[PATCH 1/3 v2] dt-bindings: Add vendor prefix for Hydis technologies

[PATCH 1/3 v2] dt-bindings: Add vendor prefix for Hydis technologies

[Linus Walleij]

This vendor has produced a number of display panels,
including HVA40WV1.

Cc: devicetree@vger.kernel.org
Cc: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v1->v2:
- New patch adding this vendor.
---
 Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
index 9e67944bec9c..95ef233dbb52 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
+++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
@@ -421,6 +421,8 @@ patternProperties:
     description: Shenzhen Hugsun Technology Co. Ltd.
   "^hwacom,.*":
     description: HwaCom Systems Inc.
+  "^hydis,.*":
+    description: Hydis Technologies
   "^hyundai,.*":
     description: Hyundai Technology
   "^i2se,.*":
-- 
2.21.1

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[PATCH 2/3 v2] drm/panel: Add DT bindings for Novatek NT35510-based panels

[Linus Walleij]

This adds device tree bindings for the Novatek NT35510-based
family of panels. Since several such panels are in existence
we define bindings common for all, and define the compatible
string for one certain panel (Hydis HVA40WV1).

As other panels are discovered and investigated, we can add
more compatibles to the binding using oneOf constructions.

Cc: Stephan Gerhold <stephan@gerhold.net>
Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v1->v2:
- Rename file to novatek,nt35510,yaml to match the first
  compatible.
- Require both the specific display manufacturer compatible
  and the novatek,nt35510 compatible in strict sequence.
---
 .../display/panel/novatek,nt35510.yaml        | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml

diff --git a/Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml b/Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
new file mode 100644
index 000000000000..791fc9daa68b
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/panel/novatek,nt35510.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Novatek NT35510-based display panels
+
+maintainers:
+  - Linus Walleij <linus.walleij@linaro.org>
+
+allOf:
+  - $ref: panel-common.yaml#
+
+properties:
+  compatible:
+    items:
+      - const: hydis,hva40wv1
+      - const: novatek,nt35510
+    description: This indicates the panel manufacturer of the panel
+      that is in turn using the NT35510 panel driver. The compatible
+      string determines how the NT35510 panel driver shall be configured
+      to work with the indicated panel. The novatek,nt35510 compatible shall
+      always be provided as a fallback.
+  reg: true
+  reset-gpios: true
+  vdd-supply:
+     description: regulator that supplies the vdd voltage
+  vddi-supply:
+     description: regulator that supplies the vddi voltage
+  backlight: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    dsi@a0351000 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        panel {
+            compatible = "hydis,hva40wv1", "novatek,nt35510";
+            reg = <0>;
+            vdd-supply = <&ab8500_ldo_aux4_reg>;
+            vddi-supply = <&ab8500_ldo_aux6_reg>;
+            reset-gpios = <&gpio4 11 GPIO_ACTIVE_LOW>;
+            backlight = <&gpio_bl>;
+        };
+    };
+
+...
-- 
2.21.1

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Re: [PATCH 2/3 v2] drm/panel: Add DT bindings for Novatek NT35510-based panels

[Rob Herring]

On Sun, 23 Feb 2020 13:18:40 +0100, Linus Walleij wrote:
> This adds device tree bindings for the Novatek NT35510-based
> family of panels. Since several such panels are in existence
> we define bindings common for all, and define the compatible
> string for one certain panel (Hydis HVA40WV1).
> 
> As other panels are discovered and investigated, we can add
> more compatibles to the binding using oneOf constructions.
> 
> Cc: Stephan Gerhold <stephan@gerhold.net>
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ChangeLog v1->v2:
> - Rename file to novatek,nt35510,yaml to match the first
>   compatible.
> - Require both the specific display manufacturer compatible
>   and the novatek,nt35510 compatible in strict sequence.
> ---
>  .../display/panel/novatek,nt35510.yaml        | 56 +++++++++++++++++++
>  1 file changed, 56 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>
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Re: [PATCH 2/3 v2] drm/panel: Add DT bindings for Novatek NT35510-based panels

[Sam Ravnborg]

On Sun, Feb 23, 2020 at 01:18:40PM +0100, Linus Walleij wrote:
> This adds device tree bindings for the Novatek NT35510-based
> family of panels. Since several such panels are in existence
> we define bindings common for all, and define the compatible
> string for one certain panel (Hydis HVA40WV1).
> 
> As other panels are discovered and investigated, we can add
> more compatibles to the binding using oneOf constructions.
> 
> Cc: Stephan Gerhold <stephan@gerhold.net>
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Applied to drm-misc-next.

	Sam

> ---
> ChangeLog v1->v2:
> - Rename file to novatek,nt35510,yaml to match the first
>   compatible.
> - Require both the specific display manufacturer compatible
>   and the novatek,nt35510 compatible in strict sequence.
> ---
>  .../display/panel/novatek,nt35510.yaml        | 56 +++++++++++++++++++
>  1 file changed, 56 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
> 
> diff --git a/Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml b/Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
> new file mode 100644
> index 000000000000..791fc9daa68b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
> @@ -0,0 +1,56 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/panel/novatek,nt35510.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Novatek NT35510-based display panels
> +
> +maintainers:
> +  - Linus Walleij <linus.walleij@linaro.org>
> +
> +allOf:
> +  - $ref: panel-common.yaml#
> +
> +properties:
> +  compatible:
> +    items:
> +      - const: hydis,hva40wv1
> +      - const: novatek,nt35510
> +    description: This indicates the panel manufacturer of the panel
> +      that is in turn using the NT35510 panel driver. The compatible
> +      string determines how the NT35510 panel driver shall be configured
> +      to work with the indicated panel. The novatek,nt35510 compatible shall
> +      always be provided as a fallback.
> +  reg: true
> +  reset-gpios: true
> +  vdd-supply:
> +     description: regulator that supplies the vdd voltage
> +  vddi-supply:
> +     description: regulator that supplies the vddi voltage
> +  backlight: true
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    dsi@a0351000 {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +        panel {
> +            compatible = "hydis,hva40wv1", "novatek,nt35510";
> +            reg = <0>;
> +            vdd-supply = <&ab8500_ldo_aux4_reg>;
> +            vddi-supply = <&ab8500_ldo_aux6_reg>;
> +            reset-gpios = <&gpio4 11 GPIO_ACTIVE_LOW>;
> +            backlight = <&gpio_bl>;
> +        };
> +    };
> +
> +...
> -- 
> 2.21.1
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[PATCH 3/3 v2] drm/panel: Add driver for Novatek NT35510-based panels

[Linus Walleij]

This adds a driver for panels based on the Novatek NT35510
display driver IC, such as the Hydis HVA40WV1 panel found
in the Samsung GT-S7710.

The NT35510 can be used with both internal and external
backlight (such as GPIO backlight) so we support both:
if no external backlight is found, we register a subdriver
for the internal backlight.

Cc: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v1->v2:
- Rebase onto v5.6-rc1
- Account for changes in the panel struct and get_modes()
  passing the connector as argument.
- Use specific full filename for the panel driver.
- Update to match rename of DT binding file.
- Drop select VIDEO_MODE_HELPERS
- Fix spelling errors and stray characters, call 4bit groups
  nibbles rather than nybbles
- Alphabetize includes and order them as requested by Sam
- Drop the surplus videomode includes
- Drop any backlight handling from .enable() and .disable()
  callbacks and rely on the backlight handling in the DRM
  panel core, but still assign a backlight from within the
  driver if we don't find one in the device tree.
---
 MAINTAINERS                                   |    7 +
 drivers/gpu/drm/panel/Kconfig                 |   10 +
 drivers/gpu/drm/panel/Makefile                |    1 +
 drivers/gpu/drm/panel/panel-novatek-nt35510.c | 1098 +++++++++++++++++
 4 files changed, 1116 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-novatek-nt35510.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 17f502467c8a..8e7433d74530 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5322,6 +5322,13 @@ F:	drivers/gpu/drm/msm/
 F:	include/uapi/drm/msm_drm.h
 F:	Documentation/devicetree/bindings/display/msm/
 
+DRM DRIVER FOR NOVATEK NT35510 PANELS
+M:	Linus Walleij <linus.walleij@linaro.org>
+T:	git git://anongit.freedesktop.org/drm/drm-misc
+S:	Maintained
+F:	drivers/gpu/drm/panel/panel-novatek-nt35510.c
+F:	Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
+
 DRM DRIVER FOR NVIDIA GEFORCE/QUADRO GPUS
 M:	Ben Skeggs <bskeggs@redhat.com>
 L:	dri-devel@lists.freedesktop.org
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 19eac3d799a7..b37495a5acce 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -149,6 +149,16 @@ config DRM_PANEL_NEC_NL8048HL11
 	  panel (found on the Zoom2/3/3630 SDP boards). To compile this driver
 	  as a module, choose M here.
 
