[PATCH 0/3] Add support for the Leadtek LTK028QV25BYL display panel

[PATCH 0/3] Add support for the Leadtek LTK028QV25BYL display panel

[Herve Codina]

Hi,

The Leadtek LTK08QV25BYL is a 2.8" 240x320 DSI display.

This series adds support for this device.

Best regards,
Hervé

Herve Codina (3):
  dt-bindings: display: panel: Add the Leadtek LTK08QV25BYL panel
  drm/panel: Add support for the Leadtek LTK08QV25BYL panel
  MAINTAINERS: Add the Leadtek LTK028QV25BYL panel driver entry

 .../display/panel/leadtek,ltk028qv25byl.yaml  |  55 ++++
 MAINTAINERS                                   |   7 +
 drivers/gpu/drm/panel/Kconfig                 |  12 +
 drivers/gpu/drm/panel/Makefile                |   1 +
 .../drm/panel/panel-leadtek-ltk028qv25byl.c   | 304 ++++++++++++++++++
 5 files changed, 379 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/panel/leadtek,ltk028qv25byl.yaml
 create mode 100644 drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c

-- 
2.51.0

[PATCH 1/3] dt-bindings: display: panel: Add the Leadtek LTK08QV25BYL panel

[Herve Codina]

The Leadtek LTK08QV25BYL is a 2.8" 240x320 DSI display.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
---
 .../display/panel/leadtek,ltk028qv25byl.yaml  | 55 +++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/panel/leadtek,ltk028qv25byl.yaml

diff --git a/Documentation/devicetree/bindings/display/panel/leadtek,ltk028qv25byl.yaml b/Documentation/devicetree/bindings/display/panel/leadtek,ltk028qv25byl.yaml
new file mode 100644
index 000000000000..c10365984057
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/panel/leadtek,ltk028qv25byl.yaml
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/leadtek,ltk028qv25byl.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Leadtek LTK028QV25BYL 2.8in 240x320 DSI panel
+
+maintainers:
+  - Herve Codina <herve.codina@bootlin.com>
+
+allOf:
+  - $ref: panel-common.yaml#
+
+properties:
+  compatible:
+    const: leadtek,ltk028qv25byl
+
+  reg:
+    maxItems: 1
+
+  backlight: true
+  port: true
+  reset-gpios: true
+
+  iovcc-supply:
+    description: regulator that supplies the IOVCC voltage
+
+  vci-supply:
+    description: regulator that supplies the VCI voltage
+
+required:
+  - compatible
+  - reg
+  - backlight
+  - iovcc-supply
+  - vci-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    dsi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        panel@0 {
+            compatible = "leadtek,ltk028qv25byl";
+            reg = <0>;
+            backlight = <&backlight>;
+            iovcc-supply = <&vcc_1v8>;
+            vci-supply = <&vcc3v3_lcd>;
+        };
+    };
+
+...
-- 
2.51.0

[PATCH 2/3] drm/panel: Add support for the Leadtek LTK08QV25BYL panel

[Herve Codina]

The Leadtek LTK08QV25BYL is a 2.8" 240x320 DSI display.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
---
 drivers/gpu/drm/panel/Kconfig                 |  12 +
 drivers/gpu/drm/panel/Makefile                |   1 +
 .../drm/panel/panel-leadtek-ltk028qv25byl.c   | 304 ++++++++++++++++++
 3 files changed, 317 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 407c5f6a268b..faa417195b6e 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -367,6 +367,18 @@ config DRM_PANEL_KINGDISPLAY_KD097D04
 	  24 bit RGB per pixel. It provides a MIPI DSI interface to
 	  the host and has a built-in LED backlight.
 
