[PATCH v4 0/2] arm64: qcom: shikra-iqs-evk: Add LT9611UXD HDMI bridge support

[PATCH v4 0/2] arm64: qcom: shikra-iqs-evk: Add LT9611UXD HDMI bridge support

[Mohit Dsor]

Add MDSS display and LT9611UXD DSI-to-HDMI bridge support for the
Shikra IQS EVK, and enable the LT9611C bridge driver in defconfig.

Dependencies:
https://lore.kernel.org/all/20260930-shikra-dt-changes-v5-0-8eaf658a0e38@oss.qualcomm.com/
https://lore.kernel.org/all/20260916-lt9611c-v7-v16-0-c65042fcd245@oss.qualcomm.com/

Changes in v4:
- Rebased on top of next-20260929 (linux-next tag).
- Only two prerequisites remain: the display v5 series and the LT9611C
  driver v16 series, as all other dependencies have since landed in
  linux-next.
- Rename lt9611-specific regulator and pinctrl labels to more generic
  names since these will be shared with other display interfaces in DT
  overlay.
- Link to v3: https://lore.kernel.org/all/20260728-shikra-work-v3-0-e08c322596ac@oss.qualcomm.com/

Changes in v3:
- Remove superfluous comment from pm8150_l11 regulator node.
- Link to v2: https://lore.kernel.org/all/20260717-shikra-work-v2-0-86ae8552259e@oss.qualcomm.com/

Changes in v2:
- Removed port-select property.
- reset and irq is aligned as per driver.
- Rebase on top of shikra-display-v4 series to pass schema check.
- Link to v1 [1/2]: https://lore.kernel.org/lkml/20260627-shikra-dt-changes-v1-5-449a402673d0@oss.qualcomm.com/
- Link to v1 [2/2]: https://lore.kernel.org/lkml/20260618-shikra-work-v1-1-dc30381263f9@oss.qualcomm.com/

prerequisite-message-id: <20260930-shikra-dt-changes-v5-0-8eaf658a0e38@oss.qualcomm.com>
prerequisite-message-id: <20260916-lt9611c-v7-v16-0-c65042fcd245@oss.qualcomm.com>

Signed-off-by: Mohit Dsor <mohit.dsor@oss.qualcomm.com>
base-commit: 6474fa070f2b8013b4b87350b775b8c3be6e8aac
change-id: 20260618-shikra-work-ea756b564b2d
---
Mohit Dsor (2):
      arm64: dts: qcom: shikra-iqs-evk: Add LT9611UXD HDMI bridge support
      arm64: defconfig: Enable LT9611C bridge driver

 arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts | 109 ++++++++++++++++++++++++++++
 arch/arm64/configs/defconfig                |   1 +
 2 files changed, 110 insertions(+)
---
base-commit: fcc65d3aba5059dd1105276e180c624110761d8f
change-id: 20261007-master_lt9611uxd-b0de647ad012

Best regards,
--  
Mohit Dsor <mohit.dsor@oss.qualcomm.com>

[PATCH v4 1/2] arm64: dts: qcom: shikra-iqs-evk: Add LT9611UXD HDMI bridge support

[Mohit Dsor]

Enable the Shikra MDSS display subsystem on the Qualcomm Shikra IQS
EVK board and add the Lontium LT9611UXD DSI-to-HDMI bridge node.

The LT9611UXD is connected via I2C (bus 4, address 0x41), powered by
a GPIO-controlled 3.3V regulator (PM8150 GPIO4) and an always-on 1.8V
rail. Reset is on GPIO76 and interrupt on GPIO85.

The bridge receives DSI output from MDSS and drives an HDMI-A
connector, with the link wired as: DPU -> DSI0 -> LT9611UXD -> HDMI.

Regulator and pinctrl labels use generic board-level names
(vreg_disp_3p3, bridge_irq_pin, bridge_rst_pin) to decouple them
from the bridge chip.

