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From:   Jagan Teki <jagan@amarulasolutions.com>
Date:   Wed, 21 Jul 2021 21:17:59 +0530
Message-ID: <CAMty3ZAsyT6aKxsphq70-K2D1jtooaOYZ+dr2SioxGEw-a8dZw@mail.gmail.com>
Subject: Re: [PATCH v2 3/3] drm/panel: Add ilitek ili9341 panel driver
To:     dillon.minfei@gmail.com
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Alexandre TORGUE <alexandre.torgue@foss.st.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        devicetree <devicetree@vger.kernel.org>,
        Douglas Anderson <dianders@chromium.org>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        =?UTF-8?Q?Noralf_Tr=C3=B8nnes?= <noralf@tronnes.org>,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
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Precedence: bulk

On Wed, Jul 21, 2021 at 1:11 PM <dillon.minfei@gmail.com> wrote:
>
> From: Dillon Min <dillon.minfei@gmail.com>
>
> This driver combine tiny/ili9341.c mipi_dbi_interface driver
> with mipi_dpi_interface driver, can support ili9341 with serial
> mode or parallel rgb interface mode by register configuration.
>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Signed-off-by: Dillon Min <dillon.minfei@gmail.com>
> ---
> changes in v2:
> - replace vcc regulator to three bulk regulators(vci, vddi, vddi-led)
>   according to linus suggestion, thanks.
>
>  drivers/gpu/drm/panel/Kconfig                |  12 +
>  drivers/gpu/drm/panel/Makefile               |   1 +
>  drivers/gpu/drm/panel/panel-ilitek-ili9341.c | 778 +++++++++++++++++++++++++++
>  3 files changed, 791 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-ilitek-ili9341.c
>
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index ef87d92cdf49..eb34b8d1b19a 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -124,6 +124,18 @@ config DRM_PANEL_ILITEK_IL9322
>           Say Y here if you want to enable support for Ilitek IL9322
>           QVGA (320x240) RGB, YUV and ITU-T BT.656 panels.
>
> +config DRM_PANEL_ILITEK_ILI9341
> +       tristate "Ilitek ILI9341 240x320 QVGA panels"
> +       depends on OF && SPI
> +       depends on DRM_KMS_HELPER
> +       depends on DRM_KMS_CMA_HELPER
> +       depends on BACKLIGHT_CLASS_DEVICE
> +       select DRM_MIPI_DBI
> +       help
> +         Say Y here if you want to enable support for Ilitek IL9341
> +         QVGA (240x320) RGB panels. support serial & parallel rgb
> +         interface.
> +
>  config DRM_PANEL_ILITEK_ILI9881C
>         tristate "Ilitek ILI9881C-based panels"
>         depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index cae4d976c069..0ecde184665d 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -11,6 +11,7 @@ obj-$(CONFIG_DRM_PANEL_ELIDA_KD35T133) += panel-elida-kd35t133.o
>  obj-$(CONFIG_DRM_PANEL_FEIXIN_K101_IM2BA02) += panel-feixin-k101-im2ba02.o
>  obj-$(CONFIG_DRM_PANEL_FEIYANG_FY07024DI26A30D) += panel-feiyang-fy07024di26a30d.o
>  obj-$(CONFIG_DRM_PANEL_ILITEK_IL9322) += panel-ilitek-ili9322.o
> +obj-$(CONFIG_DRM_PANEL_ILITEK_ILI9341) += panel-ilitek-ili9341.o
>  obj-$(CONFIG_DRM_PANEL_ILITEK_ILI9881C) += panel-ilitek-ili9881c.o
>  obj-$(CONFIG_DRM_PANEL_INNOLUX_P079ZCA) += panel-innolux-p079zca.o
>  obj-$(CONFIG_DRM_PANEL_JDI_LT070ME05000) += panel-jdi-lt070me05000.o
> diff --git a/drivers/gpu/drm/panel/panel-ilitek-ili9341.c b/drivers/gpu/drm/panel/panel-ilitek-ili9341.c
> new file mode 100644
> index 000000000000..717b0b930e2f
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-ilitek-ili9341.c
> @@ -0,0 +1,778 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Ilitek ILI9341 TFT LCD drm_panel driver.