+config DRM_PANEL_LEADTEK_LTK028QV25BYL
+	tristate "Leadtek LTK028QV25BYL panel"
+	depends on OF
+	depends on DRM_MIPI_DSI
+	depends on BACKLIGHT_CLASS_DEVICE
+	help
+	  Say Y here if you want to enable support for Leadtek LTK028QV25BYL
+	  TFT-LCD modules. The panel has a 240x320 resolution and uses
+	  18 bit RGB per pixel. It provides a MIPI DSI interface to
+	  the host and has a built-in LED backlight.
+
+
 config DRM_PANEL_LEADTEK_LTK050H3146W
 	tristate "Leadtek LTK050H3146W panel"
 	depends on OF
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index 3615a761b44f..12073c34e0f5 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_DRM_PANEL_JDI_LPM102A188A) += panel-jdi-lpm102a188a.o
 obj-$(CONFIG_DRM_PANEL_JDI_R63452) += panel-jdi-fhd-r63452.o
 obj-$(CONFIG_DRM_PANEL_KHADAS_TS050) += panel-khadas-ts050.o
 obj-$(CONFIG_DRM_PANEL_KINGDISPLAY_KD097D04) += panel-kingdisplay-kd097d04.o
+obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK028QV25BYL) += panel-leadtek-ltk028qv25byl.o
 obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK050H3146W) += panel-leadtek-ltk050h3146w.o
 obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK500HD1829) += panel-leadtek-ltk500hd1829.o
 obj-$(CONFIG_DRM_PANEL_LINCOLNTECH_LCD197) += panel-lincolntech-lcd197.o
diff --git a/drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c b/drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c
new file mode 100644
index 000000000000..2e3482b2b95c
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Leadtek LTK08QV25BYL 2.8" MIPI-DSI panel driver
+ * Copyright (c) 2025, Bootlin
+ *
+ * base on panel-leadtek-ltk050h346w.c
+ * Copyright (C) 2020 Theobroma Systems Design und Consulting GmbH
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+
+#include <video/mipi_display.h>
+
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+
+struct ltk028qv25byl {
+	struct device *dev;
+	struct drm_panel panel;
+	struct gpio_desc *reset_gpio;
+	struct regulator *vci;
+	struct regulator *iovcc;
+};
+
+static inline struct ltk028qv25byl *panel_to_ltk028qv25byl(struct drm_panel *panel)
+{
+	return container_of(panel, struct ltk028qv25byl, panel);
+}
+
+static int ltk028qv25byl_init_sequence(struct ltk028qv25byl *ctx)
+{
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
+	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
+
+	/*
+	 * Init sequence was supplied by the panel vendor. All documentation
+	 * provided by the vendor (i.e comments in the provided init sequence)
+	 * is also given here as comments without modification.
+	 */
+
+	/* Password */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xdf, 0x98, 0x51, 0xe9);
+
+	/* Page 0 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde, 0x00);
+
+	/* VGMP, VGSP, VGMN, VGSN 4.3 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb7, 0x1e, 0x85, 0x1e, 0x33);
+
+	/* Set_R_GAMMA */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc8, 0x3f, 0x2e, 0x25, 0x21, 0x23,
+				     0x25, 0x1f, 0x1e, 0x1c, 0x1b, 0x19, 0x11,
+				     0x0e, 0x0a, 0x06, 0x0e, 0x3f, 0x2e, 0x26,
+				     0x21, 0x24, 0x25, 0x1f, 0x1f, 0x1d, 0x1c,
+				     0x19,  0x11,  0x0e,  0x0a,  0x06,  0x0e);
+
+	/* POW_CTRL */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb9, 0x33, 0x08, 0xcc);
+
+	/* DCDC_SEL */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xbb, 0x44, 0x7a, 0x30, 0x40, 0x7c,
+				     0x60, 0x70, 0x70);
+
+	/* VDD_CTRL */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xbc, 0x38, 0x3c);
+
+	/* SETSTBA */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc0, 0x31, 0x20);
+
+	/* SETPANEL(default) */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc1, 0x12);
+
+	/* SETRGBCYC */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc3, 0x08, 0x00, 0x0a, 0x10, 0x08,
+				     0x54, 0x45, 0x71, 0x2c);
+
+	/* SETRGBCYC(default) */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc4, 0x00, 0xa0, 0x79, 0x0e, 0x0a,
+				     0x16, 0x79, 0x0e, 0x0a, 0x16, 0x79, 0x0e,
+				     0x0a, 0x16, 0x82, 0x00, 0x03);
+
+	/* SET_GD(default) */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xd0, 0x04, 0x0c, 0x6a, 0x0f, 0x00, 0x03);
+
+	/* RAMCTRL(default) */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx,  0xd7,  0x13,  0x00);
+
+	/* Page 2 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx,  0xde,  0x02);
+
+	/* DCDC_SET */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb8, 0x1d, 0xa0, 0x2f, 0x2c, 0x2b);
+
+	/* SETRGBCYC2 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc1, 0x10, 0x66, 0x66, 0x01);
+
+	/* Page 0 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde, 0x00);
+
+	/* SLPOUT  + 120ms delay */
+	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx);
+	mipi_dsi_msleep(&dsi_ctx, 120);
+
+	/* Page 2 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde,  0x02);
+
+	/* OSCM */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc5, 0x4e, 0x00, 0x00);
+
+	/* SETMIPI_2 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xca, 0x30, 0x20, 0xf4);
+