Signed-off-by: Mohit Dsor <mohit.dsor@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts | 109 ++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts b/arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts
index 5df30ad8211f..fee93410b2e4 100644
--- a/arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts
+++ b/arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts
@@ -8,6 +8,7 @@
 #include "shikra-iqs-som.dtsi"
 #include "shikra-evk.dtsi"
 #include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/interrupt-controller/irq.h>
 
 / {
 	model = "Qualcomm Technologies, Inc. Shikra IQS EVK";
@@ -23,6 +24,98 @@ aliases {
 	chosen {
 		stdout-path = "serial0:115200n8";
 	};
+
+	hdmi_connector: hdmi-connector {
+		compatible = "hdmi-connector";
+		type = "a";
+
+		port {
+			hdmi_con: endpoint {
+				remote-endpoint = <&lt9611_out>;
+			};
+		};
+	};
+
+	vreg_disp_3p3: regulator-disp-3p3 {
+		compatible = "regulator-fixed";
+		regulator-name = "vreg_disp_3p3";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		gpio = <&pm8150_gpios 4 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+		pinctrl-0 = <&lcd_bias_en>;
+		pinctrl-names = "default";
+	};
+};
+
+&i2c4 {
+	status = "okay";
+
+	lt9611uxd: lt9611uxd@41 {
+		compatible = "lontium,lt9611uxd";
+		reg = <0x41>;
+		interrupts-extended = <&tlmm 85 IRQ_TYPE_EDGE_FALLING>;
+		reset-gpios = <&tlmm 76 GPIO_ACTIVE_LOW>;
+		vcc-supply = <&vreg_disp_3p3>;
+		vdd-supply = <&pm8150_s4>;
+
+		pinctrl-0 = <&bridge_irq_pin &bridge_rst_pin>;
+		pinctrl-names = "default";
+
+		ports {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			port@0 {
+				reg = <0>;
+
+				lt9611_a: endpoint {
+					remote-endpoint = <&mdss_dsi0_out>;
+				};
+			};
+
+			port@2 {
+				reg = <2>;
+
+				lt9611_out: endpoint {
+					remote-endpoint = <&hdmi_con>;
+				};
+			};
+		};
+	};
+};
+
+&mdss {
+	status = "okay";
+};
+
+&mdss_dsi0 {
+	vdda-supply = <&pm8150_l11>;
+
+	status = "okay";
+};
+
+&mdss_dsi0_out {
+	remote-endpoint = <&lt9611_a>;
+	data-lanes = <0 1 2 3>;
+};
+
+&mdss_dsi0_phy {
+	status = "okay";
+};
+
+&pm8150_gpios {
+	lcd_bias_en: lcd-bias-en-state {
+		pins = "gpio4";
+		function = PMIC_GPIO_FUNC_NORMAL;
+		bias-disable;
+	};
+};
+
+&pm8150_l11 {
+	regulator-min-microvolt = <1232000>;
+	regulator-max-microvolt = <1232000>;
+	regulator-allow-set-load;
 };
 
 &remoteproc_cdsp {
@@ -67,6 +160,22 @@ &sdhc_2 {
 	status = "okay";
 };
 
+&tlmm {
+	bridge_irq_pin: bridge-irq-state {
+		pins = "gpio85";
+		function = "gpio";
+		drive-strength = <2>;
+		bias-disable;
+	};
+
+	bridge_rst_pin: bridge-rst-state {
+		pins = "gpio76";
+		function = "gpio";
+		drive-strength = <8>;
+		bias-disable;
+	};
+};
+
 &usb_1_hsphy {
 	vdd-supply = <&pm8150_l4>;
 	vdda-pll-supply = <&pm8150_l12>;

-- 
2.34.1

Re: [PATCH v4 1/2] arm64: dts: qcom: shikra-iqs-evk: Add LT9611UXD HDMI bridge support

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] dts: Invalid compatible 'lontium,lt9611uxd' lacks driver support
- [High] dts: Incorrect reset-gpios polarity holds LT9611 bridge in reset
--

commit d181c75b1ca5c7813638aeaae19d81602f7108ef
Author: Mohit Dsor <mohit.dsor@oss.qualcomm.com>

arm64: dts: qcom: shikra-iqs-evk: Add LT9611UXD HDMI bridge support

Enable the Shikra MDSS display subsystem on the Qualcomm Shikra IQS
EVK board and add the Lontium LT9611UXD DSI-to-HDMI bridge node.

> diff --git a/arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts b/arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts
> index 5df30ad8211f8..fee93410b2e43 100644
> --- a/arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts
> +++ b/arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts
[ ... ]
> @@ -23,6 +24,98 @@ aliases {
[ ... ]
> +&i2c4 {
> +	status = "okay";
> +
> +	lt9611uxd: lt9611uxd@41 {
> +		compatible = "lontium,lt9611uxd";

[Severity: High]
Does this compatible string have a corresponding driver implementation and DT
binding?

