if one only inverts the polarity it will be
> ['off', 128/255, 191/255, 223/255, 239/255, 247/255, 255/255].
> With the proposed patch it will be
> ['off', 4/255, 8/255, 16/255, 32/255, 64/255, 128/255, 255/255].

Ok, please add an explanation to the commit log as to why you are
changing the brightness levels
like you did here. Thanks

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