+config DRM_PANEL_NOVATEK_NT35510
+	tristate "Novatek NT35510 RGB panel driver"
+	depends on OF
+	depends on DRM_MIPI_DSI
+	depends on BACKLIGHT_CLASS_DEVICE
+	help
+	  Say Y here if you want to enable support for the panels built
+	  around the Novatek NT35510 display controller, such as some
+	  Hydis panels.
+
 config DRM_PANEL_NOVATEK_NT39016
 	tristate "Novatek NT39016 RGB/SPI panel"
 	depends on OF && SPI
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index c4ca0e3b9b3c..7bc8a57ede2b 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK500HD1829) += panel-leadtek-ltk500hd1829.o
 obj-$(CONFIG_DRM_PANEL_LG_LB035Q02) += panel-lg-lb035q02.o
 obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
 obj-$(CONFIG_DRM_PANEL_NEC_NL8048HL11) += panel-nec-nl8048hl11.o
+obj-$(CONFIG_DRM_PANEL_NOVATEK_NT35510) += panel-novatek-nt35510.o
 obj-$(CONFIG_DRM_PANEL_NOVATEK_NT39016) += panel-novatek-nt39016.o
 obj-$(CONFIG_DRM_PANEL_OLIMEX_LCD_OLINUXINO) += panel-olimex-lcd-olinuxino.o
 obj-$(CONFIG_DRM_PANEL_ORISETECH_OTM8009A) += panel-orisetech-otm8009a.o
diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35510.c b/drivers/gpu/drm/panel/panel-novatek-nt35510.c
new file mode 100644
index 000000000000..b4c014126781
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-novatek-nt35510.c
@@ -0,0 +1,1098 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Novatek NT35510 panel driver
+ * Copyright (C) 2020 Linus Walleij <linus.walleij@linaro.org>
+ * Based on code by Robert Teather (C) 2012 Samsung
+ *
+ * This display driver (and I refer to the physical component NT35510,
+ * not this Linux kernel software driver) can handle:
+ * 480x864, 480x854, 480x800, 480x720 and 480x640 pixel displays.
+ * It has 480x840x24bit SRAM embedded for storing a frame.
+ * When powered on the display is by default in 480x800 mode.
+ *
+ * The actual panels using this component have different names, but
+ * the code needed to set up and configure the panel will be similar,
+ * so they should all use the NT35510 driver with appropriate configuration
+ * per-panel, e.g. for physical size.
+ *
+ * This driver is for the DSI interface to panels using the NT35510.
+ *
+ * The NT35510 can also use an RGB (DPI) interface combined with an
+ * I2C or SPI interface for setting up the NT35510. If this is needed
+ * this panel driver should be refactored to also support that use
+ * case.
+ */
+#include <linux/backlight.h>
+#include <linux/bitops.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/regmap.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>
+#include <drm/drm_print.h>
+
+#define MCS_CMD_MAUCCTR		0xF0 /* Manufacturer command enable */
+#define MCS_CMD_READ_ID1	0xDA
+#define MCS_CMD_READ_ID2	0xDB
+#define MCS_CMD_READ_ID3	0xDC
+#define MCS_CMD_MTP_READ_SETTING 0xF8 /* Uncertain about name */
+#define MCS_CMD_MTP_READ_PARAM 0xFF /* Uncertain about name */
+
+/*
+ * These manufacturer commands are available after we enable manufacturer
+ * command set (MCS) for page 0.
+ */
+#define NT35510_P0_DOPCTR 0xB1
+#define NT35510_P0_SDHDTCTR 0xB6
+#define NT35510_P0_GSEQCTR 0xB7
+#define NT35510_P0_SDEQCTR 0xB8
+#define NT35510_P0_SDVPCTR 0xBA
+#define NT35510_P0_DPFRCTR1 0xBD
+#define NT35510_P0_DPFRCTR2 0xBE
+#define NT35510_P0_DPFRCTR3 0xBF
+#define NT35510_P0_DPMCTR12 0xCC
+
+#define NT35510_P0_DOPCTR_LEN 2
+#define NT35510_P0_GSEQCTR_LEN 2
+#define NT35510_P0_SDEQCTR_LEN 4
+#define NT35510_P0_SDVPCTR_LEN 1
+#define NT35510_P0_DPFRCTR1_LEN 5
+#define NT35510_P0_DPFRCTR2_LEN 5
+#define NT35510_P0_DPFRCTR3_LEN 5
+#define NT35510_P0_DPMCTR12_LEN 3
+
+#define NT35510_DOPCTR_0_RAMKP BIT(7) /* Contents kept in sleep */
+#define NT35510_DOPCTR_0_DSITE BIT(6) /* Enable TE signal */
+#define NT35510_DOPCTR_0_DSIG BIT(5) /* Enable generic read/write */
+#define NT35510_DOPCTR_0_DSIM BIT(4) /* Enable video mode on DSI */
+#define NT35510_DOPCTR_0_EOTP BIT(3) /* Support EoTP */
+#define NT35510_DOPCTR_0_N565 BIT(2) /* RGB or BGR pixel format */
+#define NT35510_DOPCTR_1_TW_PWR_SEL BIT(4) /* TE power selector */
+#define NT35510_DOPCTR_1_CRGB BIT(3) /* RGB or BGR byte order */
+#define NT35510_DOPCTR_1_CTB BIT(2) /* Vertical scanning direction */
+#define NT35510_DOPCTR_1_CRL BIT(1) /* Source driver data shift */
+#define NT35510_P0_SDVPCTR_PRG BIT(2) /* 0 = normal operation, 1 = VGLO */
+#define NT35510_P0_SDVPCTR_AVDD 0 /* source driver output = AVDD */
+#define NT35510_P0_SDVPCTR_OFFCOL 1 /* source driver output = off color */
+#define NT35510_P0_SDVPCTR_AVSS 2 /* source driver output = AVSS */
+#define NT35510_P0_SDVPCTR_HI_Z 3 /* source driver output = High impedance */
+
+/*
+ * These manufacturer commands are available after we enable manufacturer
+ * command set (MCS) for page 1.
+ */
+#define NT35510_P1_SETAVDD 0xB0
+#define NT35510_P1_SETAVEE 0xB1
+#define NT35510_P1_SETVCL 0xB2
+#define NT35510_P1_SETVGH 0xB3
+#define NT35510_P1_SETVRGH 0xB4
+#define NT35510_P1_SETVGL 0xB5
+#define NT35510_P1_BT1CTR 0xB6
+#define NT35510_P1_BT2CTR 0xB7
+#define NT35510_P1_BT3CTR 0xB8
+#define NT35510_P1_BT4CTR 0xB9 /* VGH boosting times/freq */
+#define NT35510_P1_BT5CTR 0xBA
+#define NT35510_P1_PFMCTR 0xBB
+#define NT35510_P1_SETVGP 0xBC
+#define NT35510_P1_SETVGN 0xBD
+#define NT35510_P1_SETVCMOFF 0xBE
+#define NT35510_P1_VGHCTR 0xBF /* VGH output ctrl */
+#define NT35510_P1_SET_GAMMA_RED_POS 0xD1
+#define NT35510_P1_SET_GAMMA_GREEN_POS 0xD2
+#define NT35510_P1_SET_GAMMA_BLUE_POS 0xD3
+#define NT35510_P1_SET_GAMMA_RED_NEG 0xD4
+#define NT35510_P1_SET_GAMMA_GREEN_NEG 0xD5
+#define NT35510_P1_SET_GAMMA_BLUE_NEG 0xD6
+
+/* AVDD and AVEE setting 3 bytes */
+#define NT35510_P1_AVDD_LEN 3
+#define NT35510_P1_AVEE_LEN 3
+#define NT35510_P1_VGH_LEN 3
+#define NT35510_P1_VGL_LEN 3
+#define NT35510_P1_VGP_LEN 3
+#define NT35510_P1_VGN_LEN 3
+/* BT1CTR thru BT5CTR setting 3 bytes */
+#define NT35510_P1_BT1CTR_LEN 3
+#define NT35510_P1_BT2CTR_LEN 3
+#define NT35510_P1_BT4CTR_LEN 3
+#define NT35510_P1_BT5CTR_LEN 3
+/* 52 gamma parameters times two per color: positive and negative */
+#define NT35510_P1_GAMMA_LEN 52
+
+/**
+ * struct nt35510_config - the display-specific NT35510 configuration
+ *
+ * Some of the settings provide an array of bytes, A, B C which mean:
+ * A = normal / idle off mode
+ * B = idle on mode
+ * C = partial / idle off mode
+ *
+ * Gamma correction arrays are 10bit numbers, two consecutive bytes
+ * makes out one point on the gamma correction curve. The points are
+ * not linearly placed along the X axis, we get points 0, 1, 3, 5
+ * 7, 11, 15, 23, 31, 47, 63, 95, 127, 128, 160, 192, 208, 224, 232,
+ * 240, 244, 248, 250, 252, 254, 255. The voltages tuples form
+ * V0, V1, V3 ... V255, with 0x0000 being the lowest voltage and
+ * 0x03FF being the highest voltage.
+ *
+ * Each value must be strictly higher than the previous value forming
+ * a rising curve like this:
+ *
+ * ^
+ * |                                        V255
+ * |                                 V254
+ * |                         ....
+ * |                    V5
+ * |           V3
+ * |     V1
+ * | V0
+ * +------------------------------------------->
+ *
+ * The details about all settings can be found in the NT35510 Application
+ * Note.
+ */
+struct nt35510_config {
+	/**
+	 * @width_mm: physical panel width [mm]
+	 */
+	u32 width_mm;
+	/**
+	 * @height_mm: physical panel height [mm]
+	 */
+	u32 height_mm;
+	/**
+	 * @mode: the display mode. This is only relevant outside the panel
+	 * in video mode: in command mode this is configuring the internal
+	 * timing in the display controller.
+	 */
+	const struct drm_display_mode mode;
+	/**
+	 * @avdd: setting for AVDD ranging from 0x00 = 6.5V to 0x14 = 4.5V
+	 * in 0.1V steps the default is 0x05 which means 6.0V
+	 */
+	u8 avdd[NT35510_P1_AVDD_LEN];
+	/**
+	 * @bt1ctr: setting for boost power control for the AVDD step-up
+	 * circuit (1)
+	 * bits 0..2 in the lower nibble controls PCK, the booster clock
+	 * frequency for the step-up circuit:
+	 * 0 = Hsync/32
+	 * 1 = Hsync/16
+	 * 2 = Hsync/8
+	 * 3 = Hsync/4
+	 * 4 = Hsync/2
+	 * 5 = Hsync
+	 * 6 = Hsync x 2
+	 * 7 = Hsync x 4
+	 * bits 4..6 in the upper nibble controls BTP, the boosting
+	 * amplification for the the step-up circuit:
+	 * 0 = Disable
+	 * 1 = 1.5 x VDDB
+	 * 2 = 1.66 x VDDB
+	 * 3 = 2 x VDDB
+	 * 4 = 2.5 x VDDB
+	 * 5 = 3 x VDDB
+	 * The defaults are 4 and 4 yielding 0x44
+	 */
+	u8 bt1ctr[NT35510_P1_BT1CTR_LEN];
+	/**
+	 * @avee: setting for AVEE ranging from 0x00 = -6.5V to 0x14 = -4.5V
+	 * in 0.1V steps the default is 0x05 which means -6.0V
+	 */
+	u8 avee[NT35510_P1_AVEE_LEN];
+	/**
+	 * @bt2ctr: setting for boost power control for the AVEE step-up
+	 * circuit (2)
+	 * bits 0..2 in the lower nibble controls NCK, the booster clock
+	 * frequency, the values are the same as for PCK in @bt1ctr.
+	 * bits 4..5 in the upper nibble controls BTN, the boosting
+	 * amplification for the the step-up circuit.
+	 * 0 = Disable
+	 * 1 = -1.5 x VDDB
+	 * 2 = -2 x VDDB
+	 * 3 = -2.5 x VDDB
+	 * 4 = -3 x VDDB
+	 * The defaults are 4 and 3 yielding 0x34
+	 */
+	u8 bt2ctr[NT35510_P1_BT2CTR_LEN];
+	/**
+	 * @vgh: setting for VGH ranging from 0x00 = 7.0V to 0x0B = 18.0V
+	 * in 1V steps, the default is 0x08 which means 15V
+	 */
+	u8 vgh[NT35510_P1_VGH_LEN];
+	/**
+	 * @bt4ctr: setting for boost power control for the VGH step-up
+	 * circuit (4)
+	 * bits 0..2 in the lower nibble controls HCK, the booster clock
+	 * frequency, the values are the same as for PCK in @bt1ctr.
+	 * bits 4..5 in the upper nibble controls BTH, the boosting
+	 * amplification for the the step-up circuit.
+	 * 0 = AVDD + VDDB
+	 * 1 = AVDD - AVEE
+	 * 2 = AVDD - AVEE + VDDB
+	 * 3 = AVDD x 2 - AVEE
+	 * The defaults are 4 and 3 yielding 0x34
+	 */
+	u8 bt4ctr[NT35510_P1_BT4CTR_LEN];
+	/**
+	 * @vgl: setting for VGL ranging from 0x00 = -2V to 0x0f = -15V in
+	 * 1V steps, the default is 0x08 which means -10V
+	 */
+	u8 vgl[NT35510_P1_VGL_LEN];
+	/**
+	 * @bt5ctr: setting for boost power control for the VGL step-up
+	 * circuit (5)
+	 * bits 0..2 in the lower nibble controls LCK, the booster clock
+	 * frequency, the values are the same as for PCK in @bt1ctr.
+	 * bits 4..5 in the upper nibble controls BTL, the boosting
+	 * amplification for the the step-up circuit.
+	 * 0 = AVEE + VCL
+	 * 1 = AVEE - AVDD
+	 * 2 = AVEE + VCL - AVDD
+	 * 3 = AVEE x 2 - AVDD
+	 * The defaults are 3 and 2 yielding 0x32
+	 */
+	u8 bt5ctr[NT35510_P1_BT5CTR_LEN];
+	/**
+	 * @vgp: setting for VGP, the positive gamma divider voltages
+	 * VGMP the high voltage and VGSP the low voltage.
+	 * The first byte contains bit 8 of VGMP and VGSP in bits 4 and 0
+	 * The second byte contains bit 0..7 of VGMP
+	 * The third byte contains bit 0..7 of VGSP
+	 * VGMP 0x00 = 3.0V .. 0x108 = 6.3V in steps of 12.5mV
+	 * VGSP 0x00 = 0V .. 0x111 = 3.7V in steps of 12.5mV
+	 */
+	u8 vgp[NT35510_P1_VGP_LEN];
+	/**
+	 * @vgn: setting for VGN, the negative gamma divider voltages,
+	 * same layout of bytes as @vgp.
+	 */
+	u8 vgn[NT35510_P1_VGN_LEN];
+	/**
+	 * @sdeqctr: Source driver control settings, first byte is
+	 * 0 for mode 1 and 1 for mode 2. Mode 1 uses two steps and
+	 * mode 2 uses three steps meaning EQS3 is not used in mode
+	 * 1. Mode 2 is default. The last three parameters are EQS1, EQS2