> + *
> + * This panel can be configured to support:
> + * - 16-bit parallel RGB interface
> + * - 18-bit parallel RGB interface
> + * - 4-line serial spi interface
> + *
> + * Copyright (C) 2021 Dillon Min <dillon.minfei@gmail.com>
> + * Derived from drivers/drm/gpu/panel/panel-ilitek-ili9322.c
> + * the reuse of DBI abstraction part referred from Linus's patch
> + * "drm/panel: s6e63m0: Switch to DBI abstraction for SPI"
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +#include <linux/delay.h>
> +#include <video/mipi_display.h>
> +#include <drm/drm_mipi_dbi.h>
> +#include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/drm_gem_cma_helper.h>
> +#include <drm/drm_fb_helper.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_gem_atomic_helper.h>
> +
> +#include <drm/drm_drv.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_print.h>
> +
> +#define ILI9341_RGB_INTERFACE  0xb0   /* RGB Interface Signal Control */
> +#define ILI9341_FRC            0xb1   /* Frame Rate Control register */
> +#define ILI9341_DFC            0xb6   /* Display Function Control register */
> +#define ILI9341_POWER1         0xc0   /* Power Control 1 register */
> +#define ILI9341_POWER2         0xc1   /* Power Control 2 register */
> +#define ILI9341_VCOM1          0xc5   /* VCOM Control 1 register */
> +#define ILI9341_VCOM2          0xc7   /* VCOM Control 2 register */
> +#define ILI9341_POWERA         0xcb   /* Power control A register */
> +#define ILI9341_POWERB         0xcf   /* Power control B register */
> +#define ILI9341_PGAMMA         0xe0   /* Positive Gamma Correction register */
> +#define ILI9341_NGAMMA         0xe1   /* Negative Gamma Correction register */
> +#define ILI9341_DTCA           0xe8   /* Driver timing control A */
> +#define ILI9341_DTCB           0xea   /* Driver timing control B */
> +#define ILI9341_POWER_SEQ      0xed   /* Power on sequence register */
> +#define ILI9341_3GAMMA_EN      0xf2   /* 3 Gamma enable register */
> +#define ILI9341_INTERFACE      0xf6   /* Interface control register */
> +#define ILI9341_PRC            0xf7   /* Pump ratio control register */
> +#define ILI9341_ETMOD         0xb7   /* Entry mode set */
> +
> +#define ILI9341_MADCTL_BGR     BIT(3)
> +#define ILI9341_MADCTL_MV      BIT(5)
> +#define ILI9341_MADCTL_MX      BIT(6)
> +#define ILI9341_MADCTL_MY      BIT(7)
> +
> +#define ILI9341_POWER_B_LEN    3
> +#define ILI9341_POWER_SEQ_LEN  4
> +#define ILI9341_DTCA_LEN       3
> +#define ILI9341_DTCB_LEN       2
> +#define ILI9341_POWER_A_LEN    5
> +#define ILI9341_DFC_1_LEN      2
> +#define ILI9341_FRC_LEN                2
> +#define ILI9341_VCOM_1_LEN     2
> +#define ILI9341_DFC_2_LEN      4
> +#define ILI9341_COLUMN_ADDR_LEN        4
> +#define ILI9341_PAGE_ADDR_LEN  4
> +#define ILI9341_INTERFACE_LEN  3
> +#define ILI9341_PGAMMA_LEN     15
> +#define ILI9341_NGAMMA_LEN     15
> +#define ILI9341_CA_LEN         3
> +
> +#define ILI9341_PIXEL_DPI_16_BITS      (BIT(6) | BIT(4))
> +#define ILI9341_PIXEL_DPI_18_BITS      (BIT(6) | BIT(5))
> +#define ILI9341_GAMMA_CURVE_1          BIT(0)
> +#define ILI9341_IF_WE_MODE             BIT(0)
> +#define ILI9341_IF_BIG_ENDIAN          0x00
> +#define ILI9341_IF_DM_RGB              BIT(2)
> +#define ILI9341_IF_DM_INTERNAL         0x00
> +#define ILI9341_IF_DM_VSYNC            BIT(3)
> +#define ILI9341_IF_RM_RGB              BIT(1)
> +#define ILI9341_IF_RIM_RGB             0x00
> +
> +#define ILI9341_COLUMN_ADDR            0x00ef
> +#define ILI9341_PAGE_ADDR              0x013f
> +
> +#define ILI9341_RGB_EPL                        BIT(0)
