[PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Alexey Charkov]

Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
comes physically attached to Rockchip RK3576 EVB1 boards.

The display part is driven by the on-chip MIPI DSI controller, and the
touchscreen is connected over I2C.

Signed-off-by: Alexey Charkov <alchark@gmail.com>
---
Note that backlight support is left out for now, as it depends on PWM
support [0] which has not yet been merged.

A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
pin high and thus to light up the display unconditionally.

[0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
---
 arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
index db8fef7a4f1b9570cb517ccc9a857d1c93c9d2db..f20cd6f2c079e0a5bd79acc9ebcd56b499e0f72f 100644
--- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
@@ -125,6 +125,8 @@ vcc3v3_lcd_n: regulator-vcc3v3-lcd0-n {
 		regulator-boot-on;
 		enable-active-high;
 		gpio = <&gpio0 RK_PC6 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&vcc3v3_lcd_s0_en>;
 		vin-supply = <&vcc_3v3_s0>;
 	};
 
@@ -264,6 +266,43 @@ &combphy1_psu {
 	status = "okay";
 };
 
+&dsi {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	pinctrl-0 = <&mipim1_pins>;
+	pinctrl-names = "default";
+	status = "okay";
+
+	panel@0 {
+		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
+		reg = <0>;
+
+		iovcc-supply = <&vcc3v3_lcd_n>;
+		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
+		vdd-supply = <&vcc3v3_lcd_n>;
+		vsn-supply = <&vcc5v0_device>;
+		vsp-supply = <&vcc5v0_device>;
+
+		port {
+			mipi_panel_in: endpoint {
+				remote-endpoint = <&dsi_out_panel>;
+			};
+		};
+	};
+};
+
+&dsi_in {
+	dsi_in_vp1: endpoint {
+		remote-endpoint = <&vp1_out_dsi>;
+	};
+};
+
+&dsi_out {
+	dsi_out_panel: endpoint {
+		remote-endpoint = <&mipi_panel_in>;
+	};
+};
+
 &gmac0 {
 	clock_in_out = "output";
 	phy-mode = "rgmii-rxid";
@@ -319,6 +358,28 @@ &hdptxphy {
 	status = "okay";
 };
 
+&i2c0 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&i2c0m1_xfer>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+	status = "okay";
+
+	touchscreen@14 {
+		compatible = "goodix,gt1158";
+		reg = <0x14>;
+		interrupt-parent = <&gpio0>;
+		interrupts = <RK_PC5 IRQ_TYPE_LEVEL_LOW>;
+		irq-gpios = <&gpio0 RK_PC5 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&tp_int>, <&tp_rst>;
+		reset-gpios = <&gpio0 RK_PD0 GPIO_ACTIVE_HIGH>;
+		touchscreen-size-x = <720>;
+		touchscreen-size-y = <1280>;
+		VDDIO-supply = <&vcc3v3_lcd_n>;
+	};
+};
+
 &i2c1 {
 	status = "okay";
 
@@ -738,6 +799,10 @@ rgmii_phy1: ethernet-phy@1 {
 	};
 };
 
+&mipidcphy {
+	status = "okay";
+};
+
 &pcie0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pcie0_rst>;
@@ -788,6 +853,20 @@ host_wake_bt: host-wake-bt {
 		};
 	};
 
+	display {
+		vcc3v3_lcd_s0_en: vcc3v3-lcd-s0-en {
+			rockchip,pins = <0 RK_PC6 0 &pcfg_pull_none>;
+		};
+
+		tp_int: tp-int {
+			rockchip,pins = <0 RK_PC5 0 &pcfg_pull_none>;
+		};
+
+		tp_rst: tp-rst {
+			rockchip,pins = <0 RK_PD0 0 &pcfg_pull_none>;
+		};
+	};
+
 	hym8563 {
 		rtc_int: rtc-int {
 			rockchip,pins = <0 RK_PA0 RK_FUNC_GPIO &pcfg_pull_up>;
@@ -941,3 +1020,13 @@ vp0_out_hdmi: endpoint@ROCKCHIP_VOP2_EP_HDMI0 {
 		remote-endpoint = <&hdmi_in_vp0>;
 	};
 };
+
+&vp1 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	vp1_out_dsi: endpoint@ROCKCHIP_VOP2_EP_MIPI0 {
+		reg = <ROCKCHIP_VOP2_EP_MIPI0>;
+		remote-endpoint = <&dsi_in_vp1>;
+	};
+};

---
base-commit: ce7f1a983b074f6cf8609068088ca3182c569ee4
change-id: 20250924-rk3576-evb1-dsi-e39f34833bf6

Best regards,
-- 
Alexey Charkov <alchark@gmail.com>

[PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Alexey Charkov]

Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
comes physically attached to Rockchip RK3576 EVB1 boards.

The display part is driven by the on-chip MIPI DSI controller, and the
touchscreen is connected over I2C.

Signed-off-by: Alexey Charkov <alchark@gmail.com>
---
Note that backlight support is left out for now, as it depends on PWM
support [0] which has not yet been merged.

A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
pin high and thus to light up the display unconditionally.

[0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
---
 arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
index db8fef7a4f1b9570cb517ccc9a857d1c93c9d2db..f20cd6f2c079e0a5bd79acc9ebcd56b499e0f72f 100644
--- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
@@ -125,6 +125,8 @@ vcc3v3_lcd_n: regulator-vcc3v3-lcd0-n {
 		regulator-boot-on;
 		enable-active-high;
 		gpio = <&gpio0 RK_PC6 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&vcc3v3_lcd_s0_en>;
 		vin-supply = <&vcc_3v3_s0>;
 	};
 
@@ -264,6 +266,43 @@ &combphy1_psu {
 	status = "okay";
 };
 
+&dsi {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	pinctrl-0 = <&mipim1_pins>;
+	pinctrl-names = "default";
+	status = "okay";
+
+	panel@0 {
+		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
+		reg = <0>;
+
+		iovcc-supply = <&vcc3v3_lcd_n>;
+		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
+		vdd-supply = <&vcc3v3_lcd_n>;
+		vsn-supply = <&vcc5v0_device>;
+		vsp-supply = <&vcc5v0_device>;
+
+		port {
+			mipi_panel_in: endpoint {
+				remote-endpoint = <&dsi_out_panel>;
+			};
+		};
+	};
+};
+
+&dsi_in {
+	dsi_in_vp1: endpoint {
+		remote-endpoint = <&vp1_out_dsi>;
+	};
+};
+
+&dsi_out {
+	dsi_out_panel: endpoint {
+		remote-endpoint = <&mipi_panel_in>;
+	};
+};
+
 &gmac0 {
 	clock_in_out = "output";
 	phy-mode = "rgmii-rxid";
@@ -319,6 +358,28 @@ &hdptxphy {
 	status = "okay";
 };
 