+	/* Page 4 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde, 0x04);
+
+	/* SETPHY3 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xd3, 0x3c);
+
+	/* Page 0 */
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde, 0x00);
+
+	/* Display on + 20ms delay */
+	mipi_dsi_dcs_set_display_on_multi(&dsi_ctx);
+	mipi_dsi_msleep(&dsi_ctx, 20);
+
+	return dsi_ctx.accum_err;
+}
+
+static int ltk028qv25byl_unprepare(struct drm_panel *panel)
+{
+	struct ltk028qv25byl *ctx = panel_to_ltk028qv25byl(panel);
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
+	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
+
+	mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
+	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx);
+	if (dsi_ctx.accum_err)
+		return dsi_ctx.accum_err;
+
+	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+
+	regulator_disable(ctx->iovcc);
+	regulator_disable(ctx->vci);
+
+	return 0;
+}
+
+static int ltk028qv25byl_prepare(struct drm_panel *panel)
+{
+	struct ltk028qv25byl *ctx = panel_to_ltk028qv25byl(panel);
+	int ret;
+
+	ret = regulator_enable(ctx->vci);
+	if (ret < 0) {
+		dev_err(ctx->dev, "Failed to enable vcc supply (%d)\n", ret);
+		return ret;
+	}
+	ret = regulator_enable(ctx->iovcc);
+	if (ret < 0) {
+		dev_err(ctx->dev, "Failed to enable iovcc supply (%d)\n", ret);
+		goto disable_vci;
+	}
+
+	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+	usleep_range(5000, 6000);
+	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
+	msleep(20);
+
+	ret = ltk028qv25byl_init_sequence(ctx);
+	if (ret)
+		goto force_reset;
+
+	return 0;
+
+force_reset:
+	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+	regulator_disable(ctx->iovcc);
+disable_vci:
+	regulator_disable(ctx->vci);
+	return ret;
+}
+
+static const struct drm_display_mode ltk028qv25byl_mode = {
+	.hdisplay       = 240,
+	.hsync_start    = 240 + 120,
+	.hsync_end      = 240 + 120 + 4,
+	.htotal         = 240 + 120 + 4 + 120,
+	.vdisplay       = 320,
+	.vsync_start    = 320 + 8,
+	.vsync_end      = 320 + 8 + 2,
+	.vtotal         = 320 + 8 + 2 + 6,
+	.clock          = 10000000 / 1000,
+	.flags          = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
+	.width_mm       = 45,
+	.height_mm      = 62,
+};
+
+static int ltk028qv25byl_get_modes(struct drm_panel *panel,
+				   struct drm_connector *connector)
+{
+	struct drm_display_mode *mode;
+
+	mode = drm_mode_duplicate(connector->dev, &ltk028qv25byl_mode);
+	if (!mode)
+		return -ENOMEM;
+
+	drm_mode_set_name(mode);
+
+	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
+	connector->display_info.width_mm = mode->width_mm;
+	connector->display_info.height_mm = mode->height_mm;
+	drm_mode_probed_add(connector, mode);
+
+	return 1;
+}
+
+static const struct drm_panel_funcs ltk028qv25byl_funcs = {
+	.unprepare = ltk028qv25byl_unprepare,
+	.prepare = ltk028qv25byl_prepare,
+	.get_modes = ltk028qv25byl_get_modes,
+};
+
+static int ltk028qv25byl_probe(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct ltk028qv25byl *ctx;
+	int ret;
+
+	ctx = devm_drm_panel_alloc(dev, __typeof(*ctx), panel,
+				   &ltk028qv25byl_funcs,
+				   DRM_MODE_CONNECTOR_DSI);
+	if (IS_ERR(ctx))
+		return PTR_ERR(ctx);
+
+	ctx->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(ctx->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(ctx->reset_gpio),
+				     "Failed to get reset gpio\n");
+
+	ctx->vci = devm_regulator_get(dev, "vci");
+	if (IS_ERR(ctx->vci))
+		return dev_err_probe(dev, PTR_ERR(ctx->vci),
+				     "Failed to get vcc regulator\n");
+
+	ctx->iovcc = devm_regulator_get(dev, "iovcc");
+	if (IS_ERR(ctx->iovcc))
+		return dev_err_probe(dev, PTR_ERR(ctx->iovcc),
+				     "Failed to get iovcc regulator\n");
+
+	mipi_dsi_set_drvdata(dsi, ctx);
+
+	ctx->dev = dev;
+
+	dsi->lanes = 1;
+	dsi->format = MIPI_DSI_FMT_RGB888;
+	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
+			  MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_NO_EOT_PACKET;
+
+	ret = drm_panel_of_backlight(&ctx->panel);
+	if (ret)
+		return ret;
+
+	drm_panel_add(&ctx->panel);
+
+	ret = devm_mipi_dsi_attach(dev, dsi);
+	if (ret < 0) {
+		drm_panel_remove(&ctx->panel);
+		return dev_err_probe(dev, ret, "Failed to attach to DSI host\n");
+	}
+
+	return 0;
+}
+
+static void ltk028qv25byl_remove(struct mipi_dsi_device *dsi)
+{
+	struct ltk028qv25byl *ctx = mipi_dsi_get_drvdata(dsi);
+
+	drm_panel_remove(&ctx->panel);
+}
+
+static const struct of_device_id ltk028qv25byl_of_match[] = {
+	{ .compatible = "leadtek,ltk028qv25byl" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ltk028qv25byl_of_match);
+
+static struct mipi_dsi_driver ltk028qv25byl_driver = {
+	.driver = {
+		.name = "panel-leadtek-ltk028qv25byl",
+		.of_match_table = ltk028qv25byl_of_match,
+	},
+	.probe	= ltk028qv25byl_probe,
+	.remove = ltk028qv25byl_remove,
+};
+module_mipi_dsi_driver(ltk028qv25byl_driver);
+
+MODULE_AUTHOR("Herve Codina <herve.codina@bootlin.com>");
+MODULE_DESCRIPTION("DRM driver for Leadtek LTK028QV25BYL MIPI DSI panel");
+MODULE_LICENSE("GPL");
-- 
2.51.0