> +#define ILI9341_RGB_DPL                        BIT(1)
> +#define ILI9341_RGB_HSPL               BIT(2)
> +#define ILI9341_RGB_VSPL               BIT(3)
> +#define ILI9341_RGB_DE_MODE            BIT(6)
> +#define ILI9341_RGB_DISP_PATH_MEM      BIT(7)
> +
> +#define ILI9341_DBI_VCOMH_4P6V         0x23
> +#define ILI9341_DBI_PWR_2_DEFAULT      0x10
> +#define ILI9341_DBI_PRC_NORMAL         0x20
> +#define ILI9341_DBI_VCOM_1_VMH_4P25V   0x3e
> +#define ILI9341_DBI_VCOM_1_VML_1P5V    0x28
> +#define ILI9341_DBI_VCOM_2_DEC_58      0x86
> +#define ILI9341_DBI_FRC_DIVA           0x00
> +#define ILI9341_DBI_FRC_RTNA           0x1b
> +#define ILI9341_DBI_EMS_GAS            BIT(0)
> +#define ILI9341_DBI_EMS_DTS            BIT(1)
> +#define ILI9341_DBI_EMS_GON            BIT(2)
> +
> +/**
> + * struct ili9341_config - the system specific ILI9341 configuration
> + * @max_spi_speed: 10000000
> + */
> +struct ili9341_config {
> +       u32 max_spi_speed;
> +       /** @mode: the drm display mode */
> +       const struct drm_display_mode mode;
> +       /** @ca: TODO: need comments for this register */
> +       u8 ca[ILI9341_CA_LEN];
> +       /** @power_b: TODO: need comments for this register */
> +       u8 power_b[ILI9341_POWER_B_LEN];
> +       /** @power_seq: TODO: need comments for this register */
> +       u8 power_seq[ILI9341_POWER_SEQ_LEN];
> +       /** @dtca: TODO: need comments for this register */
> +       u8 dtca[ILI9341_DTCA_LEN];
> +       /** @dtcb: TODO: need comments for this register */
> +       u8 dtcb[ILI9341_DTCB_LEN];
> +       /** @power_a: TODO: need comments for this register */
> +       u8 power_a[ILI9341_POWER_A_LEN];
> +       /** @frc: Frame Rate Control (In Normal Mode/Full Colors) (B1h) */
> +       u8 frc[ILI9341_FRC_LEN];
> +       /** @prc: TODO: need comments for this register */
> +       u8 prc;
> +       /** @dfc_1: B6h DISCTRL (Display Function Control) */
> +       u8 dfc_1[ILI9341_DFC_1_LEN];
> +       /** @power_1: Power Control 1 (C0h) */
> +       u8 power_1;
> +       /** @power_2: Power Control 2 (C1h) */
> +       u8 power_2;
> +       /** @vcom_1: VCOM Control 1(C5h) */
> +       u8 vcom_1[ILI9341_VCOM_1_LEN];
> +       /** @vcom_2: VCOM Control 2(C7h) */
> +       u8 vcom_2;
> +       /** @address_mode: Memory Access Control (36h) */
> +       u8 address_mode;
> +       /** @g3amma_en: TODO: need comments for this register */
> +       u8 g3amma_en;
> +       /** @rgb_interface: RGB Interface Signal Control (B0h) */
> +       u8 rgb_interface;
> +       /** @dfc_2: refer to dfc_1 */
> +       u8 dfc_2[ILI9341_DFC_2_LEN];
> +       /** @column_addr: Column Address Set (2Ah) */
> +       u8 column_addr[ILI9341_COLUMN_ADDR_LEN];
> +       /** @page_addr: Page Address Set (2Bh) */
> +       u8 page_addr[ILI9341_PAGE_ADDR_LEN];
> +       /** @interface: Interface Control (F6h) */
> +       u8 interface[ILI9341_INTERFACE_LEN];
> +       /** @pixel_format: This command sets the pixel format for the RGB */
> +       /* image data used by
> +        */
> +       u8 pixel_format;
> +       /** @gamma_curve: This command is used to select the desired Gamma */
> +       /* curve for the
> +        */
> +       u8 gamma_curve;
> +       /** @pgamma: Positive Gamma Correction (E0h) */
> +       u8 pgamma[ILI9341_PGAMMA_LEN];
> +       /** @ngamma: Negative Gamma Correction (E1h) */
> +       u8 ngamma[ILI9341_NGAMMA_LEN];
> +};
> +
> +struct ili9341 {
> +       struct device *dev;
> +       const struct ili9341_config *conf;
> +       struct drm_panel panel;
