Message-Id: <20190124182844.28961-2-jagan@amarulasolutions.com>
Date:   Thu, 24 Jan 2019 23:58:44 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Sam Ravnborg <sam@...nborg.org>
Cc:     Michael Trimarchi <michael@...rulasolutions.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-amarula@...rulasolutions.com,
        Jagan Teki <jagan@...rulasolutions.com>
Subject: [PATCH v8 2/2] drm/panel: Add Sitronix ST7701 panel driver

ST7701 designed for small and medium sizes of TFT LCD display, is
capable of supporting up to 480RGBX864 in resolution. It provides
several system interfaces like MIPI/RGB/SPI.

Currently added support for Techstar TS8550B which is ST7701 based
480x854, 2-lane MIPI DSI LCD panel.

Driver now registering mipi_dsi device, but indeed it can extendable
for RGB if any requirement trigger in future.

Signed-off-by: Jagan Teki <jagan@...rulasolutions.com>
---
Changes for v8:
- use DRM_DEV_ERROR instead of dev_err
- use devm_of_find_backlight() instead of of_parse_phandle()
- remove unneeded 'num_supplies' from struct st7701
- add proper comments about panel sepecific sleep mode delay as
  per st7701 datasheet
- update msleep delay values in .prepare as per datasheet and as per
  discussion in v7, thanks to 'Sam Ravnborg'  
- update msleep delay values in .unprepare as per datasheet and as per
  discussion in v7, thanks to 'Sam Ravnborg' 
- add proper comments on msleep delay values as per st7701 datasheet 
- use MIPI_DCS_ENTER_SLEEP_MODE in .unprepare
- drop unneeded gpio set in .prepare and .unprepare as per panel-simple
- remove unneeded include files
- rebase on master
Changes for v7:
- rebase on master
Changes for v6:
- use sleep delay value as per datasheet
- add panel_sleep_delay variable for panel specific delay
- use command sequnce display on and off instead panel
  functions
- add proper comments on the delays
- remove delays from command switch
- move mode type on struct display mode
- drop refresh rate value, let drm compute  
Changes for v5:
- found the chip from vendor, so added new panel driver
- here is v4: https://patchwork.kernel.org/patch/10680335/

 MAINTAINERS                                   |   6 +
 drivers/gpu/drm/panel/Kconfig                 |  10 +
 drivers/gpu/drm/panel/Makefile                |   1 +
 drivers/gpu/drm/panel/panel-sitronix-st7701.c | 429 ++++++++++++++++++
 4 files changed, 446 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-sitronix-st7701.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 5c8591eb5840..875bba40157b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4937,6 +4937,12 @@ S:	Orphan / Obsolete
 F:	drivers/gpu/drm/sis/
 F:	include/uapi/drm/sis_drm.h
 
+DRM DRIVER FOR SITRONIX ST7701 PANELS
+M:	Jagan Teki <jagan@...rulasolutions.com>
+S:	Maintained
+F:	drivers/gpu/drm/panel/panel-sitronix-st7701.c
+F:	Documentation/devicetree/bindings/display/panel/sitronix,st7701.txt
+
 DRM DRIVER FOR SITRONIX ST7586 PANELS
 M:	David Lechner <david@...hnology.com>
 S:	Maintained
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 5304db7b7b55..a65b3a065598 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -214,6 +214,16 @@ config DRM_PANEL_SHARP_LS043T1LE01
 	  Say Y here if you want to enable support for Sharp LS043T1LE01 qHD
 	  (540x960) DSI panel as found on the Qualcomm APQ8074 Dragonboard
 
+config DRM_PANEL_SITRONIX_ST7701
+	tristate "Sitronix ST7701 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 Sitronix
+	  ST7701 controller for 480X864 LCD panels with MIPI/RGB/SPI
+	  system interfaces.