+	 * and EQS3, setting the rise time for each equalizer step:
+	 * 0x00 = 0.0 us to 0x0f = 7.5 us in steps of 0.5us. The default
+	 * is 0x07 = 3.5 us.
+	 */
+	u8 sdeqctr[NT35510_P0_SDEQCTR_LEN];
+	/**
+	 * @sdvpctr: power/voltage behaviour during vertical porch time
+	 */
+	u8 sdvpctr;
+	/**
+	 * @t1: the number of pixel clocks on one scanline, range
+	 * 0x100 (258 ticks) .. 0x3FF (1024 ticks) so the value + 1
+	 * clock ticks.
+	 */
+	u16 t1;
+	/**
+	 * @vbp: vertical back porch toward the PANEL note: not toward
+	 * the DSI host; these are separate interfaces, in from DSI host
+	 * and out to the panel.
+	 */
+	u8 vbp;
+	/**
+	 * @vfp: vertical front porch toward the PANEL.
+	 */
+	u8 vfp;
+	/**
+	 * @psel: pixel clock divisor: 0 = 1, 1 = 2, 2 = 4, 3 = 8.
+	 */
+	u8 psel;
+	/**
+	 * @dpmctr12: Display timing control 12
+	 * Byte 1 bit 4 selects LVGL voltage level: 0 = VGLX, 1 = VGL_REG
+	 * Byte 1 bit 1 selects gate signal mode: 0 = non-overlap, 1 = overlap
+	 * Byte 1 bit 0 selects output signal control R/L swap, 0 = normal
+	 * 1 = swap all O->E, L->R
+	 * Byte 2 is CLW delay clock for CK O/E and CKB O/E signals:
+	 * 0x00 = 0us .. 0xFF = 12.75us in 0.05us steps
+	 * Byte 3 is FTI_H0 delay time for STP O/E signals:
+	 * 0x00 = 0us .. 0xFF = 12.75us in 0.05us steps
+	 */
+	u8 dpmctr12[NT35510_P0_DPMCTR12_LEN];
+	/**
+	 * @gamma_corr_pos_r: Red gamma correction parameters, positive
+	 */
+	u8 gamma_corr_pos_r[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_pos_g: Green gamma correction parameters, positive
+	 */
+	u8 gamma_corr_pos_g[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_pos_b: Blue gamma correction parameters, positive
+	 */
+	u8 gamma_corr_pos_b[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_neg_r: Red gamma correction parameters, negative
+	 */
+	u8 gamma_corr_neg_r[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_neg_g: Green gamma correction parameters, negative
+	 */
+	u8 gamma_corr_neg_g[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_neg_b: Blue gamma correction parameters, negative
+	 */
+	u8 gamma_corr_neg_b[NT35510_P1_GAMMA_LEN];
+};
+
+/**
+ * struct nt35510 - state container for the NT35510 panel
+ */
+struct nt35510 {
+	/**
+	 * @dev: the container device
+	 */
+	struct device *dev;
+	/**
+	 * @conf: the specific panel configuration, as the NT35510
+	 * can be combined with many physical panels, they can have
+	 * different physical dimensions and gamma correction etc,
+	 * so this is stored in the config.
+	 */
+	const struct nt35510_config *conf;
+	/**
+	 * @panel: the DRM panel object for the instance
+	 */
+	struct drm_panel panel;
+	/**
+	 * @supplies: regulators supplying the panel
+	 */
+	struct regulator_bulk_data supplies[2];
+	/**
+	 * @reset_gpio: the reset line
+	 */
+	struct gpio_desc *reset_gpio;
+};
+
+/* Manufacturer command has strictly this byte sequence */
+static const u8 nt35510_mauc_select_page_0[] = { 0x55, 0xAA, 0x52, 0x08, 0x00 };
+static const u8 nt35510_mauc_select_page_1[] = { 0x55, 0xAA, 0x52, 0x08, 0x01 };
+static const u8 nt35510_vgh_on[] = { 0x01 };
+
+static inline struct nt35510 *panel_to_nt35510(struct drm_panel *panel)
+{
+	return container_of(panel, struct nt35510, panel);
+}
+
+#define NT35510_ROTATE_0_SETTING	0x02
+#define NT35510_ROTATE_180_SETTING	0x00
+
+static int nt35510_send_long(struct nt35510 *nt, struct mipi_dsi_device *dsi,
+			     u8 cmd, u8 cmdlen, const u8 *seq)
+{
+	const u8 *seqp = seq;
+	int cmdwritten = 0;
+	int chunk = cmdlen;
+	int ret;
+
+	if (chunk > 15)
+		chunk = 15;
+	ret = mipi_dsi_dcs_write(dsi, cmd, seqp, chunk);
+	if (ret < 0) {
+		DRM_DEV_ERROR(nt->dev,
+			      "error sending DCS command seq cmd %02x\n",
+			      cmd);
+		return ret;
+	}
+	cmdwritten += chunk;
+	seqp += chunk;
+
+	while (cmdwritten < cmdlen) {
+		chunk = cmdlen - cmdwritten;
+		if (chunk > 15)
+			chunk = 15;
+		ret = mipi_dsi_generic_write(dsi, seqp, chunk);
+		if (ret < 0) {
+			DRM_DEV_ERROR(nt->dev,
+				      "error sending generic write seq %02x\n",
+				      cmd);
+			return ret;
+		}
+		cmdwritten += chunk;
+		seqp += chunk;
+	}
+	DRM_DEV_DEBUG(nt->dev, "sent command %02x %02x bytes\n",
+		      cmd, cmdlen);
+	return 0;
+}
+
+static int nt35510_read_id(struct nt35510 *nt)
+{
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	u8 id1, id2, id3;
+	int ret;
+
+	ret = mipi_dsi_dcs_read(dsi, MCS_CMD_READ_ID1, &id1, 1);
+	if (ret < 0) {
+		DRM_DEV_ERROR(nt->dev, "could not read MTP ID1\n");
+		return ret;
+	}
+	ret = mipi_dsi_dcs_read(dsi, MCS_CMD_READ_ID2, &id2, 1);
+	if (ret < 0) {
+		DRM_DEV_ERROR(nt->dev, "could not read MTP ID2\n");
+		return ret;
+	}
+	ret = mipi_dsi_dcs_read(dsi, MCS_CMD_READ_ID3, &id3, 1);
+	if (ret < 0) {
+		DRM_DEV_ERROR(nt->dev, "could not read MTP ID3\n");
+		return ret;
+	}
+
+	/*
+	 * Multi-Time Programmable (?) memory contains manufacturer
+	 * ID (e.g. Hydis 0x55), driver ID (e.g. NT35510 0xc0) and
+	 * version.
+	 */
+	DRM_DEV_INFO(nt->dev,
+		     "MTP ID manufacturer: %02x version: %02x driver: %02x\n",
+		     id1, id2, id3);
+
+	return 0;
+}
+
+/**
+ * nt35510_setup_power() - set up power config in page 1
+ * @nt: the display instance to set up
+ */
+static int nt35510_setup_power(struct nt35510 *nt)
+{
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	int ret;
+
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETAVDD,
+				NT35510_P1_AVDD_LEN,
+				nt->conf->avdd);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT1CTR,
+				NT35510_P1_BT1CTR_LEN,
+				nt->conf->bt1ctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETAVEE,
+				NT35510_P1_AVEE_LEN,
+				nt->conf->avee);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT2CTR,
+				NT35510_P1_BT2CTR_LEN,
+				nt->conf->bt2ctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGH,
+				NT35510_P1_VGH_LEN,
+				nt->conf->vgh);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT4CTR,
+				NT35510_P1_BT4CTR_LEN,
+				nt->conf->bt4ctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_VGHCTR,
+				ARRAY_SIZE(nt35510_vgh_on),
+				nt35510_vgh_on);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGL,
+				NT35510_P1_VGL_LEN,
+				nt->conf->vgl);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT5CTR,
+				NT35510_P1_BT5CTR_LEN,
+				nt->conf->bt5ctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGP,
+				NT35510_P1_VGP_LEN,
+				nt->conf->vgp);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGN,
+				NT35510_P1_VGN_LEN,
+				nt->conf->vgn);
+	if (ret)
+		return ret;
+
+	/* Typically 10 ms */
+	usleep_range(10000, 20000);
+
+	return 0;
+}
+
+/**
+ * nt35510_setup_display() - set up display config in page 0
+ * @nt: the display instance to set up
+ */
+static int nt35510_setup_display(struct nt35510 *nt)
+{
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	const struct nt35510_config *conf = nt->conf;
+	u8 dopctr[NT35510_P0_DOPCTR_LEN];
+	u8 gseqctr[NT35510_P0_GSEQCTR_LEN];
+	u8 dpfrctr[NT35510_P0_DPFRCTR1_LEN];
+	/* FIXME: set up any rotation (assume none for now) */
+	u8 addr_mode = NT35510_ROTATE_0_SETTING;
+	u8 val;
+	int ret;
+
+	/* Enable TE, EoTP and RGB pixel format */
+	dopctr[0] = NT35510_DOPCTR_0_DSITE | NT35510_DOPCTR_0_EOTP |
+		NT35510_DOPCTR_0_N565;
+	dopctr[1] = NT35510_DOPCTR_1_CTB;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DOPCTR,
+				NT35510_P0_DOPCTR_LEN,
+				dopctr);
+	if (ret)
+		return ret;
+
+	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_ADDRESS_MODE, &addr_mode,
+				 sizeof(addr_mode));
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Source data hold time, default 0x05 = 2.5us
+	 * 0x00..0x3F = 0 .. 31.5us in steps of 0.5us
+	 * 0x0A = 5us
+	 */
+	val = 0x0A;
+	ret = mipi_dsi_dcs_write(dsi, NT35510_P0_SDHDTCTR, &val,
+				 sizeof(val));
+	if (ret < 0)
+		return ret;
+
+	/* EQ control for gate signals, 0x00 = 0 us */
+	gseqctr[0] = 0x00;
+	gseqctr[1] = 0x00;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_GSEQCTR,
+				NT35510_P0_GSEQCTR_LEN,
+				gseqctr);
+	if (ret)
+		return ret;
+
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_SDEQCTR,
+				NT35510_P0_SDEQCTR_LEN,
+				conf->sdeqctr);
+	if (ret)
+		return ret;
+
+	ret = mipi_dsi_dcs_write(dsi, NT35510_P0_SDVPCTR,
+				 &conf->sdvpctr, 1);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Display timing control for active and idle off mode:
+	 * the first byte contains
+	 * the two high bits of T1A and second byte the low 8 bits, and
+	 * the valid range is 0x100 (257) to 0x3ff (1023) representing
+	 * 258..1024 (+1) pixel clock ticks for one scanline. At 20MHz pixel
+	 * clock this covers the range of 12.90us .. 51.20us in steps of
+	 * 0.05us, the default is 0x184 (388) representing 389 ticks.
+	 * The third byte is VBPDA, vertical back porch display active
+	 * and the fourth VFPDA, vertical front porch display active,
+	 * both given in number of scanlines in the range 0x02..0xff
+	 * for 2..255 scanlines. The fifth byte is 2 bits selecting
+	 * PSEL for active and idle off mode, how much the 20MHz clock
+	 * is divided by 0..3.  This needs to be adjusted to get the right
+	 * frame rate.
+	 */
+	dpfrctr[0] = (conf->t1 >> 8) & 0xFF;
+	dpfrctr[1] = conf->t1 & 0xFF;
+	/* Vertical back porch */
+	dpfrctr[2] = conf->vbp;
+	/* Vertical front porch */
+	dpfrctr[3] = conf->vfp;
+	dpfrctr[4] = conf->psel;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPFRCTR1,
+				NT35510_P0_DPFRCTR1_LEN,
+				dpfrctr);
+	if (ret)
+		return ret;
+	/* For idle and partial idle off mode we decrease front porch by one */
+	dpfrctr[3]--;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPFRCTR2,
+				NT35510_P0_DPFRCTR2_LEN,
+				dpfrctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPFRCTR3,
+				NT35510_P0_DPFRCTR3_LEN,
+				dpfrctr);
+	if (ret)
+		return ret;
+
+	/* Enable TE on vblank */
+	ret = mipi_dsi_dcs_set_tear_on(dsi, MIPI_DSI_DCS_TEAR_MODE_VBLANK);
+	if (ret)
+		return ret;
+
+	/* Turn on the pads? */
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPMCTR12,
+				NT35510_P0_DPMCTR12_LEN,
+				conf->dpmctr12);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int nt35510_set_brightness(struct backlight_device *bl)
+{
+	struct nt35510 *nt = bl_get_data(bl);
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	u8 brightness = bl->props.brightness;
+	int ret;
+
+	DRM_DEV_DEBUG(nt->dev, "set brightness %d\n", brightness);
+	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
+				 &brightness,
+				 sizeof(brightness));
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static const struct backlight_ops nt35510_bl_ops = {
+	.update_status = nt35510_set_brightness,
+};
+
+/*
+ * This power-on sequence
+ */
+static int nt35510_power_on(struct nt35510 *nt)
+{
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(nt->supplies), nt->supplies);
+	if (ret < 0) {
+		dev_err(nt->dev, "unable to enable regulators\n");
+		return ret;
+	}
+
+	/* Toggle RESET in accordance with datasheet page 370 */
+	if (nt->reset_gpio) {
+		gpiod_set_value(nt->reset_gpio, 1);
+		/* Active min 10 us according to datasheet, let's say 20 */
+		usleep_range(20, 1000);
+		gpiod_set_value(nt->reset_gpio, 0);
+		/*
+		 * 5 ms during sleep mode, 120 ms during sleep out mode
+		 * according to datasheet, let's use 120-140 ms.
+		 */
+		usleep_range(120000, 140000);
+	}