+&i2c0 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&i2c0m1_xfer>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+	status = "okay";
+
+	touchscreen@14 {
+		compatible = "goodix,gt1158";
+		reg = <0x14>;
+		interrupt-parent = <&gpio0>;
+		interrupts = <RK_PC5 IRQ_TYPE_LEVEL_LOW>;
+		irq-gpios = <&gpio0 RK_PC5 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&tp_int>, <&tp_rst>;
+		reset-gpios = <&gpio0 RK_PD0 GPIO_ACTIVE_HIGH>;
+		touchscreen-size-x = <720>;
+		touchscreen-size-y = <1280>;
+		VDDIO-supply = <&vcc3v3_lcd_n>;
+	};
+};
+
 &i2c1 {
 	status = "okay";
 
@@ -738,6 +799,10 @@ rgmii_phy1: ethernet-phy@1 {
 	};
 };
 
+&mipidcphy {
+	status = "okay";
+};
+
 &pcie0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pcie0_rst>;
@@ -788,6 +853,20 @@ host_wake_bt: host-wake-bt {
 		};
 	};
 
+	display {
+		vcc3v3_lcd_s0_en: vcc3v3-lcd-s0-en {
+			rockchip,pins = <0 RK_PC6 0 &pcfg_pull_none>;
+		};
+
+		tp_int: tp-int {
+			rockchip,pins = <0 RK_PC5 0 &pcfg_pull_none>;
+		};
+
+		tp_rst: tp-rst {
+			rockchip,pins = <0 RK_PD0 0 &pcfg_pull_none>;
+		};
+	};
+
 	hym8563 {
 		rtc_int: rtc-int {
 			rockchip,pins = <0 RK_PA0 RK_FUNC_GPIO &pcfg_pull_up>;
@@ -941,3 +1020,13 @@ vp0_out_hdmi: endpoint@ROCKCHIP_VOP2_EP_HDMI0 {
 		remote-endpoint = <&hdmi_in_vp0>;
 	};
 };
+
+&vp1 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	vp1_out_dsi: endpoint@ROCKCHIP_VOP2_EP_MIPI0 {
+		reg = <ROCKCHIP_VOP2_EP_MIPI0>;
+		remote-endpoint = <&dsi_in_vp1>;
+	};
+};

---
base-commit: ce7f1a983b074f6cf8609068088ca3182c569ee4
change-id: 20250924-rk3576-evb1-dsi-e39f34833bf6

Best regards,
-- 
Alexey Charkov <alchark@gmail.com>


_______________________________________________
Linux-rockchip mailing list
Linux-rockchip@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-rockchip

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Alexey Charkov]

On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
>
> Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> comes physically attached to Rockchip RK3576 EVB1 boards.
>
> The display part is driven by the on-chip MIPI DSI controller, and the
> touchscreen is connected over I2C.
>
> Signed-off-by: Alexey Charkov <alchark@gmail.com>
> ---
> Note that backlight support is left out for now, as it depends on PWM
> support [0] which has not yet been merged.
>
> A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> pin high and thus to light up the display unconditionally.
>
> [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> ---
>  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
>  1 file changed, 89 insertions(+)

Hi Heiko,

Any thoughts about this one? Can we perhaps get it merged for -next?

Thanks a lot,
Alexey

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Alexey Charkov]

On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
>
> Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> comes physically attached to Rockchip RK3576 EVB1 boards.
>
> The display part is driven by the on-chip MIPI DSI controller, and the
> touchscreen is connected over I2C.
>
> Signed-off-by: Alexey Charkov <alchark@gmail.com>
> ---
> Note that backlight support is left out for now, as it depends on PWM
> support [0] which has not yet been merged.
>
> A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> pin high and thus to light up the display unconditionally.
>
> [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> ---
>  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
>  1 file changed, 89 insertions(+)

Hi Heiko,

Any thoughts about this one? Can we perhaps get it merged for -next?

Thanks a lot,
Alexey

_______________________________________________
Linux-rockchip mailing list
Linux-rockchip@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-rockchip

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Heiko Stuebner]

Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> >
> > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > comes physically attached to Rockchip RK3576 EVB1 boards.
> >
> > The display part is driven by the on-chip MIPI DSI controller, and the
> > touchscreen is connected over I2C.
> >
> > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > ---
> > Note that backlight support is left out for now, as it depends on PWM
> > support [0] which has not yet been merged.
> >
> > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > pin high and thus to light up the display unconditionally.
> >
> > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > ---
> >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> >  1 file changed, 89 insertions(+)
> 
> Hi Heiko,
> 
> Any thoughts about this one? Can we perhaps get it merged for -next?

Does the gpio-backlight work on that device?
That would make the gpioset hack unnecessary.


Heiko

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Heiko Stuebner]

Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> >
> > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > comes physically attached to Rockchip RK3576 EVB1 boards.
> >
> > The display part is driven by the on-chip MIPI DSI controller, and the
> > touchscreen is connected over I2C.
> >
> > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > ---
> > Note that backlight support is left out for now, as it depends on PWM
> > support [0] which has not yet been merged.
> >
> > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > pin high and thus to light up the display unconditionally.
> >
> > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > ---
> >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> >  1 file changed, 89 insertions(+)
> 
> Hi Heiko,
> 
> Any thoughts about this one? Can we perhaps get it merged for -next?

Does the gpio-backlight work on that device?
That would make the gpioset hack unnecessary.


Heiko



_______________________________________________
Linux-rockchip mailing list
Linux-rockchip@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-rockchip

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Alexey Charkov]

On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
>
> Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > >
> > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > >
> > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > touchscreen is connected over I2C.
> > >
> > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > ---
> > > Note that backlight support is left out for now, as it depends on PWM
> > > support [0] which has not yet been merged.
> > >
> > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > pin high and thus to light up the display unconditionally.
> > >
> > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > ---
> > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > >  1 file changed, 89 insertions(+)
> >
> > Hi Heiko,
> >
> > Any thoughts about this one? Can we perhaps get it merged for -next?
>
> Does the gpio-backlight work on that device?
> That would make the gpioset hack unnecessary.