> +       struct gpio_desc *reset_gpio;
> +       struct gpio_desc *dc_gpio;
> +       struct mipi_dbi *dbi;
> +       u32 max_spi_speed;
> +       struct regulator_bulk_data supplies[3];
> +};
> +
> +/*
> + * The Stm32f429-disco board has a panel ili9341 connected to ltdc controller
> + */
> +static const struct ili9341_config ili9341_stm32f429_disco_data = {
> +       .max_spi_speed = 10000000,
> +       .mode = {
> +               .clock = 6100,
> +               .hdisplay = 240,
> +               .hsync_start = 240 + 10,/* hfp 10 */
> +               .hsync_end = 240 + 10 + 10,/* hsync 10 */
> +               .htotal = 240 + 10 + 10 + 20,/* hbp 20 */
> +               .vdisplay = 320,
> +               .vsync_start = 320 + 4,/* vfp 4 */
> +               .vsync_end = 320 + 4 + 2,/* vsync 2 */
> +               .vtotal = 320 + 4 + 2 + 2,/* vbp 2 */
> +               .flags = 0,
> +               .width_mm = 65,
> +               .height_mm = 50,
> +               .type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
> +       },
> +       .ca = {0xc3, 0x08, 0x50},
> +       .power_b = {0x00, 0xc1, 0x30},
> +       .power_seq = {0x64, 0x03, 0x12, 0x81},
> +       .dtca = {0x85, 0x00, 0x78},
> +       .power_a = {0x39, 0x2c, 0x00, 0x34, 0x02},
> +       .prc = 0x20,
> +       .dtcb = {0x00, 0x00},
> +       /* 0x00 fosc, 0x1b 70hz */
> +       .frc = {0x00, 0x1b},
> +       /* 0x0a Interval scan, AGND AGND AGND AGND
> +        * 0xa2 Normally white, G1 -> G320, S720 -> S1,
> +        *      Scan Cycle 5 frames,85ms
> +        */
> +       .dfc_1 = {0x0a, 0xa2},
> +       /* 0x10 3.65v */
> +       .power_1 = 0x10,
> +       /* 0x10 AVDD=vci*2, VGH=vci*7, VGL=-vci*4 */
> +       .power_2 = 0x10,
> +       /* 0x45 VCOMH 4.425v, 0x15 VCOML -1.975*/
> +       .vcom_1 = {0x45, 0x15},
> +       /* 0x90 offset voltage, VMH-48, VML-48 */
> +       .vcom_2 = 0x90,
> +       /* 0xc8 Row Address Order, Column Address Order
> +        * BGR 1
> +        */
> +       .address_mode = 0xc8,
> +       .g3amma_en = 0x00,
> +       /* 0xc2
> +        * Display Data Path: Memory
> +        * RGB: DE mode
> +        * DOTCLK polarity set (data fetched at the falling time)
> +        */
> +       .rgb_interface = ILI9341_RGB_DISP_PATH_MEM |
> +                       ILI9341_RGB_DE_MODE |
> +                       ILI9341_RGB_DPL,
> +       /*
> +        * 0x0a
> +        * Gate outputs in non-display area: Interval scan
> +        * Determine source/VCOM output in a non-display area in the partial
> +        * display mode: AGND AGND AGND AGND
> +        *
> +        * 0xa7
> +        * Scan Cycle: 15 frames
> +        * fFLM = 60Hz: 255ms
> +        * Liquid crystal type: Normally white
> +        * Gate Output Scan Direction: G1 -> G320
> +        * Source Output Scan Direction: S720 -> S1
> +        *
> +        * 0x27
> +        * LCD Driver Line: 320 lines
> +        *
> +        * 0x04
> +        * PCDIV: 4
> +        */
> +       .dfc_2 = {0x0a, 0xa7, 0x27, 0x04},
> +       /* column address: 240 */
> +       .column_addr = {0x00, 0x00, (ILI9341_COLUMN_ADDR >> 4) & 0xff,
> +                               ILI9341_COLUMN_ADDR & 0xff},
> +       /* page address: 320 */
> +       .page_addr = {0x00, 0x00, (ILI9341_PAGE_ADDR >> 4) & 0xff,
> +                               ILI9341_PAGE_ADDR & 0xff},
> +       /* Memory write control: When the transfer number of data exceeds
> +        * (EC-SC+1)*(EP-SP+1), the column and page number will be
> +        * reset, and the exceeding data will be written into the following
> +        * column and page.