[PATCH 3/3] MAINTAINERS: Add the Leadtek LTK028QV25BYL panel driver entry

[Herve Codina]

After contributing the driver, add myself as the maintainer for the
Leadtek LTK028QV25BYL panel driver.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 46126ce2f968..67c085cd1dae 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7811,6 +7811,13 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/display/panel/jadard,jd9365da-h3.yaml
 F:	drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
 
+DRM DRIVER FOR LEADTEK LTK028QV25BYL PANELS
+M:	Herve Codina <herve.codina@bootlin.com>
+S:	Maintained
+T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
+F:	Documentation/devicetree/bindings/display/panel/leadtek,ltk028qv25byl.yaml
+F:	drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c
+
 DRM DRIVER FOR LG SW43408 PANELS
 M:	Sumit Semwal <sumit.semwal@linaro.org>
 M:	Casey Connolly <casey.connolly@linaro.org>
-- 
2.51.0

Re: [PATCH 1/3] dt-bindings: display: panel: Add the Leadtek LTK08QV25BYL panel

[Conor Dooley]

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On Tue, Oct 21, 2025 at 09:34:03AM +0200, Herve Codina wrote:
> The Leadtek LTK08QV25BYL is a 2.8" 240x320 DSI display.
> 
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>

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

[-- Attachment #2: signature.asc --]
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Re: [PATCH 2/3] drm/panel: Add support for the Leadtek LTK08QV25BYL panel

[Neil Armstrong]