I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap 
solution, but I don't think it's worth merging upstream, because the 
backlight is supposed to be driven by the hardware PWM on the same pin 
(not bit-banging the GPIO line). After all, Nicolas has been working on 
adding a proper hardware PWM driver for RK3576.

The display itself works without PWM support, and so does the touchscreen.

My temp patch goes like this:

---
  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 15 +++++++++++++++
  1 file changed, 15 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts 
b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
index f20cd6f2c079..5c27fff03569 100644
--- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
@@ -58,6 +58,14 @@ button-vol-up {
  		};
  	};

+	backlight: backlight {
+		compatible = "pwm-backlight";
+		brightness-levels = <20 220>;
+		default-brightness-level = <100>;
+		num-interpolated-steps = <200>;
+		pwms = <&lcd_bl_pwm 0 25000 0>;
+	};
+
  	hdmi-con {
  		compatible = "hdmi-connector";
  		type = "a";
@@ -78,6 +86,12 @@ work_led: led-0 {
  		};
  	};

+	lcd_bl_pwm: pwm {
+		#pwm-cells = <3>;
+		compatible = "pwm-gpio";
+		gpios = <&gpio0 RK_PB5 GPIO_ACTIVE_HIGH>;
+	};
+
  	vbus5v0_typec: regulator-vbus5v0-typec {
  		compatible = "regulator-fixed";
  		regulator-name = "vbus5v0_typec";
@@ -277,6 +291,7 @@ panel@0 {
  		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
  		reg = <0>;

+		backlight = <&backlight>;
  		iovcc-supply = <&vcc3v3_lcd_n>;
  		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
  		vdd-supply = <&vcc3v3_lcd_n>;
-- 

Best regards,
Alexey

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Alexey Charkov]

On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
>
> Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > >
> > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > >
> > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > touchscreen is connected over I2C.
> > >
> > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > ---
> > > Note that backlight support is left out for now, as it depends on PWM
> > > support [0] which has not yet been merged.
> > >
> > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > pin high and thus to light up the display unconditionally.
> > >
> > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > ---
> > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > >  1 file changed, 89 insertions(+)
> >
> > Hi Heiko,
> >
> > Any thoughts about this one? Can we perhaps get it merged for -next?
>
> Does the gpio-backlight work on that device?
> That would make the gpioset hack unnecessary.

I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap 
solution, but I don't think it's worth merging upstream, because the 
backlight is supposed to be driven by the hardware PWM on the same pin 
(not bit-banging the GPIO line). After all, Nicolas has been working on 
adding a proper hardware PWM driver for RK3576.

The display itself works without PWM support, and so does the touchscreen.

My temp patch goes like this:

---
  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 15 +++++++++++++++
  1 file changed, 15 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts 
b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
index f20cd6f2c079..5c27fff03569 100644
--- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
@@ -58,6 +58,14 @@ button-vol-up {
  		};
  	};

+	backlight: backlight {
+		compatible = "pwm-backlight";
+		brightness-levels = <20 220>;
+		default-brightness-level = <100>;
+		num-interpolated-steps = <200>;
+		pwms = <&lcd_bl_pwm 0 25000 0>;
+	};
+
  	hdmi-con {
  		compatible = "hdmi-connector";
  		type = "a";
@@ -78,6 +86,12 @@ work_led: led-0 {
  		};
  	};

+	lcd_bl_pwm: pwm {
+		#pwm-cells = <3>;
+		compatible = "pwm-gpio";
+		gpios = <&gpio0 RK_PB5 GPIO_ACTIVE_HIGH>;
+	};
+
  	vbus5v0_typec: regulator-vbus5v0-typec {
  		compatible = "regulator-fixed";
  		regulator-name = "vbus5v0_typec";
@@ -277,6 +291,7 @@ panel@0 {
  		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
  		reg = <0>;

+		backlight = <&backlight>;
  		iovcc-supply = <&vcc3v3_lcd_n>;
  		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
  		vdd-supply = <&vcc3v3_lcd_n>;
-- 

Best regards,
Alexey

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Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Heiko Stuebner]

Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> 
> On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> >
> > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > >
> > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > >
> > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > touchscreen is connected over I2C.
> > > >
> > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > ---
> > > > Note that backlight support is left out for now, as it depends on PWM
> > > > support [0] which has not yet been merged.
> > > >
> > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > pin high and thus to light up the display unconditionally.
> > > >
> > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > ---
> > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > >  1 file changed, 89 insertions(+)
> > >
> > > Hi Heiko,
> > >
> > > Any thoughts about this one? Can we perhaps get it merged for -next?
> >
> > Does the gpio-backlight work on that device?
> > That would make the gpioset hack unnecessary.
> 
> I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap 
> solution, but I don't think it's worth merging upstream, because the 
> backlight is supposed to be driven by the hardware PWM on the same pin 
> (not bit-banging the GPIO line). After all, Nicolas has been working on 
> adding a proper hardware PWM driver for RK3576.
> 
> The display itself works without PWM support, and so does the touchscreen.

Right now, I don't think we have an actual timeline if/when Nicolas will
be able to work on the pwm again. So my idea was if we want to
integrate the baclight as you described below, to have an actual usable
display and then when the new pwm has landed switch over to that one?


Heiko


> My temp patch goes like this:
> 
> ---
>   arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 15 +++++++++++++++
>   1 file changed, 15 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts 
> b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> index f20cd6f2c079..5c27fff03569 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> @@ -58,6 +58,14 @@ button-vol-up {
>   		};
>   	};
> 
> +	backlight: backlight {
> +		compatible = "pwm-backlight";
> +		brightness-levels = <20 220>;
> +		default-brightness-level = <100>;
> +		num-interpolated-steps = <200>;
> +		pwms = <&lcd_bl_pwm 0 25000 0>;
> +	};
> +
>   	hdmi-con {
>   		compatible = "hdmi-connector";
>   		type = "a";
> @@ -78,6 +86,12 @@ work_led: led-0 {
>   		};
>   	};
> 
> +	lcd_bl_pwm: pwm {
> +		#pwm-cells = <3>;
> +		compatible = "pwm-gpio";
> +		gpios = <&gpio0 RK_PB5 GPIO_ACTIVE_HIGH>;
> +	};
> +
>   	vbus5v0_typec: regulator-vbus5v0-typec {
>   		compatible = "regulator-fixed";
>   		regulator-name = "vbus5v0_typec";
> @@ -277,6 +291,7 @@ panel@0 {
>   		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
>   		reg = <0>;
> 
> +		backlight = <&backlight>;
>   		iovcc-supply = <&vcc3v3_lcd_n>;
>   		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
>   		vdd-supply = <&vcc3v3_lcd_n>;
> 