> +        * Display Operation Mode: RGB Interface Mode
> +        * Interface for RAM Access: RGB interface
> +        * 16- bit RGB interface (1 transfer/pixel)
> +        */
> +       .interface = {ILI9341_IF_WE_MODE, 0x00,
> +                       ILI9341_IF_DM_RGB | ILI9341_IF_RM_RGB},
> +       /* DPI: 16 bits / pixel */
> +       .pixel_format = ILI9341_PIXEL_DPI_16_BITS,
> +       /* Curve Selected: Gamma curve 1 (G2.2) */
> +       .gamma_curve = ILI9341_GAMMA_CURVE_1,
> +       .pgamma = {0x0f, 0x29, 0x24, 0x0c, 0x0e,
> +                       0x09, 0x4e, 0x78, 0x3c, 0x09,
> +                       0x13, 0x05, 0x17, 0x11, 0x00},
> +       .ngamma = {0x00, 0x16, 0x1b, 0x04, 0x11,
> +                       0x07, 0x31, 0x33, 0x42, 0x05,
> +                       0x0c, 0x0a, 0x28, 0x2f, 0x0f},
> +};
> +
> +static inline struct ili9341 *panel_to_ili9341(struct drm_panel *panel)
> +{
> +       return container_of(panel, struct ili9341, panel);
> +}
> +
> +static void ili9341_dpi_init(struct ili9341 *ili)
> +{
> +       struct mipi_dbi *dbi = ili->dbi;
> +       struct ili9341_config *cfg = (struct ili9341_config *)ili->conf;
> +
> +       /* Power Control */
> +       mipi_dbi_command_stackbuf(dbi, 0xca, cfg->ca, ILI9341_CA_LEN);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_POWERB, cfg->power_b,
> +                                 ILI9341_POWER_B_LEN);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_POWER_SEQ, cfg->power_seq,
> +                                 ILI9341_POWER_SEQ_LEN);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_DTCA, cfg->dtca,
> +                                 ILI9341_DTCA_LEN);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_POWERA, cfg->power_a,
> +                                 ILI9341_POWER_A_LEN);
> +       mipi_dbi_command(ili->dbi, ILI9341_PRC, cfg->prc);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_DTCB, cfg->dtcb,
> +                                 ILI9341_DTCB_LEN);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_FRC, cfg->frc, ILI9341_FRC_LEN);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_DFC, cfg->dfc_1,
> +                                 ILI9341_DFC_1_LEN);
> +       mipi_dbi_command(dbi, ILI9341_POWER1, cfg->power_1);
> +       mipi_dbi_command(dbi, ILI9341_POWER2, cfg->power_2);
> +
> +       /* VCOM */
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_VCOM1, cfg->vcom_1,
> +                                 ILI9341_VCOM_1_LEN);
> +       mipi_dbi_command(dbi, ILI9341_VCOM2, cfg->vcom_2);
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, cfg->address_mode);
> +
> +       /* Gamma */
> +       mipi_dbi_command(dbi, ILI9341_3GAMMA_EN, cfg->g3amma_en);
> +       mipi_dbi_command(dbi, ILI9341_RGB_INTERFACE, cfg->rgb_interface);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_DFC, cfg->dfc_2,
> +                                 ILI9341_DFC_2_LEN);
> +
> +       /* Colomn address set */
> +       mipi_dbi_command_stackbuf(dbi, MIPI_DCS_SET_COLUMN_ADDRESS,
> +                                 cfg->column_addr, ILI9341_COLUMN_ADDR_LEN);
> +
> +       /* Page address set */
> +       mipi_dbi_command_stackbuf(dbi, MIPI_DCS_SET_PAGE_ADDRESS,
> +                                 cfg->page_addr, ILI9341_PAGE_ADDR_LEN);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_INTERFACE, cfg->interface,