+
 config DRM_PANEL_SITRONIX_ST7789V
 	tristate "Sitronix ST7789V panel"
 	depends on OF && SPI
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index c88dacf9d439..0ec4c41915dd 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E8AA0) += panel-samsung-s6e8aa0.o
 obj-$(CONFIG_DRM_PANEL_SEIKO_43WVF1G) += panel-seiko-43wvf1g.o
 obj-$(CONFIG_DRM_PANEL_SHARP_LQ101R1SX01) += panel-sharp-lq101r1sx01.o
 obj-$(CONFIG_DRM_PANEL_SHARP_LS043T1LE01) += panel-sharp-ls043t1le01.o
+obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7701) += panel-sitronix-st7701.o
 obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7789V) += panel-sitronix-st7789v.o
 obj-$(CONFIG_DRM_PANEL_TPO_TPG110) += panel-tpo-tpg110.o
 obj-$(CONFIG_DRM_PANEL_TRULY_NT35597_WQXGA) += panel-truly-nt35597.o
diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7701.c b/drivers/gpu/drm/panel/panel-sitronix-st7701.c
new file mode 100644
index 000000000000..499dd8a34a6d
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-sitronix-st7701.c
@@ -0,0 +1,429 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019, Amarula Solutions.
+ * Author: Jagan Teki <jagan@...rulasolutions.com>
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+
+#include <linux/gpio/consumer.h>
+#include <linux/regulator/consumer.h>
+
+#include <drm/drmP.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_panel.h>
+
+#include <video/mipi_display.h>
+
+/* Command2 BKx selection command */
+#define DSI_CMD2BKX_SEL			0xFF
+
+/* Command2, BK0 commands */
+#define DSI_CMD2_BK0_PVGAMCTRL		0xB0 /* Positive Voltage Gamma Control */
+#define DSI_CMD2_BK0_NVGAMCTRL		0xB1 /* Negative Voltage Gamma Control */
+#define DSI_CMD2_BK0_LNESET		0xC0 /* Display Line setting */
+#define DSI_CMD2_BK0_PORCTRL		0xC1 /* Porch control */
+#define DSI_CMD2_BK0_INVSEL		0xC2 /* Inversion selection, Frame Rate Control */
+
+/* Command2, BK1 commands */
+#define DSI_CMD2_BK1_VRHS		0xB0 /* Vop amplitude setting */
+#define DSI_CMD2_BK1_VCOM		0xB1 /* VCOM amplitude setting */
+#define DSI_CMD2_BK1_VGHSS		0xB2 /* VGH Voltage setting */
+#define DSI_CMD2_BK1_TESTCMD		0xB3 /* TEST Command Setting */
+#define DSI_CMD2_BK1_VGLS		0xB5 /* VGL Voltage setting */
+#define DSI_CMD2_BK1_PWCTLR1		0xB7 /* Power Control 1 */
+#define DSI_CMD2_BK1_PWCTLR2		0xB8 /* Power Control 2 */
+#define DSI_CMD2_BK1_SPD1		0xC1 /* Source pre_drive timing set1 */
+#define DSI_CMD2_BK1_SPD2		0xC2 /* Source EQ2 Setting */
+#define DSI_CMD2_BK1_MIPISET1		0xD0 /* MIPI Setting 1 */
+
+/**
+ * Command2 with BK function selection.
+ *
+ * BIT[4, 0]: [CN2, BKXSEL]
+ * 10 = CMD2BK0, Command2 BK0
+ * 11 = CMD2BK1, Command2 BK1
+ * 00 = Command2 disable
+ */
+#define DSI_CMD2BK1_SEL			0x11
+#define DSI_CMD2BK0_SEL			0x10
+#define DSI_CMD2BKX_SEL_NONE		0x00
+
+/* Command2, BK0 bytes */
+#define DSI_LINESET_LINE		0x69
+#define DSI_LINESET_LDE_EN		BIT(7)
+#define DSI_LINESET_LINEDELTA		GENMASK(1, 0)
+#define DSI_CMD2_BK0_LNESET_B1		DSI_LINESET_LINEDELTA