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Heiko Stuebner]

Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> 
> On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> >
> > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > >
> > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > >
> > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > touchscreen is connected over I2C.
> > > >
> > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > ---
> > > > Note that backlight support is left out for now, as it depends on PWM
> > > > support [0] which has not yet been merged.
> > > >
> > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > pin high and thus to light up the display unconditionally.
> > > >
> > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > ---
> > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > >  1 file changed, 89 insertions(+)
> > >
> > > Hi Heiko,
> > >
> > > Any thoughts about this one? Can we perhaps get it merged for -next?
> >
> > Does the gpio-backlight work on that device?
> > That would make the gpioset hack unnecessary.
> 
> I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap 
> solution, but I don't think it's worth merging upstream, because the 
> backlight is supposed to be driven by the hardware PWM on the same pin 
> (not bit-banging the GPIO line). After all, Nicolas has been working on 
> adding a proper hardware PWM driver for RK3576.
> 
> The display itself works without PWM support, and so does the touchscreen.

Right now, I don't think we have an actual timeline if/when Nicolas will
be able to work on the pwm again. So my idea was if we want to
integrate the baclight as you described below, to have an actual usable
display and then when the new pwm has landed switch over to that one?


Heiko


> My temp patch goes like this:
> 
> ---
>   arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 15 +++++++++++++++
>   1 file changed, 15 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts 
> b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> index f20cd6f2c079..5c27fff03569 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> @@ -58,6 +58,14 @@ button-vol-up {
>   		};
>   	};
> 
> +	backlight: backlight {
> +		compatible = "pwm-backlight";
> +		brightness-levels = <20 220>;
> +		default-brightness-level = <100>;
> +		num-interpolated-steps = <200>;
> +		pwms = <&lcd_bl_pwm 0 25000 0>;
> +	};
> +
>   	hdmi-con {
>   		compatible = "hdmi-connector";
>   		type = "a";
> @@ -78,6 +86,12 @@ work_led: led-0 {
>   		};
>   	};
> 
> +	lcd_bl_pwm: pwm {
> +		#pwm-cells = <3>;
> +		compatible = "pwm-gpio";
> +		gpios = <&gpio0 RK_PB5 GPIO_ACTIVE_HIGH>;
> +	};
> +
>   	vbus5v0_typec: regulator-vbus5v0-typec {
>   		compatible = "regulator-fixed";
>   		regulator-name = "vbus5v0_typec";
> @@ -277,6 +291,7 @@ panel@0 {
>   		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
>   		reg = <0>;
> 
> +		backlight = <&backlight>;
>   		iovcc-supply = <&vcc3v3_lcd_n>;
>   		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
>   		vdd-supply = <&vcc3v3_lcd_n>;
> 





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http://lists.infradead.org/mailman/listinfo/linux-rockchip

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Nicolas Frattaroli]

On Monday, 20 October 2025 14:31:12 Central European Summer Time Heiko Stuebner wrote:
> Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > 
> > On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> > >
> > > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > > >
> > > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > > >
> > > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > > touchscreen is connected over I2C.
> > > > >
> > > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > > ---
> > > > > Note that backlight support is left out for now, as it depends on PWM
> > > > > support [0] which has not yet been merged.
> > > > >
> > > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > > pin high and thus to light up the display unconditionally.
> > > > >
> > > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > > ---
> > > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > > >  1 file changed, 89 insertions(+)
> > > >
> > > > Hi Heiko,
> > > >
> > > > Any thoughts about this one? Can we perhaps get it merged for -next?
> > >
> > > Does the gpio-backlight work on that device?
> > > That would make the gpioset hack unnecessary.
> > 
> > I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap 
> > solution, but I don't think it's worth merging upstream, because the 
> > backlight is supposed to be driven by the hardware PWM on the same pin 
> > (not bit-banging the GPIO line). After all, Nicolas has been working on 
> > adding a proper hardware PWM driver for RK3576.
> > 
> > The display itself works without PWM support, and so does the touchscreen.
> 
> Right now, I don't think we have an actual timeline if/when Nicolas will
> be able to work on the pwm again.

Soon(TM), I've locally reworked the PWM output stuff and core driver
into an MFD. I just need to rework the counter driver now and set up
a proper way to test that the counter works.

I'm hoping to have something next week. If not, then the week after
that.

> So my idea was if we want to
> integrate the baclight as you described below, to have an actual usable
> display and then when the new pwm has landed switch over to that one?

But Heikooooo, DTs should describe hardware, not the lack of Linux
drivers! ;)

For what it's worth, the implementation move to MFD didn't change the
bindings as we don't leak that into the DT at all. If it took any
longer for me to get it done I'd have suggested picking the bindings
and then adding a stub GPIO PWM driver that binds to it as an interim
solution, but it's not worth the ickyness when I'm basically just
a day's work away from having this done.

Kind regards,
Nicolas Frattaroli

> 
> 
> Heiko
> 
> 
> > My temp patch goes like this:
> > 
> > ---
> >   arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 15 +++++++++++++++
> >   1 file changed, 15 insertions(+)
> > 
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts 
> > b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > index f20cd6f2c079..5c27fff03569 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > +++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > @@ -58,6 +58,14 @@ button-vol-up {
> >   		};
> >   	};
> > 
> > +	backlight: backlight {
> > +		compatible = "pwm-backlight";
> > +		brightness-levels = <20 220>;
> > +		default-brightness-level = <100>;
> > +		num-interpolated-steps = <200>;
> > +		pwms = <&lcd_bl_pwm 0 25000 0>;
> > +	};
> > +
> >   	hdmi-con {
> >   		compatible = "hdmi-connector";
> >   		type = "a";
> > @@ -78,6 +86,12 @@ work_led: led-0 {
> >   		};
> >   	};
> > 
> > +	lcd_bl_pwm: pwm {
> > +		#pwm-cells = <3>;
> > +		compatible = "pwm-gpio";
> > +		gpios = <&gpio0 RK_PB5 GPIO_ACTIVE_HIGH>;
> > +	};
> > +
> >   	vbus5v0_typec: regulator-vbus5v0-typec {
> >   		compatible = "regulator-fixed";
> >   		regulator-name = "vbus5v0_typec";
> > @@ -277,6 +291,7 @@ panel@0 {
> >   		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
> >   		reg = <0>;
> > 
> > +		backlight = <&backlight>;
> >   		iovcc-supply = <&vcc3v3_lcd_n>;
> >   		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
> >   		vdd-supply = <&vcc3v3_lcd_n>;
> > 
> 
> 
> 
> 
> 