+
+	ret = nt35510_read_id(nt);
+	if (ret)
+		return ret;
+
+	/* Set up stuff in  manufacturer control, page 1 */
+	ret = nt35510_send_long(nt, dsi, MCS_CMD_MAUCCTR,
+				ARRAY_SIZE(nt35510_mauc_select_page_1),
+				nt35510_mauc_select_page_1);
+	if (ret)
+		return ret;
+
+	ret = nt35510_setup_power(nt);
+	if (ret)
+		return ret;
+
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_RED_POS,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_pos_r);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_GREEN_POS,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_pos_g);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_BLUE_POS,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_pos_b);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_RED_NEG,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_neg_r);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_GREEN_NEG,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_neg_g);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_BLUE_NEG,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_neg_b);
+	if (ret)
+		return ret;
+
+	/* Set up stuff in  manufacturer control, page 0 */
+	ret = nt35510_send_long(nt, dsi, MCS_CMD_MAUCCTR,
+				ARRAY_SIZE(nt35510_mauc_select_page_0),
+				nt35510_mauc_select_page_0);
+	if (ret)
+		return ret;
+
+	ret = nt35510_setup_display(nt);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int nt35510_power_off(struct nt35510 *nt)
+{
+	int ret;
+
+	ret = regulator_bulk_disable(ARRAY_SIZE(nt->supplies), nt->supplies);
+	if (ret)
+		return ret;
+
+	if (nt->reset_gpio)
+		gpiod_set_value(nt->reset_gpio, 1);
+
+	return 0;
+}
+
+static int nt35510_unprepare(struct drm_panel *panel)
+{
+	struct nt35510 *nt = panel_to_nt35510(panel);
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	int ret;
+
+	ret = mipi_dsi_dcs_set_display_off(dsi);
+	if (ret) {
+		DRM_DEV_ERROR(nt->dev, "failed to turn display off (%d)\n",
+			      ret);
+		return ret;
+	}
+	usleep_range(10000, 20000);
+
+	/* Enter sleep mode */
+	ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
+	if (ret) {
+		DRM_DEV_ERROR(nt->dev, "failed to enter sleep mode (%d)\n",
+			      ret);
+		return ret;
+	}
+
+	/* Wait 4 frames, how much is that 5ms in the vendor driver */
+	usleep_range(5000, 10000);
+
+	ret = nt35510_power_off(nt);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int nt35510_prepare(struct drm_panel *panel)
+{
+	struct nt35510 *nt = panel_to_nt35510(panel);
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	int ret;
+
+	ret = nt35510_power_on(nt);
+	if (ret)
+		return ret;
+
+	/* Exit sleep mode */
+	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
+	if (ret) {
+		DRM_DEV_ERROR(nt->dev, "failed to exit sleep mode (%d)\n",
+			      ret);
+		return ret;
+	}
+	/* Up to 120 ms */
+	usleep_range(120000, 150000);
+
+	ret = mipi_dsi_dcs_set_display_on(dsi);
+	if (ret) {
+		DRM_DEV_ERROR(nt->dev, "failed to turn display on (%d)\n",
+			      ret);
+		return ret;
+	}
+	/* Some 10 ms */
+	usleep_range(10000, 20000);
+
+	return 0;
+}
+
+static int nt35510_get_modes(struct drm_panel *panel,
+			     struct drm_connector *connector)
+{
+	struct nt35510 *nt = panel_to_nt35510(panel);
+	struct drm_display_mode *mode;
+	struct drm_display_info *info;
+
+	info = &connector->display_info;
+	info->width_mm = nt->conf->width_mm;
+	info->height_mm = nt->conf->height_mm;
+	mode = drm_mode_duplicate(connector->dev, &nt->conf->mode);
+	if (!mode) {
+		DRM_ERROR("bad mode or failed to add mode\n");
+		return -EINVAL;
+	}
+	drm_mode_set_name(mode);
+	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
+
+	mode->width_mm = nt->conf->width_mm;
+	mode->height_mm = nt->conf->height_mm;
+	drm_mode_probed_add(connector, mode);
+
+	return 1; /* Number of modes */
+}
+
+static const struct drm_panel_funcs nt35510_drm_funcs = {
+	.unprepare = nt35510_unprepare,
+	.prepare = nt35510_prepare,
+	.get_modes = nt35510_get_modes,
+};
+
+static int nt35510_probe(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct nt35510 *nt;
+	int ret;
+
+	nt = devm_kzalloc(dev, sizeof(struct nt35510), GFP_KERNEL);
+	if (!nt)
+		return -ENOMEM;
+	mipi_dsi_set_drvdata(dsi, nt);
+	nt->dev = dev;
+
+	dsi->lanes = 2;
+	dsi->format = MIPI_DSI_FMT_RGB888;
+	/*
+	 * Datasheet suggests max HS rate for NT35510 is 250 MHz
+	 * (period time 4ns, see figure 7.6.4 page 365) and max LP rate is
+	 * 20 MHz (period time 50ns, see figure 7.6.6. page 366).
+	 * However these frequencies appear in source code for the Hydis
+	 * HVA40WV1 panel and setting up the LP frequency makes the panel
+	 * not work.
+	 *
+	 * TODO: if other panels prove to be closer to the datasheet,
+	 * maybe make this a per-panel config in struct nt35510_config?
+	 */
+	dsi->hs_rate = 349440000;
+	dsi->lp_rate = 9600000;
+	dsi->mode_flags = MIPI_DSI_CLOCK_NON_CONTINUOUS |
+		MIPI_DSI_MODE_EOT_PACKET;
+
+	/*
+	 * Every new incarnation of this display must have a unique
+	 * data entry for the system in this driver.
+	 */
+	nt->conf = of_device_get_match_data(dev);
+	if (!nt->conf) {
+		dev_err(dev, "missing device configuration\n");
+		return -ENODEV;
+	}
+
+	nt->supplies[0].supply = "vdd"; /* 2.3-4.8 V */
+	nt->supplies[1].supply = "vddi"; /* 1.65-3.3V */
+	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(nt->supplies),
+				      nt->supplies);
+	if (ret < 0)
+		return ret;
+	ret = regulator_set_voltage(nt->supplies[0].consumer,
+				    2300000, 4800000);
+	if (ret)
+		return ret;
+	ret = regulator_set_voltage(nt->supplies[1].consumer,
+				    1650000, 3300000);
+	if (ret)
+		return ret;
+
+	nt->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_ASIS);
+	if (IS_ERR(nt->reset_gpio)) {
+		dev_err(dev, "error getting RESET GPIO\n");
+		return PTR_ERR(nt->reset_gpio);
+	}
+
+	drm_panel_init(&nt->panel, dev, &nt35510_drm_funcs,
+		       DRM_MODE_CONNECTOR_DSI);
+
+	/*
+	 * First, try to locate an external backlight (such as on GPIO)
+	 * if this fails, assume we will want to use the internal backlight
+	 * control.
+	 */
+	ret = drm_panel_of_backlight(&nt->panel);
+	if (ret) {
+		dev_err(dev, "error getting external backlight %d\n", ret);
+		return ret;
+	}
+	if (!nt->panel.backlight) {
+		struct backlight_device *bl;
+
+		bl = devm_backlight_device_register(dev, "nt35510", dev, nt,
+						    &nt35510_bl_ops, NULL);
+		if (IS_ERR(bl)) {
+			DRM_DEV_ERROR(dev, "failed to register backlight device\n");
+			return PTR_ERR(bl);
+		}
+		bl->props.max_brightness = 255;
+		bl->props.brightness = 255;
+		bl->props.power = FB_BLANK_POWERDOWN;
+		nt->panel.backlight = bl;
+	}
+
+	ret = drm_panel_add(&nt->panel);
+	if (ret < 0)
+		return ret;
+
+	ret = mipi_dsi_attach(dsi);
+	if (ret < 0)
+		drm_panel_remove(&nt->panel);
+
+	return 0;
+}
+
+static int nt35510_remove(struct mipi_dsi_device *dsi)
+{
+	struct nt35510 *nt = mipi_dsi_get_drvdata(dsi);
+	int ret;
+
+	mipi_dsi_detach(dsi);
+	/* Power off */
+	ret = nt35510_power_off(nt);
+	drm_panel_remove(&nt->panel);
+
+	return ret;
+}
+
+/*
+ * These gamma correction values are 10bit tuples, so only bits 0 and 1 is
+ * ever used in the first byte. They form a positive and negative gamma
+ * correction curve for each color, values must be strictly higher for each
+ * step on the curve. As can be seen these default curves goes from 0x0001
+ * to 0x03FE.
+ */
+#define NT35510_GAMMA_POS_DEFAULT 0x00, 0x01, 0x00, 0x43, 0x00, \
+		0x6B, 0x00, 0x87, 0x00, 0xA3, 0x00, 0xCE, 0x00, 0xF1, 0x01, \
+		0x27, 0x01, 0x53, 0x01, 0x98, 0x01, 0xCE, 0x02, 0x22, 0x02, \
+		0x83, 0x02, 0x78, 0x02, 0x9E, 0x02, 0xDD, 0x03, 0x00, 0x03, \
+		0x2E, 0x03, 0x54, 0x03, 0x7F, 0x03, 0x95, 0x03, 0xB3, 0x03, \
+		0xC2, 0x03, 0xE1, 0x03, 0xF1, 0x03, 0xFE
+
+#define NT35510_GAMMA_NEG_DEFAULT 0x00, 0x01, 0x00, 0x43, 0x00, \
+		0x6B, 0x00, 0x87, 0x00, 0xA3, 0x00, 0xCE, 0x00, 0xF1, 0x01, \
+		0x27, 0x01, 0x53, 0x01, 0x98, 0x01, 0xCE, 0x02, 0x22, 0x02, \
+		0x43, 0x02, 0x50, 0x02, 0x9E, 0x02, 0xDD, 0x03, 0x00, 0x03, \
+		0x2E, 0x03, 0x54, 0x03, 0x7F, 0x03, 0x95, 0x03, 0xB3, 0x03, \
+		0xC2, 0x03, 0xE1, 0x03, 0xF1, 0x03, 0xFE
+
+/*
+ * The Hydis HVA40WV1 panel
+ */
+static const struct nt35510_config nt35510_hydis_hva40wv1 = {
+	.width_mm = 52,
+	.height_mm = 86,
+	/**
+	 * As the Hydis panel is used in command mode, the porches etc
+	 * are settings programmed internally into the NT35510 controller
+	 * and generated toward the physical display. As the panel is not
+	 * used in video mode, these are not really exposed to the DSI
+	 * host.
+	 *
+	 * Display frame rate control:
+	 * Frame rate = (20 MHz / 1) / (389 * (7 + 50 + 800)) ~= 60 Hz
+	 */
+	.mode = {
+		/* The internal pixel clock of the NT35510 is 20 MHz */
+		.clock = 20000000,
+		.hdisplay = 480,
+		.hsync_start = 480 + 2, /* HFP = 2 */
+		.hsync_end = 480 + 2 + 0, /* HSync = 0 */
+		.htotal = 480 + 2 + 0 + 5, /* HFP = 5 */
+		.vdisplay = 800,
+		.vsync_start = 800 + 2, /* VFP = 2 */
+		.vsync_end = 800 + 2 + 0, /* VSync = 0 */
+		.vtotal = 800 + 2 + 0 + 5, /* VBP = 5 */
+		.vrefresh = 60, /* Calculated */
+		.flags = 0,
+	},
+	/* 0x09: AVDD = 5.6V */
+	.avdd = { 0x09, 0x09, 0x09 },
+	/* 0x34: PCK = Hsync/2, BTP = 2 x VDDB */
+	.bt1ctr = { 0x34, 0x34, 0x34 },
+	/* 0x09: AVEE = -5.6V */
+	.avee = { 0x09, 0x09, 0x09 },
+	/* 0x24: NCK = Hsync/2, BTN =  -2 x VDDB */
+	.bt2ctr = { 0x24, 0x24, 0x24 },
+	/* 0x05 = 12V */
+	.vgh = { 0x05, 0x05, 0x05 },
+	/* 0x24: NCKA = Hsync/2, VGH = 2 x AVDD - AVEE */
+	.bt4ctr = { 0x24, 0x24, 0x24 },
+	/* 0x0B = -13V */
+	.vgl = { 0x0B, 0x0B, 0x0B },
+	/* 0x24: LCKA = Hsync, VGL = AVDD + VCL - AVDD */
+	.bt5ctr = { 0x24, 0x24, 0x24 },
+	/* VGMP: 0x0A3 = 5.0375V, VGSP = 0V */
+	.vgp = { 0x00, 0xA3, 0x00 },
+	/* VGMP: 0x0A3 = 5.0375V, VGSP = 0V */
+	.vgn = { 0x00, 0xA3, 0x00 },
+	/* SDEQCTR: source driver EQ mode 2, 2.5 us rise time on each step */
+	.sdeqctr = { 0x01, 0x05, 0x05, 0x05 },
+	/* SDVPCTR: Normal operation off color during v porch */
+	.sdvpctr = 0x01,
+	/* T1: number of pixel clocks on one scanline: 0x184 = 389 clocks */
+	.t1 = 0x0184,
+	/* VBP: vertical back porch toward the panel */
+	.vbp = 7,
+	/* VFP: vertical front porch toward the panel */
+	.vfp = 50,
+	/* PSEL: divide pixel clock 20MHz with 1 (no clock downscaling) */
+	.psel = 0,
+	/* DPTMCTR12: 0x03: LVGL = VGLX, overlap mode, swap R->L O->E */
+	.dpmctr12 = { 0x03, 0x00, 0x00, },
+	/* Default gamma correction values */
+	.gamma_corr_pos_r = { NT35510_GAMMA_POS_DEFAULT },
+	.gamma_corr_pos_g = { NT35510_GAMMA_POS_DEFAULT },
+	.gamma_corr_pos_b = { NT35510_GAMMA_POS_DEFAULT },
+	.gamma_corr_neg_r = { NT35510_GAMMA_NEG_DEFAULT },
+	.gamma_corr_neg_g = { NT35510_GAMMA_NEG_DEFAULT },
+	.gamma_corr_neg_b = { NT35510_GAMMA_NEG_DEFAULT },
+};
+
+static const struct of_device_id nt35510_of_match[] = {
+	{
+		.compatible = "hydis,hva40wv1",
+		.data = &nt35510_hydis_hva40wv1,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, nt35510_of_match);
+
+static struct mipi_dsi_driver nt35510_driver = {
+	.probe = nt35510_probe,
+	.remove = nt35510_remove,
+	.driver = {
+		.name = "panel-novatek-nt35510",
+		.of_match_table = nt35510_of_match,
+	},
+};
+module_mipi_dsi_driver(nt35510_driver);
+
+MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
+MODULE_DESCRIPTION("NT35510-based panel driver");
+MODULE_LICENSE("GPL v2");
-- 
2.21.1

