[PATCH 0/4] drm/panel: himax-hx8279: add VDDP supply for Startek KD070FHFID078

[PATCH 0/4] drm/panel: himax-hx8279: add VDDP supply for Startek KD070FHFID078

[David Lechner]

The Startek KD070FHFID078 panel has a VDDP power input, which feeds its
DC-DC converter in addition to VDD and IOVCC. On the MediaTek Genio 520
and 720 EVKs, VDDP is switched by its own regulator, and on the Genio
1200 EVK it comes from its own PMIC LDO, so it needs to be described and
enabled. The existing Genio 1200 EVK device tree also turned out to
describe the panel supplies incorrectly, so this series fixes that too.

Patch 1 adds vddp-supply to the binding, required for the Startek panel
only, since it is not known whether the Aoly panel has a VDDP input.
Patch 2 enables the new supply in the driver. Boards without a
vddp-supply in their device tree get a dummy regulator and keep working
so nothing breaks.

Patch 3 adds the property to the Genio 510 and 700 EVK device trees,
where VDDP and VDD share the same VSYS_LCM1 rail. Patch 4 fixes the
panel supplies on the Genio 1200 EVK: its device tree pointed vdd-supply
at the VDDP rail and used the backlight (VDD) switch as the IOVCC
regulator.

The Genio 520 and 720 EVK device trees are not upstream yet; U-Boot
support for them is being submitted separately and uses this property.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
David Lechner (4):
      dt-bindings: display: panel: himax,hx8279: add vddp-supply
      drm/panel: himax-hx8279: add the VDDP supply
      arm64: dts: mediatek: mt8390-genio-common: add the panel vddp-supply
      arm64: dts: mediatek: mt8395-genio-common: fix the panel supplies

 .../bindings/display/panel/himax,hx8279.yaml        | 13 +++++++++++++
 .../boot/dts/mediatek/mt8390-genio-common.dtsi      |  1 +
 .../boot/dts/mediatek/mt8395-genio-common.dtsi      | 21 ++++++++-------------
 drivers/gpu/drm/panel/panel-himax-hx8279.c          |  3 ++-
 4 files changed, 24 insertions(+), 14 deletions(-)
---
base-commit: 5d7b464a4f517d1db533b1b231f42ddcf4e1dff4
change-id: 20261006-panel-himax-hx8279-vddp-5dabebff2c99

Best regards,
--  
David Lechner <dlechner@baylibre.com>

[PATCH 1/4] dt-bindings: display: panel: himax,hx8279: add vddp-supply

[David Lechner]

Add a vddp-supply property and make it required for the Startek
KD070FHFID078 panel.

The Startek KD070FHFID078 panel has a separate VDDP power input, which
feeds its DC-DC converter, in addition to VDD and IOVCC. On the MediaTek
Genio 520 and 720 EVKs, VDDP is switched by its own GPIO-controlled
regulator, and on the Genio 1200 EVK it comes from its own PMIC LDO.
In both cases it is separate from the other two supplies, so it needs to
be described to power the panel.

Making it required means existing device trees with this panel without
it no longer validate. This is ok since the Linux driver will still work
with them because the regulator core uses a dummy regulator for any
missing supply. And anyone who sees the warning about the missing
supply should add it to their device tree.

It stays optional for the Aoly SL101PM1794FOG-V15 panel, as it is not
known whether that panel has a VDDP input.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
 .../devicetree/bindings/display/panel/himax,hx8279.yaml     | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/panel/himax,hx8279.yaml b/Documentation/devicetree/bindings/display/panel/himax,hx8279.yaml
index f619aea82bdf..c79056c39037 100644
--- a/Documentation/devicetree/bindings/display/panel/himax,hx8279.yaml
+++ b/Documentation/devicetree/bindings/display/panel/himax,hx8279.yaml
@@ -37,6 +37,9 @@ properties:
   vdd-supply:
     description: Panel power supply
 