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Nicolas Frattaroli]

On Monday, 20 October 2025 14:31:12 Central European Summer Time Heiko Stuebner wrote:
> Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > 
> > On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> > >
> > > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > > >
> > > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > > >
> > > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > > touchscreen is connected over I2C.
> > > > >
> > > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > > ---
> > > > > Note that backlight support is left out for now, as it depends on PWM
> > > > > support [0] which has not yet been merged.
> > > > >
> > > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > > pin high and thus to light up the display unconditionally.
> > > > >
> > > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > > ---
> > > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > > >  1 file changed, 89 insertions(+)
> > > >
> > > > Hi Heiko,
> > > >
> > > > Any thoughts about this one? Can we perhaps get it merged for -next?
> > >
> > > Does the gpio-backlight work on that device?
> > > That would make the gpioset hack unnecessary.
> > 
> > I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap 
> > solution, but I don't think it's worth merging upstream, because the 
> > backlight is supposed to be driven by the hardware PWM on the same pin 
> > (not bit-banging the GPIO line). After all, Nicolas has been working on 
> > adding a proper hardware PWM driver for RK3576.
> > 
> > The display itself works without PWM support, and so does the touchscreen.
> 
> Right now, I don't think we have an actual timeline if/when Nicolas will
> be able to work on the pwm again.

Soon(TM), I've locally reworked the PWM output stuff and core driver
into an MFD. I just need to rework the counter driver now and set up
a proper way to test that the counter works.

I'm hoping to have something next week. If not, then the week after
that.

> So my idea was if we want to
> integrate the baclight as you described below, to have an actual usable
> display and then when the new pwm has landed switch over to that one?

But Heikooooo, DTs should describe hardware, not the lack of Linux
drivers! ;)

For what it's worth, the implementation move to MFD didn't change the
bindings as we don't leak that into the DT at all. If it took any
longer for me to get it done I'd have suggested picking the bindings
and then adding a stub GPIO PWM driver that binds to it as an interim
solution, but it's not worth the ickyness when I'm basically just
a day's work away from having this done.

Kind regards,
Nicolas Frattaroli

> 
> 
> Heiko
> 
> 
> > My temp patch goes like this:
> > 
> > ---
> >   arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 15 +++++++++++++++
> >   1 file changed, 15 insertions(+)
> > 
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts 
> > b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > index f20cd6f2c079..5c27fff03569 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > +++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > @@ -58,6 +58,14 @@ button-vol-up {
> >   		};
> >   	};
> > 
> > +	backlight: backlight {
> > +		compatible = "pwm-backlight";
> > +		brightness-levels = <20 220>;
> > +		default-brightness-level = <100>;
> > +		num-interpolated-steps = <200>;
> > +		pwms = <&lcd_bl_pwm 0 25000 0>;
> > +	};
> > +
> >   	hdmi-con {
> >   		compatible = "hdmi-connector";
> >   		type = "a";
> > @@ -78,6 +86,12 @@ work_led: led-0 {
> >   		};
> >   	};
> > 
> > +	lcd_bl_pwm: pwm {
> > +		#pwm-cells = <3>;
> > +		compatible = "pwm-gpio";
> > +		gpios = <&gpio0 RK_PB5 GPIO_ACTIVE_HIGH>;
> > +	};
> > +
> >   	vbus5v0_typec: regulator-vbus5v0-typec {
> >   		compatible = "regulator-fixed";
> >   		regulator-name = "vbus5v0_typec";
> > @@ -277,6 +291,7 @@ panel@0 {
> >   		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
> >   		reg = <0>;
> > 
> > +		backlight = <&backlight>;
> >   		iovcc-supply = <&vcc3v3_lcd_n>;
> >   		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
> >   		vdd-supply = <&vcc3v3_lcd_n>;
> > 
> 
> 
> 
> 
> 





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Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Heiko Stübner]

Am Montag, 20. Oktober 2025, 14:31:12 Mitteleuropäische Sommerzeit schrieb Heiko Stuebner:
> Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > 
> > On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> > >
> > > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > > >
> > > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > > >
> > > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > > touchscreen is connected over I2C.
> > > > >
> > > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > > ---
> > > > > Note that backlight support is left out for now, as it depends on PWM
> > > > > support [0] which has not yet been merged.
> > > > >
> > > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > > pin high and thus to light up the display unconditionally.
> > > > >
> > > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > > ---
> > > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > > >  1 file changed, 89 insertions(+)
> > > >
> > > > Hi Heiko,
> > > >
> > > > Any thoughts about this one? Can we perhaps get it merged for -next?
> > >
> > > Does the gpio-backlight work on that device?
> > > That would make the gpioset hack unnecessary.
> > 
> > I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap 
> > solution, but I don't think it's worth merging upstream, because the 
> > backlight is supposed to be driven by the hardware PWM on the same pin 
> > (not bit-banging the GPIO line). After all, Nicolas has been working on 
> > adding a proper hardware PWM driver for RK3576.
> > 
> > The display itself works without PWM support, and so does the touchscreen.
> 
> Right now, I don't think we have an actual timeline if/when Nicolas will
> be able to work on the pwm again. So my idea was if we want to
> integrate the baclight as you described below, to have an actual usable
> display and then when the new pwm has landed switch over to that one?

With the ELCE around the corner we're nearing the year-mark here ;-)
(And I'm surprised, I remembered this pending patch)

So how about integrating your gpio-pwm backlight for the time being?

Or alternatively just going with a gpio-backlight, like the Anbernic Vita did:

        /*
         * LEDs and Backlights can be controlled as a PWM, but PWM
         * support is not yet available.
         */
        gpio_backlight: backlight {
                compatible = "gpio-backlight";
                gpios = <&gpio2 RK_PC4 GPIO_ACTIVE_HIGH>;
                pinctrl-0 = <&led_backlight_h>;
                pinctrl-names = "default";
        };

DSI without backlight is a quite black screen, which I'd call non-working
still, so would require some form of backlight.