+#define DSI_CMD2_BK0_LNESET_B0		(DSI_LINESET_LDE_EN | DSI_LINESET_LINE)
+#define DSI_INVSEL_DEFAULT		GENMASK(5, 4)
+#define DSI_INVSEL_NLINV		GENMASK(2, 0)
+#define DSI_INVSEL_RTNI			GENMASK(2, 1)
+#define DSI_CMD2_BK0_INVSEL_B1		DSI_INVSEL_RTNI
+#define DSI_CMD2_BK0_INVSEL_B0		(DSI_INVSEL_DEFAULT | DSI_INVSEL_NLINV)
+#define DSI_CMD2_BK0_PORCTRL_B0(m)	((m)->vtotal - (m)->vsync_end)
+#define DSI_CMD2_BK0_PORCTRL_B1(m)	((m)->vsync_start - (m)->vdisplay)
+
+/* Command2, BK1 bytes */
+#define DSI_CMD2_BK1_VRHA_SET		0x45
+#define DSI_CMD2_BK1_VCOM_SET		0x13
+#define DSI_CMD2_BK1_VGHSS_SET		GENMASK(2, 0)
+#define DSI_CMD2_BK1_TESTCMD_VAL	BIT(7)
+#define DSI_VGLS_DEFAULT		BIT(6)
+#define DSI_VGLS_SEL			GENMASK(2, 0)
+#define DSI_CMD2_BK1_VGLS_SET		(DSI_VGLS_DEFAULT | DSI_VGLS_SEL)
+#define DSI_PWCTLR1_AP			BIT(7) /* Gamma OP bias, max */
+#define DSI_PWCTLR1_APIS		BIT(2) /* Source OP input bias, min */
+#define DSI_PWCTLR1_APOS		BIT(0) /* Source OP output bias, min */
+#define DSI_CMD2_BK1_PWCTLR1_SET	(DSI_PWCTLR1_AP | DSI_PWCTLR1_APIS | \
+					DSI_PWCTLR1_APOS)
+#define DSI_PWCTLR2_AVDD		BIT(5) /* AVDD 6.6v */
+#define DSI_PWCTLR2_AVCL		0x0    /* AVCL -4.4v */
+#define DSI_CMD2_BK1_PWCTLR2_SET	(DSI_PWCTLR2_AVDD | DSI_PWCTLR2_AVCL)
+#define DSI_SPD1_T2D			BIT(3)
+#define DSI_CMD2_BK1_SPD1_SET		(GENMASK(6, 4) | DSI_SPD1_T2D)
+#define DSI_CMD2_BK1_SPD2_SET		DSI_CMD2_BK1_SPD1_SET
+#define DSI_MIPISET1_EOT_EN		BIT(3)
+#define DSI_CMD2_BK1_MIPISET1_SET	(BIT(7) | DSI_MIPISET1_EOT_EN)
+
+struct st7701_panel_desc {
+	const struct drm_display_mode *mode;
+	unsigned int lanes;
+	unsigned long flags;
+	enum mipi_dsi_pixel_format format;
+	const char *const *supply_names;
+	unsigned int num_supplies;
+	unsigned int panel_sleep_delay;
+};
+
+struct st7701 {
+	struct drm_panel panel;
+	struct mipi_dsi_device *dsi;
+	const struct st7701_panel_desc *desc;
+
+	struct backlight_device *backlight;
+	struct regulator_bulk_data *supplies;
+	struct gpio_desc *reset;
+	unsigned int sleep_delay;
+};
+
+static inline struct st7701 *panel_to_st7701(struct drm_panel *panel)
+{
+	return container_of(panel, struct st7701, panel);
+}
+
+static inline int st7701_dsi_write(struct st7701 *st7701, const void *seq,
+				   size_t len)
+{
+	return mipi_dsi_dcs_write_buffer(st7701->dsi, seq, len);
+}
+
+#define ST7701_DSI(st7701, seq...)				\
+	{							\
+		const u8 d[] = { seq };				\
+		st7701_dsi_write(st7701, d, ARRAY_SIZE(d));	\
+	}
+
+static void st7701_init_sequence(struct st7701 *st7701)
+{
+	const struct drm_display_mode *mode = st7701->desc->mode;
+
+	ST7701_DSI(st7701, MIPI_DCS_SOFT_RESET, 0x00);
+
+	/* We need to wait 5ms before sending new commands */
+	msleep(5);
+
+	ST7701_DSI(st7701, MIPI_DCS_EXIT_SLEEP_MODE, 0x00);
+
+	msleep(st7701->sleep_delay);
+
+	/* Command2, BK0 */
+	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
+		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BK0_SEL);