> +                                 ILI9341_INTERFACE_LEN);
> +
> +       /* Format */
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_PIXEL_FORMAT, cfg->pixel_format);
> +       mipi_dbi_command(dbi, MIPI_DCS_WRITE_MEMORY_START);
> +       msleep(200);
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_GAMMA_CURVE, cfg->gamma_curve);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_PGAMMA, cfg->pgamma,
> +                                 ILI9341_PGAMMA_LEN);
> +       mipi_dbi_command_stackbuf(dbi, ILI9341_NGAMMA, cfg->ngamma,
> +                                 ILI9341_NGAMMA_LEN);
> +       mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
> +       msleep(200);
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
> +       mipi_dbi_command(dbi, MIPI_DCS_WRITE_MEMORY_START);
> +
> +       dev_info(ili->dev, "initialized display rgb interface\n");
> +}
> +
> +static int ili9341_dpi_power_on(struct ili9341 *ili)
> +{
> +       int ret = 0;
> +
> +       /* Assert RESET */
> +       gpiod_set_value(ili->reset_gpio, 1);
> +
> +       /* Enable power */
> +       ret = regulator_bulk_enable(ARRAY_SIZE(ili->supplies),
> +                                   ili->supplies);
> +       if (ret < 0) {
> +               dev_err(ili->dev, "unable to enable vcc\n");
> +               return ret;
> +       }
> +       msleep(20);
> +
> +       /* De-assert RESET */
> +       gpiod_set_value(ili->reset_gpio, 0);
> +       msleep(20);
> +
> +       return 0;
> +}
> +
> +static int ili9341_dpi_power_off(struct ili9341 *ili)
> +{
> +       /* Assert RESET */
> +       gpiod_set_value(ili->reset_gpio, 1);
> +
> +       /* Disable power */
> +       return regulator_bulk_disable(ARRAY_SIZE(ili->supplies),
> +                                     ili->supplies);
> +}
> +
> +static int ili9341_dpi_disable(struct drm_panel *panel)
> +{
> +       struct ili9341 *ili = panel_to_ili9341(panel);
> +
> +       mipi_dbi_command(ili->dbi, MIPI_DCS_SET_DISPLAY_OFF);
> +       return 0;
> +}
> +
> +static int ili9341_dpi_unprepare(struct drm_panel *panel)
> +{
> +       struct ili9341 *ili = panel_to_ili9341(panel);
> +
> +       return ili9341_dpi_power_off(ili);
> +}
> +
> +static int ili9341_dpi_prepare(struct drm_panel *panel)
> +{
> +       struct ili9341 *ili = panel_to_ili9341(panel);
> +       int ret;
> +
> +       ret = ili9341_dpi_power_on(ili);
> +       if (ret < 0)
> +               return ret;
> +
> +       ili9341_dpi_init(ili);
> +
> +       return ret;
> +}
> +
> +static int ili9341_dpi_enable(struct drm_panel *panel)
> +{
> +       struct ili9341 *ili = panel_to_ili9341(panel);
> +
> +       mipi_dbi_command(ili->dbi, MIPI_DCS_SET_DISPLAY_ON);
> +       return 0;
> +}
> +
> +static int ili9341_dpi_get_modes(struct drm_panel *panel,
> +                                struct drm_connector *connector)
> +{
> +       struct ili9341 *ili = panel_to_ili9341(panel);
> +       struct drm_device *drm = connector->dev;
> +       struct drm_display_mode *mode;
> +       struct drm_display_info *info;
> +
> +       info = &connector->display_info;
> +       info->width_mm = ili->conf->mode.width_mm;
> +       info->height_mm = ili->conf->mode.height_mm;
> +
> +       if (ili->conf->rgb_interface & ILI9341_RGB_DPL)
> +               info->bus_flags |= DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE;
> +       else