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Re: [PATCH 3/3 v2] drm/panel: Add driver for Novatek NT35510-based panels

[Sam Ravnborg]

On Sun, Feb 23, 2020 at 01:18:41PM +0100, Linus Walleij wrote:
> This adds a driver for panels based on the Novatek NT35510
> display driver IC, such as the Hydis HVA40WV1 panel found
> in the Samsung GT-S7710.
> 
> The NT35510 can be used with both internal and external
> backlight (such as GPIO backlight) so we support both:
> if no external backlight is found, we register a subdriver
> for the internal backlight.
> 
> Cc: Stephan Gerhold <stephan@gerhold.net>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Applied to drm-misc-next.

	Sam

> ---
> ChangeLog v1->v2:
> - Rebase onto v5.6-rc1
> - Account for changes in the panel struct and get_modes()
>   passing the connector as argument.
> - Use specific full filename for the panel driver.
> - Update to match rename of DT binding file.
> - Drop select VIDEO_MODE_HELPERS
> - Fix spelling errors and stray characters, call 4bit groups
>   nibbles rather than nybbles
> - Alphabetize includes and order them as requested by Sam
> - Drop the surplus videomode includes
> - Drop any backlight handling from .enable() and .disable()
>   callbacks and rely on the backlight handling in the DRM
>   panel core, but still assign a backlight from within the
>   driver if we don't find one in the device tree.
> ---
>  MAINTAINERS                                   |    7 +
>  drivers/gpu/drm/panel/Kconfig                 |   10 +
>  drivers/gpu/drm/panel/Makefile                |    1 +
>  drivers/gpu/drm/panel/panel-novatek-nt35510.c | 1098 +++++++++++++++++
>  4 files changed, 1116 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-novatek-nt35510.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 17f502467c8a..8e7433d74530 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5322,6 +5322,13 @@ F:	drivers/gpu/drm/msm/
>  F:	include/uapi/drm/msm_drm.h
>  F:	Documentation/devicetree/bindings/display/msm/
>  
> +DRM DRIVER FOR NOVATEK NT35510 PANELS
> +M:	Linus Walleij <linus.walleij@linaro.org>
> +T:	git git://anongit.freedesktop.org/drm/drm-misc
> +S:	Maintained
> +F:	drivers/gpu/drm/panel/panel-novatek-nt35510.c
> +F:	Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
> +
>  DRM DRIVER FOR NVIDIA GEFORCE/QUADRO GPUS
>  M:	Ben Skeggs <bskeggs@redhat.com>
>  L:	dri-devel@lists.freedesktop.org
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 19eac3d799a7..b37495a5acce 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -149,6 +149,16 @@ config DRM_PANEL_NEC_NL8048HL11
>  	  panel (found on the Zoom2/3/3630 SDP boards). To compile this driver
>  	  as a module, choose M here.
>  
> +config DRM_PANEL_NOVATEK_NT35510
> +	tristate "Novatek NT35510 RGB panel driver"
> +	depends on OF
> +	depends on DRM_MIPI_DSI
> +	depends on BACKLIGHT_CLASS_DEVICE
> +	help
> +	  Say Y here if you want to enable support for the panels built
> +	  around the Novatek NT35510 display controller, such as some
> +	  Hydis panels.
> +
>  config DRM_PANEL_NOVATEK_NT39016
>  	tristate "Novatek NT39016 RGB/SPI panel"
>  	depends on OF && SPI
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index c4ca0e3b9b3c..7bc8a57ede2b 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -13,6 +13,7 @@ obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK500HD1829) += panel-leadtek-ltk500hd1829.o
>  obj-$(CONFIG_DRM_PANEL_LG_LB035Q02) += panel-lg-lb035q02.o
>  obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
>  obj-$(CONFIG_DRM_PANEL_NEC_NL8048HL11) += panel-nec-nl8048hl11.o
> +obj-$(CONFIG_DRM_PANEL_NOVATEK_NT35510) += panel-novatek-nt35510.o
>  obj-$(CONFIG_DRM_PANEL_NOVATEK_NT39016) += panel-novatek-nt39016.o
>  obj-$(CONFIG_DRM_PANEL_OLIMEX_LCD_OLINUXINO) += panel-olimex-lcd-olinuxino.o
>  obj-$(CONFIG_DRM_PANEL_ORISETECH_OTM8009A) += panel-orisetech-otm8009a.o
> diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35510.c b/drivers/gpu/drm/panel/panel-novatek-nt35510.c
> new file mode 100644
> index 000000000000..b4c014126781
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-novatek-nt35510.c
> @@ -0,0 +1,1098 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Novatek NT35510 panel driver
> + * Copyright (C) 2020 Linus Walleij <linus.walleij@linaro.org>
> + * Based on code by Robert Teather (C) 2012 Samsung
> + *
> + * This display driver (and I refer to the physical component NT35510,
> + * not this Linux kernel software driver) can handle:
> + * 480x864, 480x854, 480x800, 480x720 and 480x640 pixel displays.
> + * It has 480x840x24bit SRAM embedded for storing a frame.
> + * When powered on the display is by default in 480x800 mode.
> + *
> + * The actual panels using this component have different names, but
> + * the code needed to set up and configure the panel will be similar,
> + * so they should all use the NT35510 driver with appropriate configuration
> + * per-panel, e.g. for physical size.
> + *
> + * This driver is for the DSI interface to panels using the NT35510.
> + *
> + * The NT35510 can also use an RGB (DPI) interface combined with an
> + * I2C or SPI interface for setting up the NT35510. If this is needed
> + * this panel driver should be refactored to also support that use
> + * case.
> + */
> +#include <linux/backlight.h>
> +#include <linux/bitops.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/regmap.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>
> +#include <drm/drm_print.h>
> +
> +#define MCS_CMD_MAUCCTR		0xF0 /* Manufacturer command enable */
> +#define MCS_CMD_READ_ID1	0xDA
> +#define MCS_CMD_READ_ID2	0xDB
> +#define MCS_CMD_READ_ID3	0xDC
> +#define MCS_CMD_MTP_READ_SETTING 0xF8 /* Uncertain about name */
> +#define MCS_CMD_MTP_READ_PARAM 0xFF /* Uncertain about name */
> +
> +/*
> + * These manufacturer commands are available after we enable manufacturer
> + * command set (MCS) for page 0.
> + */
> +#define NT35510_P0_DOPCTR 0xB1
> +#define NT35510_P0_SDHDTCTR 0xB6
> +#define NT35510_P0_GSEQCTR 0xB7
> +#define NT35510_P0_SDEQCTR 0xB8
> +#define NT35510_P0_SDVPCTR 0xBA
> +#define NT35510_P0_DPFRCTR1 0xBD
> +#define NT35510_P0_DPFRCTR2 0xBE
> +#define NT35510_P0_DPFRCTR3 0xBF
> +#define NT35510_P0_DPMCTR12 0xCC
> +
> +#define NT35510_P0_DOPCTR_LEN 2
> +#define NT35510_P0_GSEQCTR_LEN 2
> +#define NT35510_P0_SDEQCTR_LEN 4
> +#define NT35510_P0_SDVPCTR_LEN 1
> +#define NT35510_P0_DPFRCTR1_LEN 5
> +#define NT35510_P0_DPFRCTR2_LEN 5
> +#define NT35510_P0_DPFRCTR3_LEN 5
> +#define NT35510_P0_DPMCTR12_LEN 3
> +
> +#define NT35510_DOPCTR_0_RAMKP BIT(7) /* Contents kept in sleep */
> +#define NT35510_DOPCTR_0_DSITE BIT(6) /* Enable TE signal */
> +#define NT35510_DOPCTR_0_DSIG BIT(5) /* Enable generic read/write */
> +#define NT35510_DOPCTR_0_DSIM BIT(4) /* Enable video mode on DSI */
> +#define NT35510_DOPCTR_0_EOTP BIT(3) /* Support EoTP */
> +#define NT35510_DOPCTR_0_N565 BIT(2) /* RGB or BGR pixel format */
> +#define NT35510_DOPCTR_1_TW_PWR_SEL BIT(4) /* TE power selector */
> +#define NT35510_DOPCTR_1_CRGB BIT(3) /* RGB or BGR byte order */
> +#define NT35510_DOPCTR_1_CTB BIT(2) /* Vertical scanning direction */
> +#define NT35510_DOPCTR_1_CRL BIT(1) /* Source driver data shift */
> +#define NT35510_P0_SDVPCTR_PRG BIT(2) /* 0 = normal operation, 1 = VGLO */
> +#define NT35510_P0_SDVPCTR_AVDD 0 /* source driver output = AVDD */
> +#define NT35510_P0_SDVPCTR_OFFCOL 1 /* source driver output = off color */
> +#define NT35510_P0_SDVPCTR_AVSS 2 /* source driver output = AVSS */
> +#define NT35510_P0_SDVPCTR_HI_Z 3 /* source driver output = High impedance */
> +
> +/*
> + * These manufacturer commands are available after we enable manufacturer
> + * command set (MCS) for page 1.
> + */
> +#define NT35510_P1_SETAVDD 0xB0
> +#define NT35510_P1_SETAVEE 0xB1
> +#define NT35510_P1_SETVCL 0xB2
> +#define NT35510_P1_SETVGH 0xB3
> +#define NT35510_P1_SETVRGH 0xB4
> +#define NT35510_P1_SETVGL 0xB5
> +#define NT35510_P1_BT1CTR 0xB6
> +#define NT35510_P1_BT2CTR 0xB7
> +#define NT35510_P1_BT3CTR 0xB8
> +#define NT35510_P1_BT4CTR 0xB9 /* VGH boosting times/freq */
> +#define NT35510_P1_BT5CTR 0xBA
> +#define NT35510_P1_PFMCTR 0xBB
> +#define NT35510_P1_SETVGP 0xBC
> +#define NT35510_P1_SETVGN 0xBD
> +#define NT35510_P1_SETVCMOFF 0xBE
> +#define NT35510_P1_VGHCTR 0xBF /* VGH output ctrl */
> +#define NT35510_P1_SET_GAMMA_RED_POS 0xD1
> +#define NT35510_P1_SET_GAMMA_GREEN_POS 0xD2
> +#define NT35510_P1_SET_GAMMA_BLUE_POS 0xD3
> +#define NT35510_P1_SET_GAMMA_RED_NEG 0xD4
> +#define NT35510_P1_SET_GAMMA_GREEN_NEG 0xD5
> +#define NT35510_P1_SET_GAMMA_BLUE_NEG 0xD6
> +
> +/* AVDD and AVEE setting 3 bytes */
> +#define NT35510_P1_AVDD_LEN 3
> +#define NT35510_P1_AVEE_LEN 3
> +#define NT35510_P1_VGH_LEN 3
> +#define NT35510_P1_VGL_LEN 3
> +#define NT35510_P1_VGP_LEN 3
> +#define NT35510_P1_VGN_LEN 3
> +/* BT1CTR thru BT5CTR setting 3 bytes */
> +#define NT35510_P1_BT1CTR_LEN 3
> +#define NT35510_P1_BT2CTR_LEN 3
> +#define NT35510_P1_BT4CTR_LEN 3
> +#define NT35510_P1_BT5CTR_LEN 3
> +/* 52 gamma parameters times two per color: positive and negative */
> +#define NT35510_P1_GAMMA_LEN 52
> +
> +/**
> + * struct nt35510_config - the display-specific NT35510 configuration
> + *
> + * Some of the settings provide an array of bytes, A, B C which mean:
> + * A = normal / idle off mode
> + * B = idle on mode
> + * C = partial / idle off mode
> + *
> + * Gamma correction arrays are 10bit numbers, two consecutive bytes
> + * makes out one point on the gamma correction curve. The points are
> + * not linearly placed along the X axis, we get points 0, 1, 3, 5
> + * 7, 11, 15, 23, 31, 47, 63, 95, 127, 128, 160, 192, 208, 224, 232,
> + * 240, 244, 248, 250, 252, 254, 255. The voltages tuples form
> + * V0, V1, V3 ... V255, with 0x0000 being the lowest voltage and
> + * 0x03FF being the highest voltage.
> + *
> + * Each value must be strictly higher than the previous value forming
> + * a rising curve like this:
> + *
> + * ^
> + * |                                        V255
> + * |                                 V254
> + * |                         ....
> + * |                    V5
> + * |           V3
> + * |     V1
> + * | V0
> + * +------------------------------------------->
> + *
> + * The details about all settings can be found in the NT35510 Application
> + * Note.
> + */
> +struct nt35510_config {
> +	/**
> +	 * @width_mm: physical panel width [mm]
> +	 */
> +	u32 width_mm;
> +	/**
> +	 * @height_mm: physical panel height [mm]
> +	 */
> +	u32 height_mm;
> +	/**
> +	 * @mode: the display mode. This is only relevant outside the panel
> +	 * in video mode: in command mode this is configuring the internal
> +	 * timing in the display controller.
> +	 */
> +	const struct drm_display_mode mode;
> +	/**
> +	 * @avdd: setting for AVDD ranging from 0x00 = 6.5V to 0x14 = 4.5V
> +	 * in 0.1V steps the default is 0x05 which means 6.0V
> +	 */
> +	u8 avdd[NT35510_P1_AVDD_LEN];
> +	/**
> +	 * @bt1ctr: setting for boost power control for the AVDD step-up
> +	 * circuit (1)
> +	 * bits 0..2 in the lower nibble controls PCK, the booster clock
> +	 * frequency for the step-up circuit:
> +	 * 0 = Hsync/32
> +	 * 1 = Hsync/16
> +	 * 2 = Hsync/8
> +	 * 3 = Hsync/4
> +	 * 4 = Hsync/2
> +	 * 5 = Hsync
> +	 * 6 = Hsync x 2
> +	 * 7 = Hsync x 4
> +	 * bits 4..6 in the upper nibble controls BTP, the boosting
> +	 * amplification for the the step-up circuit:
> +	 * 0 = Disable
> +	 * 1 = 1.5 x VDDB
> +	 * 2 = 1.66 x VDDB
> +	 * 3 = 2 x VDDB
> +	 * 4 = 2.5 x VDDB
> +	 * 5 = 3 x VDDB
> +	 * The defaults are 4 and 4 yielding 0x44
> +	 */
> +	u8 bt1ctr[NT35510_P1_BT1CTR_LEN];
> +	/**
> +	 * @avee: setting for AVEE ranging from 0x00 = -6.5V to 0x14 = -4.5V
> +	 * in 0.1V steps the default is 0x05 which means -6.0V
> +	 */
> +	u8 avee[NT35510_P1_AVEE_LEN];
> +	/**
> +	 * @bt2ctr: setting for boost power control for the AVEE step-up
> +	 * circuit (2)
> +	 * bits 0..2 in the lower nibble controls NCK, the booster clock
> +	 * frequency, the values are the same as for PCK in @bt1ctr.
> +	 * bits 4..5 in the upper nibble controls BTN, the boosting
> +	 * amplification for the the step-up circuit.
> +	 * 0 = Disable
> +	 * 1 = -1.5 x VDDB
> +	 * 2 = -2 x VDDB
> +	 * 3 = -2.5 x VDDB
> +	 * 4 = -3 x VDDB
> +	 * The defaults are 4 and 3 yielding 0x34
> +	 */
> +	u8 bt2ctr[NT35510_P1_BT2CTR_LEN];
> +	/**
> +	 * @vgh: setting for VGH ranging from 0x00 = 7.0V to 0x0B = 18.0V
> +	 * in 1V steps, the default is 0x08 which means 15V
> +	 */
> +	u8 vgh[NT35510_P1_VGH_LEN];
> +	/**
> +	 * @bt4ctr: setting for boost power control for the VGH step-up
> +	 * circuit (4)
> +	 * bits 0..2 in the lower nibble controls HCK, the booster clock
> +	 * frequency, the values are the same as for PCK in @bt1ctr.
> +	 * bits 4..5 in the upper nibble controls BTH, the boosting
> +	 * amplification for the the step-up circuit.
> +	 * 0 = AVDD + VDDB
> +	 * 1 = AVDD - AVEE
> +	 * 2 = AVDD - AVEE + VDDB