+  vddp-supply:
+    description: Panel DC-DC converter power supply (VDDP)
+
 required:
   - compatible
   - reg
@@ -45,6 +48,15 @@ required:
   - iovcc-supply
   - vdd-supply
 
+if:
+  properties:
+    compatible:
+      contains:
+        const: startek,kd070fhfid078
+then:
+  required:
+    - vddp-supply
+
 unevaluatedProperties: false
 
 examples:
@@ -63,6 +75,7 @@ examples:
             reset-gpios = <&pio 45 GPIO_ACTIVE_HIGH>;
             iovcc-supply = <&vreg_lcm_vio>;
             vdd-supply = <&vreg_lcm_vdd>;
+            vddp-supply = <&vreg_lcm_vddp>;
 
             port {
                 panel_in: endpoint {

-- 
2.53.0

Re: [PATCH 1/4] dt-bindings: display: panel: himax,hx8279: add vddp-supply

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 1106 bytes --]

On Tue, Oct 06, 2026 at 03:25:01PM -0500, David Lechner wrote:
> Add a vddp-supply property and make it required for the Startek
> KD070FHFID078 panel.
> 
> The Startek KD070FHFID078 panel has a separate VDDP power input, which
> feeds its DC-DC converter, in addition to VDD and IOVCC. On the MediaTek
> Genio 520 and 720 EVKs, VDDP is switched by its own GPIO-controlled
> regulator, and on the Genio 1200 EVK it comes from its own PMIC LDO.
> In both cases it is separate from the other two supplies, so it needs to
> be described to power the panel.
> 
> Making it required means existing device trees with this panel without
> it no longer validate. This is ok since the Linux driver will still work
> with them because the regulator core uses a dummy regulator for any
> missing supply. And anyone who sees the warning about the missing
> supply should add it to their device tree.
> 
> It stays optional for the Aoly SL101PM1794FOG-V15 panel, as it is not
> known whether that panel has a VDDP input.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
pw-bot: not-applicable

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[PATCH 2/4] drm/panel: himax-hx8279: add the VDDP supply

[David Lechner]

Get and enable the vddp-supply along with VDD and IOVCC.

The Startek KD070FHFID078 panel has a VDDP power input, which the
MediaTek Genio 520 and 720 EVKs switch with a regulator of its own, so
the driver has to enable it for the panel to be powered on those boards.

On boards that do not describe vddp-supply, the regulator core provides
a dummy regulator, so they only see a "using dummy regulator" message.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
 drivers/gpu/drm/panel/panel-himax-hx8279.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-himax-hx8279.c b/drivers/gpu/drm/panel/panel-himax-hx8279.c
index 9e443c719843..fe665cd3a3d2 100644
--- a/drivers/gpu/drm/panel/panel-himax-hx8279.c
+++ b/drivers/gpu/drm/panel/panel-himax-hx8279.c
@@ -112,7 +112,7 @@
 struct hx8279 {
 	struct drm_panel panel;
 	struct mipi_dsi_device *dsi[2];
-	struct regulator_bulk_data vregs[2];
+	struct regulator_bulk_data vregs[3];
 	struct gpio_desc *enable_gpio;
 	struct gpio_desc *reset_gpio;
 	const struct hx8279_panel_desc *desc;
@@ -769,6 +769,7 @@ static int hx8279_init_vregs(struct hx8279 *hx, struct device *dev)
 
 	hx->vregs[0].supply = "vdd";
 	hx->vregs[1].supply = "iovcc";
+	hx->vregs[2].supply = "vddp";
 	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(hx->vregs),
 				      hx->vregs);
 	if (ret < 0)

-- 
2.53.0

[PATCH 3/4] arm64: dts: mediatek: mt8390-genio-common: add the panel vddp-supply

[David Lechner]

Add the vddp-supply of the Startek KD070FHFID078 panel, now required by
the himax,hx8279 binding.