> +               info->bus_flags |= DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
> +
> +       if (ili->conf->rgb_interface & ILI9341_RGB_EPL)
> +               info->bus_flags |= DRM_BUS_FLAG_DE_LOW;
> +       else
> +               info->bus_flags |= DRM_BUS_FLAG_DE_HIGH;
> +
> +       mode = drm_mode_duplicate(drm, &ili->conf->mode);
> +       if (!mode) {
> +               DRM_ERROR("bad mode or failed to add mode\n");
> +               return -EINVAL;
> +       }
> +       drm_mode_set_name(mode);
> +
> +       /* Set up the polarity */
> +       if (ili->conf->rgb_interface & ILI9341_RGB_HSPL)
> +               mode->flags |= DRM_MODE_FLAG_PHSYNC;
> +       else
> +               mode->flags |= DRM_MODE_FLAG_NHSYNC;
> +
> +       if (ili->conf->rgb_interface & ILI9341_RGB_VSPL)
> +               mode->flags |= DRM_MODE_FLAG_PVSYNC;
> +       else
> +               mode->flags |= DRM_MODE_FLAG_NVSYNC;
> +
> +       drm_mode_probed_add(connector, mode);
> +
> +       return 1; /* Number of modes */
> +}
> +
> +static const struct drm_panel_funcs ili9341_dpi_funcs = {
> +       .disable = ili9341_dpi_disable,
> +       .unprepare = ili9341_dpi_unprepare,
> +       .prepare = ili9341_dpi_prepare,
> +       .enable = ili9341_dpi_enable,
> +       .get_modes = ili9341_dpi_get_modes,
> +};
> +
> +static void ili9341_dbi_enable(struct drm_simple_display_pipe *pipe,
> +                              struct drm_crtc_state *crtc_state,
> +                              struct drm_plane_state *plane_state)
> +{
> +       struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(pipe->crtc.dev);
> +       struct mipi_dbi *dbi = &dbidev->dbi;
> +       u8 addr_mode;
> +       int ret, idx;
> +
> +       if (!drm_dev_enter(pipe->crtc.dev, &idx))
> +               return;
> +
> +       DRM_DEBUG_KMS("\n");
> +
> +       ret = mipi_dbi_poweron_conditional_reset(dbidev);
> +       if (ret < 0)
> +               goto out_exit;
> +       if (ret == 1)
> +               goto out_enable;
> +
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_OFF);
> +
> +       mipi_dbi_command(dbi, ILI9341_POWERB, 0x00, 0xc1, 0x30);
> +       mipi_dbi_command(dbi, ILI9341_POWER_SEQ, 0x64, 0x03, 0x12, 0x81);
> +       mipi_dbi_command(dbi, ILI9341_DTCA, 0x85, 0x00, 0x78);
> +       mipi_dbi_command(dbi, ILI9341_POWERA, 0x39, 0x2c, 0x00, 0x34, 0x02);
> +       mipi_dbi_command(dbi, ILI9341_PRC, ILI9341_DBI_PRC_NORMAL);
> +       mipi_dbi_command(dbi, ILI9341_DTCB, 0x00, 0x00);
> +
> +       /* Power Control */
> +       mipi_dbi_command(dbi, ILI9341_POWER1, ILI9341_DBI_VCOMH_4P6V);
> +       mipi_dbi_command(dbi, ILI9341_POWER2, ILI9341_DBI_PWR_2_DEFAULT);
> +       /* VCOM */
> +       mipi_dbi_command(dbi, ILI9341_VCOM1, ILI9341_DBI_VCOM_1_VMH_4P25V,
> +                        ILI9341_DBI_VCOM_1_VML_1P5V);
> +       mipi_dbi_command(dbi, ILI9341_VCOM2, ILI9341_DBI_VCOM_2_DEC_58);
> +
> +       /* Memory Access Control */
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_PIXEL_FORMAT,
> +                        MIPI_DCS_PIXEL_FMT_16BIT);
> +
> +       /* Frame Rate */
> +       mipi_dbi_command(dbi, ILI9341_FRC, ILI9341_DBI_FRC_DIVA & 0x03,
> +                        ILI9341_DBI_FRC_RTNA & 0x1f);
> +
> +       /* Gamma */
> +       mipi_dbi_command(dbi, ILI9341_3GAMMA_EN, 0x00);
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_GAMMA_CURVE, ILI9341_GAMMA_CURVE_1);