Heiko

> > My temp patch goes like this:
> > 
> > ---
> >   arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 15 +++++++++++++++
> >   1 file changed, 15 insertions(+)
> > 
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts 
> > b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > index f20cd6f2c079..5c27fff03569 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > +++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > @@ -58,6 +58,14 @@ button-vol-up {
> >   		};
> >   	};
> > 
> > +	backlight: backlight {
> > +		compatible = "pwm-backlight";
> > +		brightness-levels = <20 220>;
> > +		default-brightness-level = <100>;
> > +		num-interpolated-steps = <200>;
> > +		pwms = <&lcd_bl_pwm 0 25000 0>;
> > +	};
> > +
> >   	hdmi-con {
> >   		compatible = "hdmi-connector";
> >   		type = "a";
> > @@ -78,6 +86,12 @@ work_led: led-0 {
> >   		};
> >   	};
> > 
> > +	lcd_bl_pwm: pwm {
> > +		#pwm-cells = <3>;
> > +		compatible = "pwm-gpio";
> > +		gpios = <&gpio0 RK_PB5 GPIO_ACTIVE_HIGH>;
> > +	};
> > +
> >   	vbus5v0_typec: regulator-vbus5v0-typec {
> >   		compatible = "regulator-fixed";
> >   		regulator-name = "vbus5v0_typec";
> > @@ -277,6 +291,7 @@ panel@0 {
> >   		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
> >   		reg = <0>;
> > 
> > +		backlight = <&backlight>;
> >   		iovcc-supply = <&vcc3v3_lcd_n>;
> >   		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
> >   		vdd-supply = <&vcc3v3_lcd_n>;
> > 
> 
> 

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Heiko Stübner]

Am Montag, 20. Oktober 2025, 14:31:12 Mitteleuropäische Sommerzeit schrieb Heiko Stuebner:
> Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > 
> > On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> > >
> > > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > > >
> > > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > > >
> > > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > > touchscreen is connected over I2C.
> > > > >
> > > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > > ---
> > > > > Note that backlight support is left out for now, as it depends on PWM
> > > > > support [0] which has not yet been merged.
> > > > >
> > > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > > pin high and thus to light up the display unconditionally.
> > > > >
> > > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > > ---
> > > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > > >  1 file changed, 89 insertions(+)
> > > >
> > > > Hi Heiko,
> > > >
> > > > Any thoughts about this one? Can we perhaps get it merged for -next?
> > >
> > > Does the gpio-backlight work on that device?
> > > That would make the gpioset hack unnecessary.
> > 
> > I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap 
> > solution, but I don't think it's worth merging upstream, because the 
> > backlight is supposed to be driven by the hardware PWM on the same pin 
> > (not bit-banging the GPIO line). After all, Nicolas has been working on 
> > adding a proper hardware PWM driver for RK3576.
> > 
> > The display itself works without PWM support, and so does the touchscreen.
> 
> Right now, I don't think we have an actual timeline if/when Nicolas will
> be able to work on the pwm again. So my idea was if we want to
> integrate the baclight as you described below, to have an actual usable
> display and then when the new pwm has landed switch over to that one?

With the ELCE around the corner we're nearing the year-mark here ;-)
(And I'm surprised, I remembered this pending patch)

So how about integrating your gpio-pwm backlight for the time being?

Or alternatively just going with a gpio-backlight, like the Anbernic Vita did:

        /*
         * LEDs and Backlights can be controlled as a PWM, but PWM
         * support is not yet available.
         */
        gpio_backlight: backlight {
                compatible = "gpio-backlight";
                gpios = <&gpio2 RK_PC4 GPIO_ACTIVE_HIGH>;
                pinctrl-0 = <&led_backlight_h>;
                pinctrl-names = "default";
        };

DSI without backlight is a quite black screen, which I'd call non-working
still, so would require some form of backlight.


Heiko

> > My temp patch goes like this:
> > 
> > ---
> >   arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 15 +++++++++++++++
> >   1 file changed, 15 insertions(+)
> > 
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts 
> > b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > index f20cd6f2c079..5c27fff03569 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > +++ b/arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts
> > @@ -58,6 +58,14 @@ button-vol-up {
> >   		};
> >   	};
> > 
> > +	backlight: backlight {
> > +		compatible = "pwm-backlight";
> > +		brightness-levels = <20 220>;
> > +		default-brightness-level = <100>;
> > +		num-interpolated-steps = <200>;
> > +		pwms = <&lcd_bl_pwm 0 25000 0>;
> > +	};
> > +
> >   	hdmi-con {
> >   		compatible = "hdmi-connector";
> >   		type = "a";
> > @@ -78,6 +86,12 @@ work_led: led-0 {
> >   		};
> >   	};
> > 
> > +	lcd_bl_pwm: pwm {
> > +		#pwm-cells = <3>;
> > +		compatible = "pwm-gpio";
> > +		gpios = <&gpio0 RK_PB5 GPIO_ACTIVE_HIGH>;
> > +	};
> > +
> >   	vbus5v0_typec: regulator-vbus5v0-typec {
> >   		compatible = "regulator-fixed";
> >   		regulator-name = "vbus5v0_typec";
> > @@ -277,6 +291,7 @@ panel@0 {
> >   		compatible = "wanchanglong,w552793baa", "raydium,rm67200";
> >   		reg = <0>;
> > 
> > +		backlight = <&backlight>;
> >   		iovcc-supply = <&vcc3v3_lcd_n>;
> >   		reset-gpios = <&gpio3 RK_PB5 GPIO_ACTIVE_LOW>;
> >   		vdd-supply = <&vcc3v3_lcd_n>;
> > 
> 
> 





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Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Alexey Charkov]