There is no of_device_id match for "lontium,lt9611uxd" in any driver in the
kernel (the Lontium bridge drivers in drivers/gpu/drm/bridge/ only support
"lontium,lt9611" and "lontium,lt9611uxc"), nor is there an associated DT
binding. Because no driver will bind to this node, the display output will
silently fail to initialize.

> +		reg = <0x41>;
> +		interrupts-extended = <&tlmm 85 IRQ_TYPE_EDGE_FALLING>;
> +		reset-gpios = <&tlmm 76 GPIO_ACTIVE_LOW>;

[Severity: High]
Does this reset polarity interact correctly with the driver's hardcoded reset
sequence?

The existing Lontium bridge drivers (lt9611 and lt9611uxc) are implemented
with an inverted reset sequence. They call
gpiod_set_value_cansleep(reset_gpio, 1) at the end of their reset routine
(lt9611_reset()) to take the device out of reset, assuming the DT specifies
GPIO_ACTIVE_HIGH as a workaround.

When GPIO_ACTIVE_LOW is used instead, the gpiolib subsystem translates the
logical 1 to a physical 0 (LOW). This will drive the reset pin physically LOW
at the end of initialization, trapping the bridge in reset indefinitely and
causing probe failures and I2C communication timeouts.

> +		vcc-supply = <&vreg_disp_3p3>;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261007-master_lt9611uxd-v4-0-9986704e2a7b@oss.qualcomm.com?part=1

Re: [PATCH v4 1/2] arm64: dts: qcom: shikra-iqs-evk: Add LT9611UXD HDMI bridge support

[Dmitry Baryshkov]

On Wed, Oct 07, 2026 at 06:21:06PM +0530, Mohit Dsor wrote:
> Enable the Shikra MDSS display subsystem on the Qualcomm Shikra IQS
> EVK board and add the Lontium LT9611UXD DSI-to-HDMI bridge node.
> 
> The LT9611UXD is connected via I2C (bus 4, address 0x41), powered by
> a GPIO-controlled 3.3V regulator (PM8150 GPIO4) and an always-on 1.8V
> rail. Reset is on GPIO76 and interrupt on GPIO85.
> 
> The bridge receives DSI output from MDSS and drives an HDMI-A
> connector, with the link wired as: DPU -> DSI0 -> LT9611UXD -> HDMI.
> 
> Regulator and pinctrl labels use generic board-level names
> (vreg_disp_3p3, bridge_irq_pin, bridge_rst_pin) to decouple them
> from the bridge chip.
> 
> Signed-off-by: Mohit Dsor <mohit.dsor@oss.qualcomm.com>
> ---
>  arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts | 109 ++++++++++++++++++++++++++++
>  1 file changed, 109 insertions(+)
> 
> +
> +&i2c4 {
> +	status = "okay";
> +
> +	lt9611uxd: lt9611uxd@41 {

unused label. rename the node to hdmi-bridge

> +		compatible = "lontium,lt9611uxd";
> +		reg = <0x41>;
> +		interrupts-extended = <&tlmm 85 IRQ_TYPE_EDGE_FALLING>;
> +		reset-gpios = <&tlmm 76 GPIO_ACTIVE_LOW>;
> +		vcc-supply = <&vreg_disp_3p3>;
> +		vdd-supply = <&pm8150_s4>;
> +
> +		pinctrl-0 = <&bridge_irq_pin &bridge_rst_pin>;
> +		pinctrl-names = "default";
> +
> +		ports {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +
> +			port@0 {
> +				reg = <0>;
> +
> +				lt9611_a: endpoint {
> +					remote-endpoint = <&mdss_dsi0_out>;
> +				};
> +			};
> +
> +			port@2 {
> +				reg = <2>;
> +
> +				lt9611_out: endpoint {
> +					remote-endpoint = <&hdmi_con>;

hdmi_connector_out

> +				};
> +			};
> +		};
> +	};
> +};
> +
> @@ -67,6 +160,22 @@ &sdhc_2 {
>  	status = "okay";
>  };
>  
> +&tlmm {
> +	bridge_irq_pin: bridge-irq-state {
> +		pins = "gpio85";
> +		function = "gpio";
> +		drive-strength = <2>;
> +		bias-disable;
> +	};
> +
> +	bridge_rst_pin: bridge-rst-state {

I think the current recommendation is to sort them by the pin number.