On 10/21/25 09:34, Herve Codina wrote:
> The Leadtek LTK08QV25BYL is a 2.8" 240x320 DSI display.
> 
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> ---
>   drivers/gpu/drm/panel/Kconfig                 |  12 +
>   drivers/gpu/drm/panel/Makefile                |   1 +
>   .../drm/panel/panel-leadtek-ltk028qv25byl.c   | 304 ++++++++++++++++++
>   3 files changed, 317 insertions(+)
>   create mode 100644 drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 407c5f6a268b..faa417195b6e 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -367,6 +367,18 @@ config DRM_PANEL_KINGDISPLAY_KD097D04
>   	  24 bit RGB per pixel. It provides a MIPI DSI interface to
>   	  the host and has a built-in LED backlight.
>   
> +config DRM_PANEL_LEADTEK_LTK028QV25BYL
> +	tristate "Leadtek LTK028QV25BYL panel"
> +	depends on OF
> +	depends on DRM_MIPI_DSI
> +	depends on BACKLIGHT_CLASS_DEVICE
> +	help
> +	  Say Y here if you want to enable support for Leadtek LTK028QV25BYL
> +	  TFT-LCD modules. The panel has a 240x320 resolution and uses
> +	  18 bit RGB per pixel. It provides a MIPI DSI interface to
> +	  the host and has a built-in LED backlight.
> +
> +
>   config DRM_PANEL_LEADTEK_LTK050H3146W
>   	tristate "Leadtek LTK050H3146W panel"
>   	depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index 3615a761b44f..12073c34e0f5 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_DRM_PANEL_JDI_LPM102A188A) += panel-jdi-lpm102a188a.o
>   obj-$(CONFIG_DRM_PANEL_JDI_R63452) += panel-jdi-fhd-r63452.o
>   obj-$(CONFIG_DRM_PANEL_KHADAS_TS050) += panel-khadas-ts050.o
>   obj-$(CONFIG_DRM_PANEL_KINGDISPLAY_KD097D04) += panel-kingdisplay-kd097d04.o
> +obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK028QV25BYL) += panel-leadtek-ltk028qv25byl.o
>   obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK050H3146W) += panel-leadtek-ltk050h3146w.o
>   obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK500HD1829) += panel-leadtek-ltk500hd1829.o
>   obj-$(CONFIG_DRM_PANEL_LINCOLNTECH_LCD197) += panel-lincolntech-lcd197.o
> diff --git a/drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c b/drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c
> new file mode 100644
> index 000000000000..2e3482b2b95c
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c
> @@ -0,0 +1,304 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Leadtek LTK08QV25BYL 2.8" MIPI-DSI panel driver
> + * Copyright (c) 2025, Bootlin
> + *
> + * base on panel-leadtek-ltk050h346w.c
> + * Copyright (C) 2020 Theobroma Systems Design und Consulting GmbH
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <video/mipi_display.h>
> +
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_panel.h>
> +
> +struct ltk028qv25byl {
> +	struct device *dev;
> +	struct drm_panel panel;
> +	struct gpio_desc *reset_gpio;
> +	struct regulator *vci;
> +	struct regulator *iovcc;
> +};
> +
> +static inline struct ltk028qv25byl *panel_to_ltk028qv25byl(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct ltk028qv25byl, panel);
> +}
> +
> +static int ltk028qv25byl_init_sequence(struct ltk028qv25byl *ctx)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
> +	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
> +
> +	/*
> +	 * Init sequence was supplied by the panel vendor. All documentation
> +	 * provided by the vendor (i.e comments in the provided init sequence)
> +	 * is also given here as comments without modification.
> +	 */
> +
> +	/* Password */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xdf, 0x98, 0x51, 0xe9);
> +
> +	/* Page 0 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde, 0x00);
> +
> +	/* VGMP, VGSP, VGMN, VGSN 4.3 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb7, 0x1e, 0x85, 0x1e, 0x33);
> +
> +	/* Set_R_GAMMA */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc8, 0x3f, 0x2e, 0x25, 0x21, 0x23,
> +				     0x25, 0x1f, 0x1e, 0x1c, 0x1b, 0x19, 0x11,
> +				     0x0e, 0x0a, 0x06, 0x0e, 0x3f, 0x2e, 0x26,
> +				     0x21, 0x24, 0x25, 0x1f, 0x1f, 0x1d, 0x1c,
> +				     0x19,  0x11,  0x0e,  0x0a,  0x06,  0x0e);
> +