> +	 * 3 = AVDD x 2 - AVEE
> +	 * The defaults are 4 and 3 yielding 0x34
> +	 */
> +	u8 bt4ctr[NT35510_P1_BT4CTR_LEN];
> +	/**
> +	 * @vgl: setting for VGL ranging from 0x00 = -2V to 0x0f = -15V in
> +	 * 1V steps, the default is 0x08 which means -10V
> +	 */
> +	u8 vgl[NT35510_P1_VGL_LEN];
> +	/**
> +	 * @bt5ctr: setting for boost power control for the VGL step-up
> +	 * circuit (5)
> +	 * bits 0..2 in the lower nibble controls LCK, the booster clock
> +	 * frequency, the values are the same as for PCK in @bt1ctr.
> +	 * bits 4..5 in the upper nibble controls BTL, the boosting
> +	 * amplification for the the step-up circuit.
> +	 * 0 = AVEE + VCL
> +	 * 1 = AVEE - AVDD
> +	 * 2 = AVEE + VCL - AVDD
> +	 * 3 = AVEE x 2 - AVDD
> +	 * The defaults are 3 and 2 yielding 0x32
> +	 */
> +	u8 bt5ctr[NT35510_P1_BT5CTR_LEN];
> +	/**
> +	 * @vgp: setting for VGP, the positive gamma divider voltages
> +	 * VGMP the high voltage and VGSP the low voltage.
> +	 * The first byte contains bit 8 of VGMP and VGSP in bits 4 and 0
> +	 * The second byte contains bit 0..7 of VGMP
> +	 * The third byte contains bit 0..7 of VGSP
> +	 * VGMP 0x00 = 3.0V .. 0x108 = 6.3V in steps of 12.5mV
> +	 * VGSP 0x00 = 0V .. 0x111 = 3.7V in steps of 12.5mV
> +	 */
> +	u8 vgp[NT35510_P1_VGP_LEN];
> +	/**
> +	 * @vgn: setting for VGN, the negative gamma divider voltages,
> +	 * same layout of bytes as @vgp.
> +	 */
> +	u8 vgn[NT35510_P1_VGN_LEN];
> +	/**
> +	 * @sdeqctr: Source driver control settings, first byte is
> +	 * 0 for mode 1 and 1 for mode 2. Mode 1 uses two steps and
> +	 * mode 2 uses three steps meaning EQS3 is not used in mode
> +	 * 1. Mode 2 is default. The last three parameters are EQS1, EQS2
> +	 * and EQS3, setting the rise time for each equalizer step:
> +	 * 0x00 = 0.0 us to 0x0f = 7.5 us in steps of 0.5us. The default
> +	 * is 0x07 = 3.5 us.
> +	 */
> +	u8 sdeqctr[NT35510_P0_SDEQCTR_LEN];
> +	/**
> +	 * @sdvpctr: power/voltage behaviour during vertical porch time
> +	 */
> +	u8 sdvpctr;
> +	/**
> +	 * @t1: the number of pixel clocks on one scanline, range
> +	 * 0x100 (258 ticks) .. 0x3FF (1024 ticks) so the value + 1
> +	 * clock ticks.
> +	 */
> +	u16 t1;
> +	/**
> +	 * @vbp: vertical back porch toward the PANEL note: not toward
> +	 * the DSI host; these are separate interfaces, in from DSI host
> +	 * and out to the panel.
> +	 */
> +	u8 vbp;
> +	/**
> +	 * @vfp: vertical front porch toward the PANEL.
> +	 */
> +	u8 vfp;
> +	/**
> +	 * @psel: pixel clock divisor: 0 = 1, 1 = 2, 2 = 4, 3 = 8.
> +	 */
> +	u8 psel;
> +	/**
> +	 * @dpmctr12: Display timing control 12
> +	 * Byte 1 bit 4 selects LVGL voltage level: 0 = VGLX, 1 = VGL_REG
> +	 * Byte 1 bit 1 selects gate signal mode: 0 = non-overlap, 1 = overlap
> +	 * Byte 1 bit 0 selects output signal control R/L swap, 0 = normal
> +	 * 1 = swap all O->E, L->R
> +	 * Byte 2 is CLW delay clock for CK O/E and CKB O/E signals:
> +	 * 0x00 = 0us .. 0xFF = 12.75us in 0.05us steps
> +	 * Byte 3 is FTI_H0 delay time for STP O/E signals:
> +	 * 0x00 = 0us .. 0xFF = 12.75us in 0.05us steps
> +	 */
> +	u8 dpmctr12[NT35510_P0_DPMCTR12_LEN];
> +	/**
> +	 * @gamma_corr_pos_r: Red gamma correction parameters, positive
> +	 */
> +	u8 gamma_corr_pos_r[NT35510_P1_GAMMA_LEN];
> +	/**
> +	 * @gamma_corr_pos_g: Green gamma correction parameters, positive
> +	 */
> +	u8 gamma_corr_pos_g[NT35510_P1_GAMMA_LEN];
> +	/**
> +	 * @gamma_corr_pos_b: Blue gamma correction parameters, positive
> +	 */
> +	u8 gamma_corr_pos_b[NT35510_P1_GAMMA_LEN];
> +	/**
> +	 * @gamma_corr_neg_r: Red gamma correction parameters, negative
> +	 */
> +	u8 gamma_corr_neg_r[NT35510_P1_GAMMA_LEN];
> +	/**
> +	 * @gamma_corr_neg_g: Green gamma correction parameters, negative
> +	 */
> +	u8 gamma_corr_neg_g[NT35510_P1_GAMMA_LEN];
> +	/**
> +	 * @gamma_corr_neg_b: Blue gamma correction parameters, negative
> +	 */
> +	u8 gamma_corr_neg_b[NT35510_P1_GAMMA_LEN];
> +};
> +
> +/**
> + * struct nt35510 - state container for the NT35510 panel
> + */
> +struct nt35510 {
> +	/**
> +	 * @dev: the container device
> +	 */
> +	struct device *dev;
> +	/**
> +	 * @conf: the specific panel configuration, as the NT35510
> +	 * can be combined with many physical panels, they can have
> +	 * different physical dimensions and gamma correction etc,
> +	 * so this is stored in the config.
> +	 */
> +	const struct nt35510_config *conf;
> +	/**
> +	 * @panel: the DRM panel object for the instance
> +	 */
> +	struct drm_panel panel;
> +	/**
> +	 * @supplies: regulators supplying the panel
> +	 */
> +	struct regulator_bulk_data supplies[2];
> +	/**
> +	 * @reset_gpio: the reset line
> +	 */
> +	struct gpio_desc *reset_gpio;
> +};
> +
> +/* Manufacturer command has strictly this byte sequence */
> +static const u8 nt35510_mauc_select_page_0[] = { 0x55, 0xAA, 0x52, 0x08, 0x00 };
> +static const u8 nt35510_mauc_select_page_1[] = { 0x55, 0xAA, 0x52, 0x08, 0x01 };
> +static const u8 nt35510_vgh_on[] = { 0x01 };
> +
> +static inline struct nt35510 *panel_to_nt35510(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct nt35510, panel);
> +}
> +
> +#define NT35510_ROTATE_0_SETTING	0x02
> +#define NT35510_ROTATE_180_SETTING	0x00
> +
> +static int nt35510_send_long(struct nt35510 *nt, struct mipi_dsi_device *dsi,
> +			     u8 cmd, u8 cmdlen, const u8 *seq)
> +{
> +	const u8 *seqp = seq;
> +	int cmdwritten = 0;
> +	int chunk = cmdlen;
> +	int ret;
> +
> +	if (chunk > 15)
> +		chunk = 15;
> +	ret = mipi_dsi_dcs_write(dsi, cmd, seqp, chunk);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(nt->dev,
> +			      "error sending DCS command seq cmd %02x\n",
> +			      cmd);
> +		return ret;
> +	}
> +	cmdwritten += chunk;
> +	seqp += chunk;
> +
> +	while (cmdwritten < cmdlen) {
> +		chunk = cmdlen - cmdwritten;
> +		if (chunk > 15)
> +			chunk = 15;
> +		ret = mipi_dsi_generic_write(dsi, seqp, chunk);
> +		if (ret < 0) {
> +			DRM_DEV_ERROR(nt->dev,
> +				      "error sending generic write seq %02x\n",
> +				      cmd);
> +			return ret;
> +		}
> +		cmdwritten += chunk;
> +		seqp += chunk;
> +	}
> +	DRM_DEV_DEBUG(nt->dev, "sent command %02x %02x bytes\n",
> +		      cmd, cmdlen);
> +	return 0;
> +}
> +
> +static int nt35510_read_id(struct nt35510 *nt)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
> +	u8 id1, id2, id3;
> +	int ret;
> +
> +	ret = mipi_dsi_dcs_read(dsi, MCS_CMD_READ_ID1, &id1, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(nt->dev, "could not read MTP ID1\n");
> +		return ret;
> +	}
> +	ret = mipi_dsi_dcs_read(dsi, MCS_CMD_READ_ID2, &id2, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(nt->dev, "could not read MTP ID2\n");
> +		return ret;
> +	}
> +	ret = mipi_dsi_dcs_read(dsi, MCS_CMD_READ_ID3, &id3, 1);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(nt->dev, "could not read MTP ID3\n");
> +		return ret;
> +	}
> +
> +	/*
> +	 * Multi-Time Programmable (?) memory contains manufacturer
> +	 * ID (e.g. Hydis 0x55), driver ID (e.g. NT35510 0xc0) and
> +	 * version.
> +	 */
> +	DRM_DEV_INFO(nt->dev,
> +		     "MTP ID manufacturer: %02x version: %02x driver: %02x\n",
> +		     id1, id2, id3);
> +
> +	return 0;
> +}
> +
> +/**
> + * nt35510_setup_power() - set up power config in page 1
> + * @nt: the display instance to set up
> + */
> +static int nt35510_setup_power(struct nt35510 *nt)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
> +	int ret;
> +
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETAVDD,
> +				NT35510_P1_AVDD_LEN,
> +				nt->conf->avdd);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT1CTR,
> +				NT35510_P1_BT1CTR_LEN,
> +				nt->conf->bt1ctr);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETAVEE,
> +				NT35510_P1_AVEE_LEN,
> +				nt->conf->avee);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT2CTR,
> +				NT35510_P1_BT2CTR_LEN,
> +				nt->conf->bt2ctr);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGH,
> +				NT35510_P1_VGH_LEN,
> +				nt->conf->vgh);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT4CTR,
> +				NT35510_P1_BT4CTR_LEN,
> +				nt->conf->bt4ctr);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_VGHCTR,
> +				ARRAY_SIZE(nt35510_vgh_on),
> +				nt35510_vgh_on);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGL,
> +				NT35510_P1_VGL_LEN,
> +				nt->conf->vgl);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT5CTR,
> +				NT35510_P1_BT5CTR_LEN,
> +				nt->conf->bt5ctr);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGP,
> +				NT35510_P1_VGP_LEN,
> +				nt->conf->vgp);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGN,
> +				NT35510_P1_VGN_LEN,
> +				nt->conf->vgn);
> +	if (ret)
> +		return ret;
> +
> +	/* Typically 10 ms */
> +	usleep_range(10000, 20000);
> +
> +	return 0;
> +}
> +
> +/**
> + * nt35510_setup_display() - set up display config in page 0
> + * @nt: the display instance to set up
> + */
> +static int nt35510_setup_display(struct nt35510 *nt)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
> +	const struct nt35510_config *conf = nt->conf;
> +	u8 dopctr[NT35510_P0_DOPCTR_LEN];
> +	u8 gseqctr[NT35510_P0_GSEQCTR_LEN];
> +	u8 dpfrctr[NT35510_P0_DPFRCTR1_LEN];
> +	/* FIXME: set up any rotation (assume none for now) */
> +	u8 addr_mode = NT35510_ROTATE_0_SETTING;
> +	u8 val;
> +	int ret;
> +
> +	/* Enable TE, EoTP and RGB pixel format */
> +	dopctr[0] = NT35510_DOPCTR_0_DSITE | NT35510_DOPCTR_0_EOTP |
> +		NT35510_DOPCTR_0_N565;
> +	dopctr[1] = NT35510_DOPCTR_1_CTB;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P0_DOPCTR,
> +				NT35510_P0_DOPCTR_LEN,
> +				dopctr);
> +	if (ret)
> +		return ret;
> +
> +	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_ADDRESS_MODE, &addr_mode,
> +				 sizeof(addr_mode));
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * Source data hold time, default 0x05 = 2.5us
> +	 * 0x00..0x3F = 0 .. 31.5us in steps of 0.5us
> +	 * 0x0A = 5us
> +	 */
> +	val = 0x0A;
> +	ret = mipi_dsi_dcs_write(dsi, NT35510_P0_SDHDTCTR, &val,
> +				 sizeof(val));
> +	if (ret < 0)
> +		return ret;
> +
> +	/* EQ control for gate signals, 0x00 = 0 us */
> +	gseqctr[0] = 0x00;
> +	gseqctr[1] = 0x00;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P0_GSEQCTR,
> +				NT35510_P0_GSEQCTR_LEN,
> +				gseqctr);
> +	if (ret)
> +		return ret;
> +
> +	ret = nt35510_send_long(nt, dsi, NT35510_P0_SDEQCTR,
> +				NT35510_P0_SDEQCTR_LEN,
> +				conf->sdeqctr);
> +	if (ret)
> +		return ret;
> +
> +	ret = mipi_dsi_dcs_write(dsi, NT35510_P0_SDVPCTR,
> +				 &conf->sdvpctr, 1);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * Display timing control for active and idle off mode:
> +	 * the first byte contains
> +	 * the two high bits of T1A and second byte the low 8 bits, and
> +	 * the valid range is 0x100 (257) to 0x3ff (1023) representing
> +	 * 258..1024 (+1) pixel clock ticks for one scanline. At 20MHz pixel
> +	 * clock this covers the range of 12.90us .. 51.20us in steps of
> +	 * 0.05us, the default is 0x184 (388) representing 389 ticks.
> +	 * The third byte is VBPDA, vertical back porch display active
> +	 * and the fourth VFPDA, vertical front porch display active,
> +	 * both given in number of scanlines in the range 0x02..0xff
> +	 * for 2..255 scanlines. The fifth byte is 2 bits selecting
> +	 * PSEL for active and idle off mode, how much the 20MHz clock
> +	 * is divided by 0..3.  This needs to be adjusted to get the right
> +	 * frame rate.
> +	 */
> +	dpfrctr[0] = (conf->t1 >> 8) & 0xFF;
> +	dpfrctr[1] = conf->t1 & 0xFF;
> +	/* Vertical back porch */
> +	dpfrctr[2] = conf->vbp;
> +	/* Vertical front porch */
> +	dpfrctr[3] = conf->vfp;
> +	dpfrctr[4] = conf->psel;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPFRCTR1,
> +				NT35510_P0_DPFRCTR1_LEN,
> +				dpfrctr);
> +	if (ret)
> +		return ret;
> +	/* For idle and partial idle off mode we decrease front porch by one */
> +	dpfrctr[3]--;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPFRCTR2,
> +				NT35510_P0_DPFRCTR2_LEN,
> +				dpfrctr);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPFRCTR3,
> +				NT35510_P0_DPFRCTR3_LEN,
> +				dpfrctr);
> +	if (ret)
> +		return ret;
> +
> +	/* Enable TE on vblank */
> +	ret = mipi_dsi_dcs_set_tear_on(dsi, MIPI_DSI_DCS_TEAR_MODE_VBLANK);
> +	if (ret)
> +		return ret;
> +
> +	/* Turn on the pads? */
> +	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPMCTR12,
> +				NT35510_P0_DPMCTR12_LEN,
> +				conf->dpmctr12);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int nt35510_set_brightness(struct backlight_device *bl)
> +{
> +	struct nt35510 *nt = bl_get_data(bl);
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
> +	u8 brightness = bl->props.brightness;
> +	int ret;
> +
> +	DRM_DEV_DEBUG(nt->dev, "set brightness %d\n", brightness);
> +	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
> +				 &brightness,
> +				 sizeof(brightness));
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static const struct backlight_ops nt35510_bl_ops = {
> +	.update_status = nt35510_set_brightness,
> +};