> +		pins = "gpio76";
> +		function = "gpio";
> +		drive-strength = <8>;
> +		bias-disable;
> +	};
> +};
> +
>  &usb_1_hsphy {
>  	vdd-supply = <&pm8150_l4>;
>  	vdda-pll-supply = <&pm8150_l12>;
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry

Re: [PATCH v4 1/2] arm64: dts: qcom: shikra-iqs-evk: Add LT9611UXD HDMI bridge support

[Mohit Dsor]

On Wed, Oct 07, 2026 at 04:40:26PM +0300, Dmitry Baryshkov wrote:
> On Wed, Oct 07, 2026 at 06:21:06PM +0530, Mohit Dsor wrote:
> > Enable the Shikra MDSS display subsystem on the Qualcomm Shikra IQS
> > EVK board and add the Lontium LT9611UXD DSI-to-HDMI bridge node.
> > 
> > The LT9611UXD is connected via I2C (bus 4, address 0x41), powered by
> > a GPIO-controlled 3.3V regulator (PM8150 GPIO4) and an always-on 1.8V
> > rail. Reset is on GPIO76 and interrupt on GPIO85.
> > 
> > The bridge receives DSI output from MDSS and drives an HDMI-A
> > connector, with the link wired as: DPU -> DSI0 -> LT9611UXD -> HDMI.
> > 
> > Regulator and pinctrl labels use generic board-level names
> > (vreg_disp_3p3, bridge_irq_pin, bridge_rst_pin) to decouple them
> > from the bridge chip.
> > 
> > Signed-off-by: Mohit Dsor <mohit.dsor@oss.qualcomm.com>
> > ---
> >  arch/arm64/boot/dts/qcom/shikra-iqs-evk.dts | 109 ++++++++++++++++++++++++++++
> >  1 file changed, 109 insertions(+)
> > 
> > +
> > +&i2c4 {
> > +	status = "okay";
> > +
> > +	lt9611uxd: lt9611uxd@41 {
> 
> unused label. rename the node to hdmi-bridge
The label will be required in overlays on top of HDMI so shall we remove it now or add in overlay series ?
> 
> > +		compatible = "lontium,lt9611uxd";
> > +		reg = <0x41>;
> > +		interrupts-extended = <&tlmm 85 IRQ_TYPE_EDGE_FALLING>;
> > +		reset-gpios = <&tlmm 76 GPIO_ACTIVE_LOW>;
> > +		vcc-supply = <&vreg_disp_3p3>;
> > +		vdd-supply = <&pm8150_s4>;
> > +
> > +		pinctrl-0 = <&bridge_irq_pin &bridge_rst_pin>;
> > +		pinctrl-names = "default";
> > +
> > +		ports {
> > +			#address-cells = <1>;
> > +			#size-cells = <0>;
> > +
> > +			port@0 {
> > +				reg = <0>;
> > +
> > +				lt9611_a: endpoint {
> > +					remote-endpoint = <&mdss_dsi0_out>;
> > +				};
> > +			};
> > +
> > +			port@2 {
> > +				reg = <2>;
> > +
> > +				lt9611_out: endpoint {
> > +					remote-endpoint = <&hdmi_con>;
> 
> hdmi_connector_out
Will fix it in next version.
> 
> > +				};
> > +			};
> > +		};
> > +	};
> > +};
> > +
> > @@ -67,6 +160,22 @@ &sdhc_2 {
> >  	status = "okay";
> >  };
> >  
> > +&tlmm {
> > +	bridge_irq_pin: bridge-irq-state {
> > +		pins = "gpio85";
> > +		function = "gpio";
> > +		drive-strength = <2>;
> > +		bias-disable;
> > +	};
> > +
> > +	bridge_rst_pin: bridge-rst-state {
> 
> I think the current recommendation is to sort them by the pin number.
Sure, will sort it accordingly.
> 
> > +		pins = "gpio76";
> > +		function = "gpio";
> > +		drive-strength = <8>;
> > +		bias-disable;
> > +	};
> > +};
> > +
> >  &usb_1_hsphy {
> >  	vdd-supply = <&pm8150_l4>;
> >  	vdda-pll-supply = <&pm8150_l12>;
> > 
> > -- 
> > 2.34.1
> > 
> 
> -- 
> With best wishes
> Dmitry

[PATCH v4 2/2] arm64: defconfig: Enable LT9611C bridge driver

[Mohit Dsor]

Enable the Lontium LT9611C DSI-to-HDMI bridge driver as a module.
This driver supports the LT9611UXD chip used on the Shikra IQS EVK
board to provide HDMI output via the MDSS DSI interface.