On the Genio 510 and 700 EVKs, the panel's VDDP input is on the always-on
vsys_lcm1 rail, the regulator that vdd-supply already points at.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
 arch/arm64/boot/dts/mediatek/mt8390-genio-common.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/mediatek/mt8390-genio-common.dtsi b/arch/arm64/boot/dts/mediatek/mt8390-genio-common.dtsi
index 669eaec662f3..449af8014769 100644
--- a/arch/arm64/boot/dts/mediatek/mt8390-genio-common.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8390-genio-common.dtsi
@@ -324,6 +324,7 @@ panel@0 {
 		reset-gpios = <&pio 25 GPIO_ACTIVE_HIGH>;
 		iovcc-supply = <&lcm1_iovcc>;
 		vdd-supply = <&lcm1_vddp>;
+		vddp-supply = <&lcm1_vddp>;
 		pinctrl-names = "default";
 		pinctrl-0 = <&panel_default_pins>;
 

-- 
2.53.0

[PATCH 4/4] arm64: dts: mediatek: mt8395-genio-common: fix the panel supplies

[David Lechner]

Point each supply of the Startek KD070FHFID078 panel at the rail that
feeds it on the Genio 1200 EVK, and add the vddp-supply that the
himax,hx8279 binding now requires.

The Genio 1200 EVK is wired as follows:
- VDD (backlight LED power) comes from VSYS through a switch enabled by
  GPIO47. That is the regulator previously described as lcm0_iovcc, so
  rename it to lcm0_vdd and feed it from VSYS.
- IOVCC comes directly from MT6360 LDO2.
- VDDP comes directly from MT6360 LDO1. The lcm0_vddp regulator only
  passed LDO1 through, so drop it.

The previous description pointed vdd-supply at the VDDP rail and used
the VDD switch as the IOVCC regulator. It worked only because the driver
enables all the supplies together.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
 .../boot/dts/mediatek/mt8395-genio-common.dtsi      | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/boot/dts/mediatek/mt8395-genio-common.dtsi b/arch/arm64/boot/dts/mediatek/mt8395-genio-common.dtsi
index aef908df530e..f415b6f71653 100644
--- a/arch/arm64/boot/dts/mediatek/mt8395-genio-common.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8395-genio-common.dtsi
@@ -175,22 +175,16 @@ button-volume-up {
 		};
 	};
 
-	lcm0_iovcc: regulator-vio18-lcm0 {
+	lcm0_vdd: regulator-vsys-lcm0 {
 		compatible = "regulator-fixed";
-		regulator-name = "vio18_lcm0";
+		regulator-name = "vsys_lcm0";
+		regulator-min-microvolt = <4200000>;
+		regulator-max-microvolt = <4200000>;
 		enable-active-high;
 		gpio = <&pio 47 GPIO_ACTIVE_HIGH>;
 		pinctrl-names = "default";
 		pinctrl-0 = <&dsi0_vreg_en_pins>;
-		vin-supply = <&mt6360_ldo2>;
-	};
-
-	lcm0_vddp: regulator-vsys-lcm0 {
-		compatible = "regulator-fixed";
-		regulator-name = "vsys_lcm0";
-		regulator-always-on;
-		regulator-boot-on;
-		vin-supply = <&mt6360_ldo1>;
+		vin-supply = <&reg_vsys>;
 	};
 
 	wifi_fixed_3v3: regulator-2 {
@@ -303,8 +297,9 @@ panel@0 {
 		backlight = <&backlight_lcm0>;
 		enable-gpios = <&pio 48 GPIO_ACTIVE_HIGH>;
 		reset-gpios = <&pio 108 GPIO_ACTIVE_HIGH>;
-		iovcc-supply = <&lcm0_iovcc>;
-		vdd-supply = <&lcm0_vddp>;
+		iovcc-supply = <&mt6360_ldo2>;
+		vdd-supply = <&lcm0_vdd>;
+		vddp-supply = <&mt6360_ldo1>;
 		pinctrl-names = "default";
 		pinctrl-0 = <&panel_default_pins>;
 

-- 
2.53.0