> +
> +/*
> + * This power-on sequence
> + */
> +static int nt35510_power_on(struct nt35510 *nt)
> +{
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
> +	int ret;
> +
> +	ret = regulator_bulk_enable(ARRAY_SIZE(nt->supplies), nt->supplies);
> +	if (ret < 0) {
> +		dev_err(nt->dev, "unable to enable regulators\n");
> +		return ret;
> +	}
> +
> +	/* Toggle RESET in accordance with datasheet page 370 */
> +	if (nt->reset_gpio) {
> +		gpiod_set_value(nt->reset_gpio, 1);
> +		/* Active min 10 us according to datasheet, let's say 20 */
> +		usleep_range(20, 1000);
> +		gpiod_set_value(nt->reset_gpio, 0);
> +		/*
> +		 * 5 ms during sleep mode, 120 ms during sleep out mode
> +		 * according to datasheet, let's use 120-140 ms.
> +		 */
> +		usleep_range(120000, 140000);
> +	}
> +
> +	ret = nt35510_read_id(nt);
> +	if (ret)
> +		return ret;
> +
> +	/* Set up stuff in  manufacturer control, page 1 */
> +	ret = nt35510_send_long(nt, dsi, MCS_CMD_MAUCCTR,
> +				ARRAY_SIZE(nt35510_mauc_select_page_1),
> +				nt35510_mauc_select_page_1);
> +	if (ret)
> +		return ret;
> +
> +	ret = nt35510_setup_power(nt);
> +	if (ret)
> +		return ret;
> +
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_RED_POS,
> +				NT35510_P1_GAMMA_LEN,
> +				nt->conf->gamma_corr_pos_r);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_GREEN_POS,
> +				NT35510_P1_GAMMA_LEN,
> +				nt->conf->gamma_corr_pos_g);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_BLUE_POS,
> +				NT35510_P1_GAMMA_LEN,
> +				nt->conf->gamma_corr_pos_b);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_RED_NEG,
> +				NT35510_P1_GAMMA_LEN,
> +				nt->conf->gamma_corr_neg_r);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_GREEN_NEG,
> +				NT35510_P1_GAMMA_LEN,
> +				nt->conf->gamma_corr_neg_g);
> +	if (ret)
> +		return ret;
> +	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_BLUE_NEG,
> +				NT35510_P1_GAMMA_LEN,
> +				nt->conf->gamma_corr_neg_b);
> +	if (ret)
> +		return ret;
> +
> +	/* Set up stuff in  manufacturer control, page 0 */
> +	ret = nt35510_send_long(nt, dsi, MCS_CMD_MAUCCTR,
> +				ARRAY_SIZE(nt35510_mauc_select_page_0),
> +				nt35510_mauc_select_page_0);
> +	if (ret)
> +		return ret;
> +
> +	ret = nt35510_setup_display(nt);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int nt35510_power_off(struct nt35510 *nt)
> +{
> +	int ret;
> +
> +	ret = regulator_bulk_disable(ARRAY_SIZE(nt->supplies), nt->supplies);
> +	if (ret)
> +		return ret;
> +
> +	if (nt->reset_gpio)
> +		gpiod_set_value(nt->reset_gpio, 1);
> +
> +	return 0;
> +}
> +
> +static int nt35510_unprepare(struct drm_panel *panel)
> +{
> +	struct nt35510 *nt = panel_to_nt35510(panel);
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
> +	int ret;
> +
> +	ret = mipi_dsi_dcs_set_display_off(dsi);
> +	if (ret) {
> +		DRM_DEV_ERROR(nt->dev, "failed to turn display off (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	usleep_range(10000, 20000);
> +
> +	/* Enter sleep mode */
> +	ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
> +	if (ret) {
> +		DRM_DEV_ERROR(nt->dev, "failed to enter sleep mode (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +
> +	/* Wait 4 frames, how much is that 5ms in the vendor driver */
> +	usleep_range(5000, 10000);
> +
> +	ret = nt35510_power_off(nt);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int nt35510_prepare(struct drm_panel *panel)
> +{
> +	struct nt35510 *nt = panel_to_nt35510(panel);
> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
> +	int ret;
> +
> +	ret = nt35510_power_on(nt);
> +	if (ret)
> +		return ret;
> +
> +	/* Exit sleep mode */
> +	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
> +	if (ret) {
> +		DRM_DEV_ERROR(nt->dev, "failed to exit sleep mode (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	/* Up to 120 ms */
> +	usleep_range(120000, 150000);
> +
> +	ret = mipi_dsi_dcs_set_display_on(dsi);
> +	if (ret) {
> +		DRM_DEV_ERROR(nt->dev, "failed to turn display on (%d)\n",
> +			      ret);
> +		return ret;
> +	}
> +	/* Some 10 ms */
> +	usleep_range(10000, 20000);
> +
> +	return 0;
> +}
> +
> +static int nt35510_get_modes(struct drm_panel *panel,
> +			     struct drm_connector *connector)
> +{
> +	struct nt35510 *nt = panel_to_nt35510(panel);
> +	struct drm_display_mode *mode;
> +	struct drm_display_info *info;
> +
> +	info = &connector->display_info;
> +	info->width_mm = nt->conf->width_mm;
> +	info->height_mm = nt->conf->height_mm;
> +	mode = drm_mode_duplicate(connector->dev, &nt->conf->mode);
> +	if (!mode) {
> +		DRM_ERROR("bad mode or failed to add mode\n");
> +		return -EINVAL;
> +	}
> +	drm_mode_set_name(mode);
> +	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
> +
> +	mode->width_mm = nt->conf->width_mm;
> +	mode->height_mm = nt->conf->height_mm;
> +	drm_mode_probed_add(connector, mode);
> +
> +	return 1; /* Number of modes */
> +}
> +
> +static const struct drm_panel_funcs nt35510_drm_funcs = {
> +	.unprepare = nt35510_unprepare,
> +	.prepare = nt35510_prepare,
> +	.get_modes = nt35510_get_modes,
> +};
> +
> +static int nt35510_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct nt35510 *nt;
> +	int ret;
> +
> +	nt = devm_kzalloc(dev, sizeof(struct nt35510), GFP_KERNEL);
> +	if (!nt)
> +		return -ENOMEM;
> +	mipi_dsi_set_drvdata(dsi, nt);
> +	nt->dev = dev;
> +
> +	dsi->lanes = 2;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	/*
> +	 * Datasheet suggests max HS rate for NT35510 is 250 MHz
> +	 * (period time 4ns, see figure 7.6.4 page 365) and max LP rate is
> +	 * 20 MHz (period time 50ns, see figure 7.6.6. page 366).
> +	 * However these frequencies appear in source code for the Hydis
> +	 * HVA40WV1 panel and setting up the LP frequency makes the panel
> +	 * not work.
> +	 *
> +	 * TODO: if other panels prove to be closer to the datasheet,
> +	 * maybe make this a per-panel config in struct nt35510_config?
> +	 */
> +	dsi->hs_rate = 349440000;
> +	dsi->lp_rate = 9600000;
> +	dsi->mode_flags = MIPI_DSI_CLOCK_NON_CONTINUOUS |
> +		MIPI_DSI_MODE_EOT_PACKET;
> +
> +	/*
> +	 * Every new incarnation of this display must have a unique
> +	 * data entry for the system in this driver.
> +	 */
> +	nt->conf = of_device_get_match_data(dev);
> +	if (!nt->conf) {
> +		dev_err(dev, "missing device configuration\n");
> +		return -ENODEV;
> +	}
> +
> +	nt->supplies[0].supply = "vdd"; /* 2.3-4.8 V */
> +	nt->supplies[1].supply = "vddi"; /* 1.65-3.3V */
> +	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(nt->supplies),
> +				      nt->supplies);
> +	if (ret < 0)
> +		return ret;
> +	ret = regulator_set_voltage(nt->supplies[0].consumer,
> +				    2300000, 4800000);
> +	if (ret)
> +		return ret;
> +	ret = regulator_set_voltage(nt->supplies[1].consumer,
> +				    1650000, 3300000);
> +	if (ret)
> +		return ret;
> +
> +	nt->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_ASIS);
> +	if (IS_ERR(nt->reset_gpio)) {
> +		dev_err(dev, "error getting RESET GPIO\n");
> +		return PTR_ERR(nt->reset_gpio);
> +	}
> +
> +	drm_panel_init(&nt->panel, dev, &nt35510_drm_funcs,
> +		       DRM_MODE_CONNECTOR_DSI);
> +
> +	/*
> +	 * First, try to locate an external backlight (such as on GPIO)
> +	 * if this fails, assume we will want to use the internal backlight
> +	 * control.
> +	 */
> +	ret = drm_panel_of_backlight(&nt->panel);
> +	if (ret) {
> +		dev_err(dev, "error getting external backlight %d\n", ret);
> +		return ret;
> +	}
> +	if (!nt->panel.backlight) {
> +		struct backlight_device *bl;
> +
> +		bl = devm_backlight_device_register(dev, "nt35510", dev, nt,
> +						    &nt35510_bl_ops, NULL);
> +		if (IS_ERR(bl)) {
> +			DRM_DEV_ERROR(dev, "failed to register backlight device\n");
> +			return PTR_ERR(bl);
> +		}
> +		bl->props.max_brightness = 255;
> +		bl->props.brightness = 255;
> +		bl->props.power = FB_BLANK_POWERDOWN;
> +		nt->panel.backlight = bl;
> +	}
> +
> +	ret = drm_panel_add(&nt->panel);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret < 0)
> +		drm_panel_remove(&nt->panel);
> +
> +	return 0;
> +}
> +
> +static int nt35510_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct nt35510 *nt = mipi_dsi_get_drvdata(dsi);
> +	int ret;
> +
> +	mipi_dsi_detach(dsi);
> +	/* Power off */
> +	ret = nt35510_power_off(nt);
> +	drm_panel_remove(&nt->panel);
> +
> +	return ret;
> +}
> +
> +/*
> + * These gamma correction values are 10bit tuples, so only bits 0 and 1 is
> + * ever used in the first byte. They form a positive and negative gamma
> + * correction curve for each color, values must be strictly higher for each
> + * step on the curve. As can be seen these default curves goes from 0x0001
> + * to 0x03FE.
> + */
> +#define NT35510_GAMMA_POS_DEFAULT 0x00, 0x01, 0x00, 0x43, 0x00, \
> +		0x6B, 0x00, 0x87, 0x00, 0xA3, 0x00, 0xCE, 0x00, 0xF1, 0x01, \
> +		0x27, 0x01, 0x53, 0x01, 0x98, 0x01, 0xCE, 0x02, 0x22, 0x02, \
> +		0x83, 0x02, 0x78, 0x02, 0x9E, 0x02, 0xDD, 0x03, 0x00, 0x03, \
> +		0x2E, 0x03, 0x54, 0x03, 0x7F, 0x03, 0x95, 0x03, 0xB3, 0x03, \
> +		0xC2, 0x03, 0xE1, 0x03, 0xF1, 0x03, 0xFE
> +
> +#define NT35510_GAMMA_NEG_DEFAULT 0x00, 0x01, 0x00, 0x43, 0x00, \
> +		0x6B, 0x00, 0x87, 0x00, 0xA3, 0x00, 0xCE, 0x00, 0xF1, 0x01, \
> +		0x27, 0x01, 0x53, 0x01, 0x98, 0x01, 0xCE, 0x02, 0x22, 0x02, \
> +		0x43, 0x02, 0x50, 0x02, 0x9E, 0x02, 0xDD, 0x03, 0x00, 0x03, \
> +		0x2E, 0x03, 0x54, 0x03, 0x7F, 0x03, 0x95, 0x03, 0xB3, 0x03, \
> +		0xC2, 0x03, 0xE1, 0x03, 0xF1, 0x03, 0xFE
> +
> +/*
> + * The Hydis HVA40WV1 panel
> + */
> +static const struct nt35510_config nt35510_hydis_hva40wv1 = {
> +	.width_mm = 52,
> +	.height_mm = 86,
> +	/**
> +	 * As the Hydis panel is used in command mode, the porches etc
> +	 * are settings programmed internally into the NT35510 controller
> +	 * and generated toward the physical display. As the panel is not
> +	 * used in video mode, these are not really exposed to the DSI
> +	 * host.
> +	 *
> +	 * Display frame rate control:
> +	 * Frame rate = (20 MHz / 1) / (389 * (7 + 50 + 800)) ~= 60 Hz
> +	 */
> +	.mode = {
> +		/* The internal pixel clock of the NT35510 is 20 MHz */
> +		.clock = 20000000,
> +		.hdisplay = 480,
> +		.hsync_start = 480 + 2, /* HFP = 2 */
> +		.hsync_end = 480 + 2 + 0, /* HSync = 0 */
> +		.htotal = 480 + 2 + 0 + 5, /* HFP = 5 */
> +		.vdisplay = 800,
> +		.vsync_start = 800 + 2, /* VFP = 2 */
> +		.vsync_end = 800 + 2 + 0, /* VSync = 0 */
> +		.vtotal = 800 + 2 + 0 + 5, /* VBP = 5 */
> +		.vrefresh = 60, /* Calculated */
> +		.flags = 0,
> +	},
> +	/* 0x09: AVDD = 5.6V */
> +	.avdd = { 0x09, 0x09, 0x09 },
> +	/* 0x34: PCK = Hsync/2, BTP = 2 x VDDB */
> +	.bt1ctr = { 0x34, 0x34, 0x34 },
> +	/* 0x09: AVEE = -5.6V */
> +	.avee = { 0x09, 0x09, 0x09 },
> +	/* 0x24: NCK = Hsync/2, BTN =  -2 x VDDB */
> +	.bt2ctr = { 0x24, 0x24, 0x24 },
> +	/* 0x05 = 12V */
> +	.vgh = { 0x05, 0x05, 0x05 },
> +	/* 0x24: NCKA = Hsync/2, VGH = 2 x AVDD - AVEE */
> +	.bt4ctr = { 0x24, 0x24, 0x24 },
> +	/* 0x0B = -13V */
> +	.vgl = { 0x0B, 0x0B, 0x0B },
> +	/* 0x24: LCKA = Hsync, VGL = AVDD + VCL - AVDD */
> +	.bt5ctr = { 0x24, 0x24, 0x24 },
> +	/* VGMP: 0x0A3 = 5.0375V, VGSP = 0V */
> +	.vgp = { 0x00, 0xA3, 0x00 },
> +	/* VGMP: 0x0A3 = 5.0375V, VGSP = 0V */
> +	.vgn = { 0x00, 0xA3, 0x00 },
> +	/* SDEQCTR: source driver EQ mode 2, 2.5 us rise time on each step */
> +	.sdeqctr = { 0x01, 0x05, 0x05, 0x05 },
> +	/* SDVPCTR: Normal operation off color during v porch */
> +	.sdvpctr = 0x01,
> +	/* T1: number of pixel clocks on one scanline: 0x184 = 389 clocks */
> +	.t1 = 0x0184,
> +	/* VBP: vertical back porch toward the panel */
> +	.vbp = 7,
> +	/* VFP: vertical front porch toward the panel */
> +	.vfp = 50,
> +	/* PSEL: divide pixel clock 20MHz with 1 (no clock downscaling) */
> +	.psel = 0,
> +	/* DPTMCTR12: 0x03: LVGL = VGLX, overlap mode, swap R->L O->E */
> +	.dpmctr12 = { 0x03, 0x00, 0x00, },
> +	/* Default gamma correction values */
> +	.gamma_corr_pos_r = { NT35510_GAMMA_POS_DEFAULT },
> +	.gamma_corr_pos_g = { NT35510_GAMMA_POS_DEFAULT },
> +	.gamma_corr_pos_b = { NT35510_GAMMA_POS_DEFAULT },
> +	.gamma_corr_neg_r = { NT35510_GAMMA_NEG_DEFAULT },
> +	.gamma_corr_neg_g = { NT35510_GAMMA_NEG_DEFAULT },
> +	.gamma_corr_neg_b = { NT35510_GAMMA_NEG_DEFAULT },
> +};
> +
> +static const struct of_device_id nt35510_of_match[] = {
> +	{
> +		.compatible = "hydis,hva40wv1",
> +		.data = &nt35510_hydis_hva40wv1,
> +	},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, nt35510_of_match);
> +
> +static struct mipi_dsi_driver nt35510_driver = {
> +	.probe = nt35510_probe,
> +	.remove = nt35510_remove,
> +	.driver = {
> +		.name = "panel-novatek-nt35510",
> +		.of_match_table = nt35510_of_match,
> +	},
> +};
> +module_mipi_dsi_driver(nt35510_driver);
> +
> +MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
> +MODULE_DESCRIPTION("NT35510-based panel driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.21.1
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Re: [PATCH 1/3 v2] dt-bindings: Add vendor prefix for Hydis technologies