On Wed, Jul 29, 2026 at 6:46 PM Heiko Stübner <heiko@sntech.de> wrote:
>
> Am Montag, 20. Oktober 2025, 14:31:12 Mitteleuropäische Sommerzeit schrieb Heiko Stuebner:
> > Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > >
> > > On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> > > >
> > > > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > > > >
> > > > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > > > >
> > > > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > > > touchscreen is connected over I2C.
> > > > > >
> > > > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > > > ---
> > > > > > Note that backlight support is left out for now, as it depends on PWM
> > > > > > support [0] which has not yet been merged.
> > > > > >
> > > > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > > > pin high and thus to light up the display unconditionally.
> > > > > >
> > > > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > > > ---
> > > > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > > > >  1 file changed, 89 insertions(+)
> > > > >
> > > > > Hi Heiko,
> > > > >
> > > > > Any thoughts about this one? Can we perhaps get it merged for -next?
> > > >
> > > > Does the gpio-backlight work on that device?
> > > > That would make the gpioset hack unnecessary.
> > >
> > > I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap
> > > solution, but I don't think it's worth merging upstream, because the
> > > backlight is supposed to be driven by the hardware PWM on the same pin
> > > (not bit-banging the GPIO line). After all, Nicolas has been working on
> > > adding a proper hardware PWM driver for RK3576.
> > >
> > > The display itself works without PWM support, and so does the touchscreen.
> >
> > Right now, I don't think we have an actual timeline if/when Nicolas will
> > be able to work on the pwm again. So my idea was if we want to
> > integrate the baclight as you described below, to have an actual usable
> > display and then when the new pwm has landed switch over to that one?
>
> With the ELCE around the corner we're nearing the year-mark here ;-)
> (And I'm surprised, I remembered this pending patch)

I've been hoping that Nicolas' PWM series gets further along in the meantime :)

> So how about integrating your gpio-pwm backlight for the time being?

Could do that, but I'm worried if it would immediately become set in
stone because DT is ABI, making it hard to switch to a "proper"
hardware-driven PWM once Nicolas' series lands.

> Or alternatively just going with a gpio-backlight, like the Anbernic Vita did:
>
>         /*
>          * LEDs and Backlights can be controlled as a PWM, but PWM
>          * support is not yet available.
>          */
>         gpio_backlight: backlight {
>                 compatible = "gpio-backlight";
>                 gpios = <&gpio2 RK_PC4 GPIO_ACTIVE_HIGH>;
>                 pinctrl-0 = <&led_backlight_h>;
>                 pinctrl-names = "default";
>         };

In the case of RK3576 EVB1 enabling it at full power is eye-burning
bright, so some sort of PWM is definitely warranted.

Best regards,
Alexey

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Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Alexey Charkov]

On Wed, Jul 29, 2026 at 6:46 PM Heiko Stübner <heiko@sntech.de> wrote:
>
> Am Montag, 20. Oktober 2025, 14:31:12 Mitteleuropäische Sommerzeit schrieb Heiko Stuebner:
> > Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > >
> > > On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> > > >
> > > > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > > > >
> > > > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > > > >
> > > > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > > > touchscreen is connected over I2C.
> > > > > >
> > > > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > > > ---
> > > > > > Note that backlight support is left out for now, as it depends on PWM
> > > > > > support [0] which has not yet been merged.
> > > > > >
> > > > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > > > pin high and thus to light up the display unconditionally.
> > > > > >
> > > > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > > > ---
> > > > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > > > >  1 file changed, 89 insertions(+)
> > > > >
> > > > > Hi Heiko,
> > > > >
> > > > > Any thoughts about this one? Can we perhaps get it merged for -next?
> > > >
> > > > Does the gpio-backlight work on that device?
> > > > That would make the gpioset hack unnecessary.
> > >
> > > I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap
> > > solution, but I don't think it's worth merging upstream, because the
> > > backlight is supposed to be driven by the hardware PWM on the same pin
> > > (not bit-banging the GPIO line). After all, Nicolas has been working on
> > > adding a proper hardware PWM driver for RK3576.
> > >
> > > The display itself works without PWM support, and so does the touchscreen.
> >
> > Right now, I don't think we have an actual timeline if/when Nicolas will
> > be able to work on the pwm again. So my idea was if we want to
> > integrate the baclight as you described below, to have an actual usable
> > display and then when the new pwm has landed switch over to that one?
>
> With the ELCE around the corner we're nearing the year-mark here ;-)
> (And I'm surprised, I remembered this pending patch)

I've been hoping that Nicolas' PWM series gets further along in the meantime :)

> So how about integrating your gpio-pwm backlight for the time being?

Could do that, but I'm worried if it would immediately become set in
stone because DT is ABI, making it hard to switch to a "proper"
hardware-driven PWM once Nicolas' series lands.

> Or alternatively just going with a gpio-backlight, like the Anbernic Vita did:
>
>         /*
>          * LEDs and Backlights can be controlled as a PWM, but PWM
>          * support is not yet available.
>          */
>         gpio_backlight: backlight {
>                 compatible = "gpio-backlight";
>                 gpios = <&gpio2 RK_PC4 GPIO_ACTIVE_HIGH>;
>                 pinctrl-0 = <&led_backlight_h>;
>                 pinctrl-names = "default";
>         };

In the case of RK3576 EVB1 enabling it at full power is eye-burning
bright, so some sort of PWM is definitely warranted.

Best regards,
Alexey

Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Heiko Stübner]

Am Mittwoch, 29. Juli 2026, 18:32:08 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> On Wed, Jul 29, 2026 at 6:46 PM Heiko Stübner <heiko@sntech.de> wrote:
> >
> > Am Montag, 20. Oktober 2025, 14:31:12 Mitteleuropäische Sommerzeit schrieb Heiko Stuebner:
> > > Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > >
> > > > On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> > > > >
> > > > > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > > > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > > > > >
> > > > > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > > > > >
> > > > > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > > > > touchscreen is connected over I2C.
> > > > > > >
> > > > > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > > > > ---
> > > > > > > Note that backlight support is left out for now, as it depends on PWM
> > > > > > > support [0] which has not yet been merged.
> > > > > > >
> > > > > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > > > > pin high and thus to light up the display unconditionally.
> > > > > > >
> > > > > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > > > > ---
> > > > > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > > > > >  1 file changed, 89 insertions(+)
> > > > > >
> > > > > > Hi Heiko,
> > > > > >
> > > > > > Any thoughts about this one? Can we perhaps get it merged for -next?
> > > > >
> > > > > Does the gpio-backlight work on that device?
> > > > > That would make the gpioset hack unnecessary.
> > > >
> > > > I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap
> > > > solution, but I don't think it's worth merging upstream, because the
> > > > backlight is supposed to be driven by the hardware PWM on the same pin
> > > > (not bit-banging the GPIO line). After all, Nicolas has been working on
> > > > adding a proper hardware PWM driver for RK3576.
> > > >
> > > > The display itself works without PWM support, and so does the touchscreen.
> > >
> > > Right now, I don't think we have an actual timeline if/when Nicolas will
> > > be able to work on the pwm again. So my idea was if we want to
> > > integrate the baclight as you described below, to have an actual usable
> > > display and then when the new pwm has landed switch over to that one?
> >
> > With the ELCE around the corner we're nearing the year-mark here ;-)
> > (And I'm surprised, I remembered this pending patch)
> 
> I've been hoping that Nicolas' PWM series gets further along in the meantime :)
> 
> > So how about integrating your gpio-pwm backlight for the time being?
> 
> Could do that, but I'm worried if it would immediately become set in
> stone because DT is ABI, making it hard to switch to a "proper"
> hardware-driven PWM once Nicolas' series lands.