> +       mipi_dbi_command(dbi, ILI9341_PGAMMA,
> +                        0x0f, 0x31, 0x2b, 0x0c, 0x0e, 0x08, 0x4e, 0xf1,
> +                        0x37, 0x07, 0x10, 0x03, 0x0e, 0x09, 0x00);
> +       mipi_dbi_command(dbi, ILI9341_NGAMMA,
> +                        0x00, 0x0e, 0x14, 0x03, 0x11, 0x07, 0x31, 0xc1,
> +                        0x48, 0x08, 0x0f, 0x0c, 0x31, 0x36, 0x0f);
> +
> +       /* DDRAM */
> +       mipi_dbi_command(dbi, ILI9341_ETMOD, ILI9341_DBI_EMS_GAS |
> +                        ILI9341_DBI_EMS_DTS |
> +                        ILI9341_DBI_EMS_GON);
> +
> +       /* Display */
> +       mipi_dbi_command(dbi, ILI9341_DFC, 0x08, 0x82, 0x27, 0x00);
> +       mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
> +       msleep(100);
> +
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
> +       msleep(100);
> +
> +out_enable:
> +       switch (dbidev->rotation) {
> +       default:
> +               addr_mode = ILI9341_MADCTL_MX;
> +               break;
> +       case 90:
> +               addr_mode = ILI9341_MADCTL_MV;
> +               break;
> +       case 180:
> +               addr_mode = ILI9341_MADCTL_MY;
> +               break;
> +       case 270:
> +               addr_mode = ILI9341_MADCTL_MV | ILI9341_MADCTL_MY |
> +                           ILI9341_MADCTL_MX;
> +               break;
> +       }
> +       addr_mode |= ILI9341_MADCTL_BGR;
> +       mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, addr_mode);
> +       mipi_dbi_enable_flush(dbidev, crtc_state, plane_state);
> +       DRM_DEBUG_KMS("initialized display serial interface\n");
> +out_exit:
> +       drm_dev_exit(idx);
> +}
> +
> +static const struct drm_simple_display_pipe_funcs ili9341_dbi_funcs = {
> +       .enable = ili9341_dbi_enable,
> +       .disable = mipi_dbi_pipe_disable,
> +       .update = mipi_dbi_pipe_update,
> +       .prepare_fb = drm_gem_simple_display_pipe_prepare_fb,
> +};
> +
> +static const struct drm_display_mode ili9341_dbi_mode = {
> +       DRM_SIMPLE_MODE(240, 320, 37, 49),
> +};
> +
> +DEFINE_DRM_GEM_CMA_FOPS(ili9341_dbi_fops);
> +
> +static struct drm_driver ili9341_dbi_driver = {
> +       .driver_features        = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
> +       .fops                   = &ili9341_dbi_fops,
> +       DRM_GEM_CMA_DRIVER_OPS_VMAP,
> +       .debugfs_init           = mipi_dbi_debugfs_init,
> +       .name                   = "ili9341",
> +       .desc                   = "Ilitek ILI9341",
> +       .date                   = "20210716",
> +       .major                  = 1,
> +       .minor                  = 0,
> +};
> +
> +static int _ili9341_probe(struct spi_device *spi, bool dpi)
> +{
> +       struct gpio_desc *dc;
> +       struct gpio_desc *reset;
> +       struct device *dev = &spi->dev;
> +       int ret;
> +
> +       reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +       if (IS_ERR(reset))
> +               DRM_DEV_ERROR(dev, "Failed to get gpio 'reset'\n");
> +
> +       dc = devm_gpiod_get_optional(dev, "dc", GPIOD_OUT_LOW);
> +       if (IS_ERR(dc))
> +               DRM_DEV_ERROR(dev, "Failed to get gpio 'dc'\n");

Small nit. Moving the above dts parse code into the main probe and
have functions for dpi and !dpi would make code more readable.

Otherwise,
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>