+	ST7701_DSI(st7701, DSI_CMD2_BK0_PVGAMCTRL, 0x00, 0x0E, 0x15, 0x0F,
+		   0x11, 0x08, 0x08, 0x08, 0x08, 0x23, 0x04, 0x13, 0x12,
+		   0x2B, 0x34, 0x1F);
+	ST7701_DSI(st7701, DSI_CMD2_BK0_NVGAMCTRL, 0x00, 0x0E, 0x95, 0x0F,
+		   0x13, 0x07, 0x09, 0x08, 0x08, 0x22, 0x04, 0x10, 0x0E,
+		   0x2C, 0x34, 0x1F);
+	ST7701_DSI(st7701, DSI_CMD2_BK0_LNESET,
+		   DSI_CMD2_BK0_LNESET_B0, DSI_CMD2_BK0_LNESET_B1);
+	ST7701_DSI(st7701, DSI_CMD2_BK0_PORCTRL,
+		   DSI_CMD2_BK0_PORCTRL_B0(mode),
+		   DSI_CMD2_BK0_PORCTRL_B1(mode));
+	ST7701_DSI(st7701, DSI_CMD2_BK0_INVSEL,
+		   DSI_CMD2_BK0_INVSEL_B0, DSI_CMD2_BK0_INVSEL_B1);
+
+	/* Command2, BK1 */
+	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
+			0x77, 0x01, 0x00, 0x00, DSI_CMD2BK1_SEL);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_VRHS, DSI_CMD2_BK1_VRHA_SET);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_VCOM, DSI_CMD2_BK1_VCOM_SET);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_VGHSS, DSI_CMD2_BK1_VGHSS_SET);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_TESTCMD, DSI_CMD2_BK1_TESTCMD_VAL);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_VGLS, DSI_CMD2_BK1_VGLS_SET);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_PWCTLR1, DSI_CMD2_BK1_PWCTLR1_SET);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_PWCTLR2, DSI_CMD2_BK1_PWCTLR2_SET);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_SPD1, DSI_CMD2_BK1_SPD1_SET);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_SPD2, DSI_CMD2_BK1_SPD2_SET);
+	ST7701_DSI(st7701, DSI_CMD2_BK1_MIPISET1, DSI_CMD2_BK1_MIPISET1_SET);
+
+	/**
+	 * ST7701_SPEC_V1.2 is unable to provide enough information above this
+	 * specific command sequence, so grab the same from vendor BSP driver.
+	 */
+	ST7701_DSI(st7701, 0xE0, 0x00, 0x00, 0x02);
+	ST7701_DSI(st7701, 0xE1, 0x0B, 0x00, 0x0D, 0x00, 0x0C, 0x00, 0x0E,
+		   0x00, 0x00, 0x44, 0x44);
+	ST7701_DSI(st7701, 0xE2, 0x33, 0x33, 0x44, 0x44, 0x64, 0x00, 0x66,
+		   0x00, 0x65, 0x00, 0x67, 0x00, 0x00);
+	ST7701_DSI(st7701, 0xE3, 0x00, 0x00, 0x33, 0x33);
+	ST7701_DSI(st7701, 0xE4, 0x44, 0x44);
+	ST7701_DSI(st7701, 0xE5, 0x0C, 0x78, 0x3C, 0xA0, 0x0E, 0x78, 0x3C,
+		   0xA0, 0x10, 0x78, 0x3C, 0xA0, 0x12, 0x78, 0x3C, 0xA0);
+	ST7701_DSI(st7701, 0xE6, 0x00, 0x00, 0x33, 0x33);
+	ST7701_DSI(st7701, 0xE7, 0x44, 0x44);
+	ST7701_DSI(st7701, 0xE8, 0x0D, 0x78, 0x3C, 0xA0, 0x0F, 0x78, 0x3C,
+		   0xA0, 0x11, 0x78, 0x3C, 0xA0, 0x13, 0x78, 0x3C, 0xA0);
+	ST7701_DSI(st7701, 0xEB, 0x02, 0x02, 0x39, 0x39, 0xEE, 0x44, 0x00);
+	ST7701_DSI(st7701, 0xEC, 0x00, 0x00);
+	ST7701_DSI(st7701, 0xED, 0xFF, 0xF1, 0x04, 0x56, 0x72, 0x3F, 0xFF,
+		   0xFF, 0xFF, 0xFF, 0xF3, 0x27, 0x65, 0x40, 0x1F, 0xFF);
+
+	/* disable Command2 */
+	ST7701_DSI(st7701, DSI_CMD2BKX_SEL,
+		   0x77, 0x01, 0x00, 0x00, DSI_CMD2BKX_SEL_NONE);
+}
+
+static int st7701_prepare(struct drm_panel *panel)
+{
+	struct st7701 *st7701 = panel_to_st7701(panel);
+	int ret;
+
+	gpiod_set_value(st7701->reset, 0);
+
