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([2001:8f8:183b:9829:50b9:dafe:ddca:3ba4]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4710f29b559sm104370685e9.8.2025.10.20.01.50.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Oct 2025 01:50:59 -0700 (PDT) Message-ID: <748fd61a-31fb-436f-b028-b47807a4860c@gmail.com> Date: Mon, 20 Oct 2025 12:50:58 +0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Alexey Charkov Subject: Re: [PATCH] arm64: dts: rockchip: Add DSI LCD display on rk3576-evb1 To: Heiko Stuebner Cc: Rob Herring , Krzysztof Kozlowski , Conor Dooley , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org References: <20250925-rk3576-evb1-dsi-v1-1-c76fc3740abc@gmail.com> <5143458.iZASKD2KPV@phil> Content-Language: en-US In-Reply-To: <5143458.iZASKD2KPV@phil> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On Mon, Oct 20, 2025 at 12:31 PM Heiko Stuebner 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 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 > > > --- > > > 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