Signed-off-by: Mohit Dsor <mohit.dsor@oss.qualcomm.com>
---
 arch/arm64/configs/defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index 65fcbbfc1601..d18f72e55330 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -977,6 +977,7 @@ CONFIG_DRM_I2C_NXP_TDA998X=m
 CONFIG_DRM_ITE_IT6263=m
 CONFIG_DRM_LONTIUM_LT8912B=m
 CONFIG_DRM_LONTIUM_LT9611=m
+CONFIG_DRM_LONTIUM_LT9611C=m
 CONFIG_DRM_LONTIUM_LT9611UXC=m
 CONFIG_DRM_LONTIUM_LT8713SX=m
 CONFIG_DRM_ITE_IT66121=m

-- 
2.34.1

Re: [PATCH v4 2/2] arm64: defconfig: Enable LT9611C bridge driver

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] arm64: undefined CONFIG_DRM_LONTIUM_LT9611C added to defconfig
--

commit d7fcead75041287b78534a901e1cd8e93f2636d2
Author: Mohit Dsor <mohit.dsor@oss.qualcomm.com>

arm64: defconfig: Enable LT9611C bridge driver
    
Enable the Lontium LT9611C DSI-to-HDMI bridge driver as a module.
This driver supports the LT9611UXD chip used on the Shikra IQS EVK
board to provide HDMI output via the MDSS DSI interface.

> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> index fce418fe6ff65..b4be8ec8d4c86 100644
> --- a/arch/arm64/configs/defconfig
> +++ b/arch/arm64/configs/defconfig
> @@ -977,6 +977,7 @@ CONFIG_DRM_I2C_NXP_TDA998X=m
>  CONFIG_DRM_ITE_IT6263=m
>  CONFIG_DRM_LONTIUM_LT8912B=m
>  CONFIG_DRM_LONTIUM_LT9611=m
> +CONFIG_DRM_LONTIUM_LT9611C=m

[Severity: Low]
Is this the intended Kconfig symbol?

The symbol CONFIG_DRM_LONTIUM_LT9611C is undefined in the Kconfig system.
Adding an undefined symbol to defconfig acts as a no-op, and the build system
will silently drop it during the build process.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261007-master_lt9611uxd-v4-0-9986704e2a7b@oss.qualcomm.com?part=2

Re: [PATCH v4 2/2] arm64: defconfig: Enable LT9611C bridge driver

[Dmitry Baryshkov]

On Wed, Oct 07, 2026 at 06:21:07PM +0530, Mohit Dsor wrote:
> Enable the Lontium LT9611C DSI-to-HDMI bridge driver as a module.
> This driver supports the LT9611UXD chip used on the Shikra IQS EVK
> board to provide HDMI output via the MDSS DSI interface.


Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


> 
> Signed-off-by: Mohit Dsor <mohit.dsor@oss.qualcomm.com>
> ---
>  arch/arm64/configs/defconfig | 1 +
>  1 file changed, 1 insertion(+)
> 

-- 
With best wishes
Dmitry

Re: [PATCH v4 2/2] arm64: defconfig: Enable LT9611C bridge driver

[Krzysztof Kozlowski]

On 07/10/2026 14:51, Mohit Dsor wrote:
> Enable the Lontium LT9611C DSI-to-HDMI bridge driver as a module.
> This driver supports the LT9611UXD chip used on the Shikra IQS EVK
> board to provide HDMI output via the MDSS DSI interface.

Same feedback as v1. Why every second defconfig patch from Qualcomm
completely ignores the fact that this is not a Qualcomm-only or
Qualcomm-specific defconfig?

Best regards,
Krzysztof

Re: [PATCH v4 2/2] arm64: defconfig: Enable LT9611C bridge driver

[Mohit Dsor]

On Fri, Oct 09, 2026 at 01:50:39PM +0200, Krzysztof Kozlowski wrote:
> On 07/10/2026 14:51, Mohit Dsor wrote:
> > Enable the Lontium LT9611C DSI-to-HDMI bridge driver as a module.
> > This driver supports the LT9611UXD chip used on the Shikra IQS EVK
> > board to provide HDMI output via the MDSS DSI interface.
> 
> Same feedback as v1. Why every second defconfig patch from Qualcomm
> completely ignores the fact that this is not a Qualcomm-only or
> Qualcomm-specific defconfig?
Sure, will change commit message accordingly.
> 
> Best regards,
> Krzysztof