+	ret = regulator_bulk_enable(st7701->desc->num_supplies,
+				    st7701->supplies);
+	if (ret < 0)
+		return ret;
+	msleep(20);
+
+	gpiod_set_value(st7701->reset, 1);
+	msleep(150);
+
+	st7701_init_sequence(st7701);
+
+	return 0;
+}
+
+static int st7701_enable(struct drm_panel *panel)
+{
+	struct st7701 *st7701 = panel_to_st7701(panel);
+
+	ST7701_DSI(st7701, MIPI_DCS_SET_DISPLAY_ON, 0x00);
+	backlight_enable(st7701->backlight);
+
+	return 0;
+}
+
+static int st7701_disable(struct drm_panel *panel)
+{
+	struct st7701 *st7701 = panel_to_st7701(panel);
+
+	backlight_disable(st7701->backlight);
+	ST7701_DSI(st7701, MIPI_DCS_SET_DISPLAY_OFF, 0x00);
+
+	return 0;
+}
+
+static int st7701_unprepare(struct drm_panel *panel)
+{
+	struct st7701 *st7701 = panel_to_st7701(panel);
+
+	ST7701_DSI(st7701, MIPI_DCS_ENTER_SLEEP_MODE, 0x00);
+
+	msleep(st7701->sleep_delay);
+
+	gpiod_set_value(st7701->reset, 0);
+
+	/**
+	 * During the Resetting period, the display will be blanked
+	 * (The display is entering blanking sequence, which maximum
+	 * time is 120 ms, when Reset Starts in Sleep Out –mode. The
+	 * display remains the blank state in Sleep In –mode.) and
+	 * then return to Default condition for Hardware Reset.
+	 *
+	 * So we need wait sleep_delay time to make sure reset completed.
+	 */
+	msleep(st7701->sleep_delay);
+
+	regulator_bulk_disable(st7701->desc->num_supplies, st7701->supplies);
+
+	return 0;
+}
+
+static int st7701_get_modes(struct drm_panel *panel)
+{
+	struct st7701 *st7701 = panel_to_st7701(panel);
+	const struct drm_display_mode *desc_mode = st7701->desc->mode;
+	struct drm_display_mode *mode;
+
+	mode = drm_mode_duplicate(panel->drm, desc_mode);
+	if (!mode) {
+		DRM_DEV_ERROR(&st7701->dsi->dev,
+			      "failed to add mode %ux%ux@%u\n",
+			      desc_mode->hdisplay, desc_mode->vdisplay,
+			      desc_mode->vrefresh);
+		return -ENOMEM;
+	}
+
+	drm_mode_set_name(mode);
+	drm_mode_probed_add(panel->connector, mode);
+
+	panel->connector->display_info.width_mm = desc_mode->width_mm;
+	panel->connector->display_info.height_mm = desc_mode->height_mm;
+
+	return 1;
+}
+
+static const struct drm_panel_funcs st7701_funcs = {
+	.disable	= st7701_disable,
+	.unprepare	= st7701_unprepare,
+	.prepare	= st7701_prepare,
+	.enable		= st7701_enable,
+	.get_modes	= st7701_get_modes,
+};
+
+static const struct drm_display_mode ts8550b_mode = {
+	.clock		= 27500,
+
+	.hdisplay	= 480,
+	.hsync_start	= 480 + 38,
+	.hsync_end	= 480 + 38 + 12,
+	.htotal		= 480 + 38 + 12 + 12,
+
+	.vdisplay	= 854,
+	.vsync_start	= 854 + 4,
+	.vsync_end	= 854 + 4 + 8,
+	.vtotal		= 854 + 4 + 8 + 18,
+
+	.width_mm	= 69,
+	.height_mm	= 139,
+
+	.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
+};
+
+static const char * const ts8550b_supply_names[] = {
+	"VCC",
+	"IOVCC",
+};
+
+static const struct st7701_panel_desc ts8550b_desc = {
+	.mode = &ts8550b_mode,
+	.lanes = 2,
+	.flags = MIPI_DSI_MODE_VIDEO,
+	.format = MIPI_DSI_FMT_RGB888,