> +	/* POW_CTRL */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb9, 0x33, 0x08, 0xcc);
> +
> +	/* DCDC_SEL */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xbb, 0x44, 0x7a, 0x30, 0x40, 0x7c,
> +				     0x60, 0x70, 0x70);
> +
> +	/* VDD_CTRL */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xbc, 0x38, 0x3c);
> +
> +	/* SETSTBA */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc0, 0x31, 0x20);
> +
> +	/* SETPANEL(default) */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc1, 0x12);
> +
> +	/* SETRGBCYC */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc3, 0x08, 0x00, 0x0a, 0x10, 0x08,
> +				     0x54, 0x45, 0x71, 0x2c);
> +
> +	/* SETRGBCYC(default) */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc4, 0x00, 0xa0, 0x79, 0x0e, 0x0a,
> +				     0x16, 0x79, 0x0e, 0x0a, 0x16, 0x79, 0x0e,
> +				     0x0a, 0x16, 0x82, 0x00, 0x03);
> +
> +	/* SET_GD(default) */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xd0, 0x04, 0x0c, 0x6a, 0x0f, 0x00, 0x03);
> +
> +	/* RAMCTRL(default) */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx,  0xd7,  0x13,  0x00);
> +
> +	/* Page 2 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx,  0xde,  0x02);
> +
> +	/* DCDC_SET */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb8, 0x1d, 0xa0, 0x2f, 0x2c, 0x2b);
> +
> +	/* SETRGBCYC2 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc1, 0x10, 0x66, 0x66, 0x01);
> +
> +	/* Page 0 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde, 0x00);
> +
> +	/* SLPOUT  + 120ms delay */
> +	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx);
> +	mipi_dsi_msleep(&dsi_ctx, 120);
> +
> +	/* Page 2 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde,  0x02);
> +
> +	/* OSCM */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xc5, 0x4e, 0x00, 0x00);
> +
> +	/* SETMIPI_2 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xca, 0x30, 0x20, 0xf4);
> +
> +	/* Page 4 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde, 0x04);
> +
> +	/* SETPHY3 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xd3, 0x3c);
> +
> +	/* Page 0 */
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xde, 0x00);
> +
> +	/* Display on + 20ms delay */
> +	mipi_dsi_dcs_set_display_on_multi(&dsi_ctx);
> +	mipi_dsi_msleep(&dsi_ctx, 20);
> +
> +	return dsi_ctx.accum_err;
> +}
> +
> +static int ltk028qv25byl_unprepare(struct drm_panel *panel)
> +{
> +	struct ltk028qv25byl *ctx = panel_to_ltk028qv25byl(panel);
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
> +	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
> +
> +	mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
> +	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx);
> +	if (dsi_ctx.accum_err)
> +		return dsi_ctx.accum_err;
> +
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
> +
> +	regulator_disable(ctx->iovcc);
> +	regulator_disable(ctx->vci);
> +
> +	return 0;
> +}
> +
> +static int ltk028qv25byl_prepare(struct drm_panel *panel)
> +{
> +	struct ltk028qv25byl *ctx = panel_to_ltk028qv25byl(panel);
> +	int ret;
> +
> +	ret = regulator_enable(ctx->vci);
> +	if (ret < 0) {
> +		dev_err(ctx->dev, "Failed to enable vcc supply (%d)\n", ret);
> +		return ret;
> +	}
> +	ret = regulator_enable(ctx->iovcc);
> +	if (ret < 0) {
> +		dev_err(ctx->dev, "Failed to enable iovcc supply (%d)\n", ret);
> +		goto disable_vci;
> +	}
> +
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
> +	usleep_range(5000, 6000);
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
> +	msleep(20);
> +
> +	ret = ltk028qv25byl_init_sequence(ctx);
> +	if (ret)
> +		goto force_reset;
> +
> +	return 0;
> +
> +force_reset:
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
> +	regulator_disable(ctx->iovcc);
> +disable_vci:
> +	regulator_disable(ctx->vci);
> +	return ret;
> +}
> +
> +static const struct drm_display_mode ltk028qv25byl_mode = {
> +	.hdisplay       = 240,
> +	.hsync_start    = 240 + 120,
> +	.hsync_end      = 240 + 120 + 4,
> +	.htotal         = 240 + 120 + 4 + 120,
> +	.vdisplay       = 320,
> +	.vsync_start    = 320 + 8,
> +	.vsync_end      = 320 + 8 + 2,
> +	.vtotal         = 320 + 8 + 2 + 6,
> +	.clock          = 10000000 / 1000,