The backlight subsystem is using dev_name() to name the sysfs node.
So if you keep the node name to "backlight", the backlight device stays the
same.

I guess the question is if you also consider the brightness levels as
unchangeable, though I would assume any sane system should just read
max_brightness and adjust accordingly.

Also this is an eval-board ... so you won't have any actual real-world
users :-) .

So, personally I don't see the big hickup here, but we'll do what you
think best.


Heiko

> > Or alternatively just going with a gpio-backlight, like the Anbernic Vita did:
> >
> >         /*
> >          * LEDs and Backlights can be controlled as a PWM, but PWM
> >          * support is not yet available.
> >          */
> >         gpio_backlight: backlight {
> >                 compatible = "gpio-backlight";
> >                 gpios = <&gpio2 RK_PC4 GPIO_ACTIVE_HIGH>;
> >                 pinctrl-0 = <&led_backlight_h>;
> >                 pinctrl-names = "default";
> >         };
> 
> In the case of RK3576 EVB1 enabling it at full power is eye-burning
> bright, so some sort of PWM is definitely warranted.
> 
> Best regards,
> Alexey
> 





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Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1

[Heiko Stübner]

Am Mittwoch, 29. Juli 2026, 18:32:08 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> On Wed, Jul 29, 2026 at 6:46 PM Heiko Stübner <heiko@sntech.de> wrote:
> >
> > Am Montag, 20. Oktober 2025, 14:31:12 Mitteleuropäische Sommerzeit schrieb Heiko Stuebner:
> > > Am Montag, 20. Oktober 2025, 10:50:58 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > >
> > > > On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner <heiko@sntech.de> wrote:
> > > > >
> > > > > Am Montag, 20. Oktober 2025, 10:19:51 Mitteleuropäische Sommerzeit schrieb Alexey Charkov:
> > > > > > On Thu, Sep 25, 2025 at 12:38 AM Alexey Charkov <alchark@gmail.com> wrote:
> > > > > > >
> > > > > > > Add support for the Rockchip W552793DBA-V10 LCD+touchscreen assembly which
> > > > > > > comes physically attached to Rockchip RK3576 EVB1 boards.
> > > > > > >
> > > > > > > The display part is driven by the on-chip MIPI DSI controller, and the
> > > > > > > touchscreen is connected over I2C.
> > > > > > >
> > > > > > > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > > > > > > ---
> > > > > > > Note that backlight support is left out for now, as it depends on PWM
> > > > > > > support [0] which has not yet been merged.
> > > > > > >
> > > > > > > A workaround is simply `gpioset -c 0 13=1` to set the respective GPIO
> > > > > > > pin high and thus to light up the display unconditionally.
> > > > > > >
> > > > > > > [0] https://lore.kernel.org/lkml/20250602-rk3576-pwm-v2-0-a6434b0ce60c@collabora.com/
> > > > > > > ---
> > > > > > >  arch/arm64/boot/dts/rockchip/rk3576-evb1-v10.dts | 89 ++++++++++++++++++++++++
> > > > > > >  1 file changed, 89 insertions(+)
> > > > > >
> > > > > > Hi Heiko,
> > > > > >
> > > > > > Any thoughts about this one? Can we perhaps get it merged for -next?
> > > > >
> > > > > Does the gpio-backlight work on that device?
> > > > > That would make the gpioset hack unnecessary.
> > > >
> > > > I've got a local patch using pwm-gpio and pwm-backlight as a stop-gap
> > > > solution, but I don't think it's worth merging upstream, because the
> > > > backlight is supposed to be driven by the hardware PWM on the same pin
> > > > (not bit-banging the GPIO line). After all, Nicolas has been working on
> > > > adding a proper hardware PWM driver for RK3576.
> > > >
> > > > The display itself works without PWM support, and so does the touchscreen.
> > >
> > > Right now, I don't think we have an actual timeline if/when Nicolas will
> > > be able to work on the pwm again. So my idea was if we want to
> > > integrate the baclight as you described below, to have an actual usable
> > > display and then when the new pwm has landed switch over to that one?
> >
> > With the ELCE around the corner we're nearing the year-mark here ;-)
> > (And I'm surprised, I remembered this pending patch)
> 
> I've been hoping that Nicolas' PWM series gets further along in the meantime :)
> 
> > So how about integrating your gpio-pwm backlight for the time being?
> 
> Could do that, but I'm worried if it would immediately become set in
> stone because DT is ABI, making it hard to switch to a "proper"
> hardware-driven PWM once Nicolas' series lands.

The backlight subsystem is using dev_name() to name the sysfs node.
So if you keep the node name to "backlight", the backlight device stays the
same.

I guess the question is if you also consider the brightness levels as
unchangeable, though I would assume any sane system should just read
max_brightness and adjust accordingly.

Also this is an eval-board ... so you won't have any actual real-world
users :-) .

So, personally I don't see the big hickup here, but we'll do what you
think best.


Heiko

> > Or alternatively just going with a gpio-backlight, like the Anbernic Vita did:
> >
> >         /*
> >          * LEDs and Backlights can be controlled as a PWM, but PWM
> >          * support is not yet available.
> >          */
> >         gpio_backlight: backlight {
> >                 compatible = "gpio-backlight";
> >                 gpios = <&gpio2 RK_PC4 GPIO_ACTIVE_HIGH>;
> >                 pinctrl-0 = <&led_backlight_h>;
> >                 pinctrl-names = "default";
> >         };
> 
> In the case of RK3576 EVB1 enabling it at full power is eye-burning
> bright, so some sort of PWM is definitely warranted.
> 
> Best regards,
> Alexey
>