+	.supply_names = ts8550b_supply_names,
+	.num_supplies = ARRAY_SIZE(ts8550b_supply_names),
+	.panel_sleep_delay = 80, /* panel need extra 80ms for sleep out cmd */
+};
+
+static int st7701_dsi_probe(struct mipi_dsi_device *dsi)
+{
+	const struct st7701_panel_desc *desc;
+	struct st7701 *st7701;
+	int ret, i;
+
+	st7701 = devm_kzalloc(&dsi->dev, sizeof(*st7701), GFP_KERNEL);
+	if (!st7701)
+		return -ENOMEM;
+
+	desc = of_device_get_match_data(&dsi->dev);
+	dsi->mode_flags = desc->flags;
+	dsi->format = desc->format;
+	dsi->lanes = desc->lanes;
+
+	st7701->supplies = devm_kcalloc(&dsi->dev, desc->num_supplies,
+					sizeof(*st7701->supplies),
+					GFP_KERNEL);
+	if (!st7701->supplies)
+		return -ENOMEM;
+
+	for (i = 0; i < desc->num_supplies; i++)
+		st7701->supplies[i].supply = desc->supply_names[i];
+
+	ret = devm_regulator_bulk_get(&dsi->dev, desc->num_supplies,
+				      st7701->supplies);
+	if (ret < 0)
+		return ret;
+
+	st7701->reset = devm_gpiod_get(&dsi->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(st7701->reset)) {
+		DRM_DEV_ERROR(&dsi->dev, "Couldn't get our reset GPIO\n");
+		return PTR_ERR(st7701->reset);
+	}
+
+	st7701->backlight = devm_of_find_backlight(&dsi->dev);
+	if (IS_ERR(st7701->backlight))
+		return PTR_ERR(st7701->backlight);
+
+	drm_panel_init(&st7701->panel);
+
+	/**
+	 * Once sleep out has been issued, ST7701 IC required to wait 120ms
+	 * before initiating new commands.
+	 *
+	 * On top of that some panels might need an extra delay to wait, so
+	 * add panel specific delay for those cases. As now this panel specific
+	 * delay information is referenced from those panel BSP driver, example
+	 * ts8550b and there is no valid documentation for that.
+	 */
+	st7701->sleep_delay = 120 + desc->panel_sleep_delay;
+	st7701->panel.funcs = &st7701_funcs;
+	st7701->panel.dev = &dsi->dev;
+
+	ret = drm_panel_add(&st7701->panel);
+	if (ret < 0)
+		return ret;
+
+	mipi_dsi_set_drvdata(dsi, st7701);
+	st7701->dsi = dsi;
+	st7701->desc = desc;
+
+	return mipi_dsi_attach(dsi);
+}
+
+static int st7701_dsi_remove(struct mipi_dsi_device *dsi)
+{
+	struct st7701 *st7701 = mipi_dsi_get_drvdata(dsi);
+
+	mipi_dsi_detach(dsi);
+	drm_panel_remove(&st7701->panel);
+
+	if (st7701->backlight)
+		put_device(&st7701->backlight->dev);
+
+	return 0;
+}
+
+static const struct of_device_id st7701_of_match[] = {
+	{ .compatible = "techstar,ts8550b", .data = &ts8550b_desc },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, st7701_of_match);
+
+static struct mipi_dsi_driver st7701_dsi_driver = {
+	.probe		= st7701_dsi_probe,
+	.remove		= st7701_dsi_remove,
+	.driver = {
+		.name		= "st7701",
+		.of_match_table	= st7701_of_match,
+	},
+};
+module_mipi_dsi_driver(st7701_dsi_driver);
+
+MODULE_AUTHOR("Jagan Teki <jagan@...rulasolutions.com>");
+MODULE_DESCRIPTION("Sitronix ST7701 LCD Panel Driver");
+MODULE_LICENSE("GPL");
-- 
2.18.0.321.gffc6fa0e3

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