Usually we calculate the clock from the mode parameters, won't it work here ?

> +	.flags          = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
> +	.width_mm       = 45,
> +	.height_mm      = 62,
> +};
> +
> +static int ltk028qv25byl_get_modes(struct drm_panel *panel,
> +				   struct drm_connector *connector)
> +{
> +	struct drm_display_mode *mode;
> +
> +	mode = drm_mode_duplicate(connector->dev, &ltk028qv25byl_mode);
> +	if (!mode)
> +		return -ENOMEM;
> +
> +	drm_mode_set_name(mode);
> +
> +	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
> +	connector->display_info.width_mm = mode->width_mm;
> +	connector->display_info.height_mm = mode->height_mm;
> +	drm_mode_probed_add(connector, mode);
> +
> +	return 1;
> +}
> +
> +static const struct drm_panel_funcs ltk028qv25byl_funcs = {
> +	.unprepare = ltk028qv25byl_unprepare,
> +	.prepare = ltk028qv25byl_prepare,
> +	.get_modes = ltk028qv25byl_get_modes,
> +};
> +
> +static int ltk028qv25byl_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct ltk028qv25byl *ctx;
> +	int ret;
> +
> +	ctx = devm_drm_panel_alloc(dev, __typeof(*ctx), panel,
> +				   &ltk028qv25byl_funcs,
> +				   DRM_MODE_CONNECTOR_DSI);
> +	if (IS_ERR(ctx))
> +		return PTR_ERR(ctx);
> +
> +	ctx->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR(ctx->reset_gpio))
> +		return dev_err_probe(dev, PTR_ERR(ctx->reset_gpio),
> +				     "Failed to get reset gpio\n");
> +
> +	ctx->vci = devm_regulator_get(dev, "vci");
> +	if (IS_ERR(ctx->vci))
> +		return dev_err_probe(dev, PTR_ERR(ctx->vci),
> +				     "Failed to get vcc regulator\n");
> +
> +	ctx->iovcc = devm_regulator_get(dev, "iovcc");
> +	if (IS_ERR(ctx->iovcc))
> +		return dev_err_probe(dev, PTR_ERR(ctx->iovcc),
> +				     "Failed to get iovcc regulator\n");

Can you switch to devm_regulator_bulk_get_const() ?