[Rob Herring]

On Sun, 23 Feb 2020 13:18:39 +0100, Linus Walleij wrote:
> This vendor has produced a number of display panels,
> including HVA40WV1.
> 
> Cc: devicetree@vger.kernel.org
> Cc: Stephan Gerhold <stephan@gerhold.net>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ChangeLog v1->v2:
> - New patch adding this vendor.
> ---
>  Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
>  1 file changed, 2 insertions(+)
> 

Acked-by: Rob Herring <robh@kernel.org>
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Re: [PATCH 1/3 v2] dt-bindings: Add vendor prefix for Hydis technologies

[Sam Ravnborg]

On Sun, Feb 23, 2020 at 01:18:39PM +0100, Linus Walleij wrote:
> This vendor has produced a number of display panels,
> including HVA40WV1.
> 
> Cc: devicetree@vger.kernel.org
> Cc: Stephan Gerhold <stephan@gerhold.net>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Applied to drm-misc-next with Rob's ack

> ---
> ChangeLog v1->v2:
> - New patch adding this vendor.
> ---
>  Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
> index 9e67944bec9c..95ef233dbb52 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
> @@ -421,6 +421,8 @@ patternProperties:
>      description: Shenzhen Hugsun Technology Co. Ltd.
>    "^hwacom,.*":
>      description: HwaCom Systems Inc.
> +  "^hydis,.*":
> +    description: Hydis Technologies
>    "^hyundai,.*":
>      description: Hyundai Technology
>    "^i2se,.*":
> -- 
> 2.21.1
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