> +
> +	mipi_dsi_set_drvdata(dsi, ctx);
> +
> +	ctx->dev = dev;
> +
> +	dsi->lanes = 1;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
> +			  MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_NO_EOT_PACKET;
> +
> +	ret = drm_panel_of_backlight(&ctx->panel);
> +	if (ret)
> +		return ret;
> +
> +	drm_panel_add(&ctx->panel);
> +
> +	ret = devm_mipi_dsi_attach(dev, dsi);
> +	if (ret < 0) {
> +		drm_panel_remove(&ctx->panel);
> +		return dev_err_probe(dev, ret, "Failed to attach to DSI host\n");
> +	}
> +
> +	return 0;
> +}
> +
> +static void ltk028qv25byl_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct ltk028qv25byl *ctx = mipi_dsi_get_drvdata(dsi);
> +
> +	drm_panel_remove(&ctx->panel);
> +}
> +
> +static const struct of_device_id ltk028qv25byl_of_match[] = {
> +	{ .compatible = "leadtek,ltk028qv25byl" },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, ltk028qv25byl_of_match);
> +
> +static struct mipi_dsi_driver ltk028qv25byl_driver = {
> +	.driver = {
> +		.name = "panel-leadtek-ltk028qv25byl",
> +		.of_match_table = ltk028qv25byl_of_match,
> +	},
> +	.probe	= ltk028qv25byl_probe,
> +	.remove = ltk028qv25byl_remove,
> +};
> +module_mipi_dsi_driver(ltk028qv25byl_driver);
> +
> +MODULE_AUTHOR("Herve Codina <herve.codina@bootlin.com>");
> +MODULE_DESCRIPTION("DRM driver for Leadtek LTK028QV25BYL MIPI DSI panel");
> +MODULE_LICENSE("GPL");

Thanks,
Neil

Re: [PATCH 3/3] MAINTAINERS: Add the Leadtek LTK028QV25BYL panel driver entry

[Neil Armstrong]

On 10/21/25 09:34, Herve Codina wrote:
> After contributing the driver, add myself as the maintainer for the
> Leadtek LTK028QV25BYL panel driver.
> 
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> ---
>   MAINTAINERS | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 46126ce2f968..67c085cd1dae 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7811,6 +7811,13 @@ S:	Maintained
>   F:	Documentation/devicetree/bindings/display/panel/jadard,jd9365da-h3.yaml
>   F:	drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
>   
> +DRM DRIVER FOR LEADTEK LTK028QV25BYL PANELS
> +M:	Herve Codina <herve.codina@bootlin.com>
> +S:	Maintained
> +T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
> +F:	Documentation/devicetree/bindings/display/panel/leadtek,ltk028qv25byl.yaml
> +F:	drivers/gpu/drm/panel/panel-leadtek-ltk028qv25byl.c
> +
>   DRM DRIVER FOR LG SW43408 PANELS
>   M:	Sumit Semwal <sumit.semwal@linaro.org>
>   M:	Casey Connolly <casey.connolly@linaro.org>

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

Re: [PATCH 2/3] drm/panel: Add support for the Leadtek LTK08QV25BYL panel

[Herve Codina]

Hi Neil,

On Wed, 29 Oct 2025 21:45:24 +0100
Neil Armstrong <neil.armstrong@linaro.org> wrote:

...

> > +
> > +static const struct drm_display_mode ltk028qv25byl_mode = {
> > +	.hdisplay       = 240,
> > +	.hsync_start    = 240 + 120,
> > +	.hsync_end      = 240 + 120 + 4,
> > +	.htotal         = 240 + 120 + 4 + 120,
> > +	.vdisplay       = 320,
> > +	.vsync_start    = 320 + 8,
> > +	.vsync_end      = 320 + 8 + 2,
> > +	.vtotal         = 320 + 8 + 2 + 6,
> > +	.clock          = 10000000 / 1000,  
> 
> Usually we calculate the clock from the mode parameters, won't it work here ?
> 

The panel has an internal oscillator an the data transfer need to be sync with
this oscillator.

10M pixel per sec is the value set by the vendor.
I tried to use a value based on other mode parameters such as
  (240 + 120 + 4 + 120) * (320 + 8 + 2 + 6) * 60 / 1000

and it didn't work. I also tried ' ... * 90 / 1000) and ' ... * 100 / 1000)
without better results.

I can add a comment if you want in the next iteration to spot the value:
--- 8< ---
	.clock          = 10000000 / 1000,  /* 10 Mbps, internal panel oscillator */
--- 8< ---

Let me know.


...

> > +	ctx->iovcc = devm_regulator_get(dev, "iovcc");
> > +	if (IS_ERR(ctx->iovcc))
> > +		return dev_err_probe(dev, PTR_ERR(ctx->iovcc),
> > +				     "Failed to get iovcc regulator\n");  
> 
> Can you switch to devm_regulator_bulk_get_const() ?

Yes, I will do that in the next iteration.

Best regards,
Hervé