[PATCH v4 2/3] drm: panel: Add Samsung S6E8FCO DSI controller for M1906F9 panel

Yedaya Katsman
2026-03-14T21:46:33Z

Add driver for Samsung S6E8FCO DSI controller for M1906F9 video mode panel,
found in Xiaomi Mi A3 mobile phone.

Co-developed-by: Kamil Gołda <kamil.golda@protonmail.com>
Signed-off-by: Kamil Gołda <kamil.golda@protonmail.com>
Signed-off-by: Yedaya Katsman <yedaya.ka@gmail.com>

---

The downstream dts claims a max brightness of 2047, but seems to ignore the
MSB.
---
MAINTAINERS | 5 +
drivers/gpu/drm/panel/Kconfig | 13 +
drivers/gpu/drm/panel/Makefile | 1 +
.../gpu/drm/panel/panel-samsung-s6e8fco-m1906f9.c | 301 +++++++++++++++++++++
4 files changed, 320 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index e087673237636268346979ddc270f8cf0905c722..0c835d432ced8cc1c8494596bc1c2a36eadd6fe8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8183,6 +8183,11 @@ S: Maintained
F: Documentation/devicetree/bindings/display/panel/samsung,s6e3ha8.yaml
F: drivers/gpu/drm/panel/panel-samsung-s6e3ha8.c

+DRM DRIVER FOR SAMSUNG S6E8FCO PANELS
+M: Yedaya Katsman <yedaya.ka@gmail.com>
+S: Maintained
+F: drivers/gpu/drm/panel/panel-samsung-s6e8fco-m1906f9.c
+
DRM DRIVER FOR SAMSUNG SOFEF00 DDIC
M: David Heidelberg <david@ixit.cz>
M: Casey Connolly <casey.connolly@linaro.org>
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 7a83804fedca1b688ce6fbe4295ec9009007e693..47a8a2d2535f3fa46fc4545ae30f7e0b6b3d2e1d 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -893,6 +893,19 @@ config DRM_PANEL_SAMSUNG_S6E8AA5X01_AMS561RA01
~5.6 inch AMOLED display, and the controller is driven by the MIPI
DSI protocol with 4 lanes.

+config DRM_PANEL_SAMSUNG_S6E8FCO
+ tristate "Samsung S6E8FCO DSI controller"
+ depends on OF
+ depends on BACKLIGHT_CLASS_DEVICE
+ select DRM_MIPI_DSI
+ help
+ Say Y or M here if you want to enable support for the Samsung
+ S6E8FCO DSI controller and connected panel.
+ Currently supported panels:
+
+ M1906F9 (M1906F9SH or M1906F9SI), 6.09 inch 720x1560, found
+ in the Xiaomi Mi A3 smartphone (xiaomi-laurel).
+
config DRM_PANEL_SAMSUNG_SOFEF00
tristate "Samsung SOFEF00 DSI panel controller"
depends on OF
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index b9562a6fdcb38bfd0dfee9e8c11e16149ada4386..0cf7f0fb4654eb3dc67b2f15294ea46015a9bcdc 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -91,6 +91,7 @@ obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E88A0_AMS427AP24) += panel-samsung-s6e88a0-ams4
obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E88A0_AMS452EF01) += panel-samsung-s6e88a0-ams452ef01.o
obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E8AA0) += panel-samsung-s6e8aa0.o
obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E8AA5X01_AMS561RA01) += panel-samsung-s6e8aa5x01-ams561ra01.o
+obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E8FCO) += panel-samsung-s6e8fco-m1906f9.o
obj-$(CONFIG_DRM_PANEL_SAMSUNG_SOFEF00) += panel-samsung-sofef00.o
obj-$(CONFIG_DRM_PANEL_SEIKO_43WVF1G) += panel-seiko-43wvf1g.o
obj-$(CONFIG_DRM_PANEL_SHARP_LQ079L1SX01) += panel-sharp-lq079l1sx01.o
diff --git a/drivers/gpu/drm/panel/panel-samsung-s6e8fco-m1906f9.c b/drivers/gpu/drm/panel/panel-samsung-s6e8fco-m1906f9.c
new file mode 100644
index 0000000000000000000000000000000000000000..7fabfe19b5728612ab2a2518a8a100e7010b1d0c
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-samsung-s6e8fco-m1906f9.c
@@ -0,0 +1,301 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) Kamil Gołda <kamil.golda@protonmail.com>
+// Copyright (c) Yedaya Katsman <yedaya.ka@gmail.com>
+// Generated with linux-mdss-dsi-panel-driver-generator from vendor device tree:
+// Copyright (c) The Linux Foundation. All rights reserved.
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+
+#include <video/mipi_display.h>
+
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_probe_helper.h>
+
+struct s6e8fco_ctx {
+ struct drm_panel panel;
+ struct mipi_dsi_device *dsi;
+ struct regulator_bulk_data *supplies;
+ struct gpio_desc *reset_gpio;
+};
+
+static const struct regulator_bulk_data s6e8fco_m1906f9_supplies[] = {
+ { .supply = "vdd" },
+ { .supply = "vci" },
+};
+
+static inline
+struct s6e8fco_ctx *to_s6e8fco_ctx(struct drm_panel *panel)
+{
+ return container_of_const(panel, struct s6e8fco_ctx, panel);
+}
+
+static void s6e8fco_m1906f9_reset(struct s6e8fco_ctx *ctx)
+{
+ gpiod_set_value_cansleep(ctx->reset_gpio, 0);
+ usleep_range(12000, 13000);
+ gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+ usleep_range(2000, 3000);
+ gpiod_set_value_cansleep(ctx->reset_gpio, 0);
+ usleep_range(10000, 11000);
+}
+
+#define s6e8fco_m1906f9_test_key_on_lvl2(ctx) \
+ mipi_dsi_dcs_write_seq_multi(ctx, 0xf0, 0x5a, 0x5a)
+#define s6e8fco_m1906f9_test_key_off_lvl2(ctx) \
+ mipi_dsi_dcs_write_seq_multi(ctx, 0xf0, 0xa5, 0xa5)
+#define s6e8fco_m1906f9_test_key_on_lvl3(ctx) \
+ mipi_dsi_dcs_write_seq_multi(ctx, 0xfc, 0x5a, 0x5a)
+#define s6e8fco_m1906f9_test_key_off_lvl3(ctx) \
+ mipi_dsi_dcs_write_seq_multi(ctx, 0xfc, 0xa5, 0xa5)
+
+static int s6e8fco_m1906f9_on(struct s6e8fco_ctx *ctx)
+{
+ struct mipi_dsi_multi_context dsi_ctx = { .dsi = ctx->dsi };
+
+ s6e8fco_m1906f9_test_key_on_lvl3(&dsi_ctx);
+
+ mipi_dsi_dcs_set_display_brightness_multi(&dsi_ctx, 0x0000);
+ mipi_dsi_dcs_write_seq_multi(&dsi_ctx, MIPI_DCS_WRITE_CONTROL_DISPLAY,
+ 0x20);
+ mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx);
+ mipi_dsi_msleep(&dsi_ctx, 50);
+ mipi_dsi_dcs_set_display_on_multi(&dsi_ctx);
+
+ mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb0, 0x04, 0xed);
+ mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xed,
+ 0xe4, 0x08, 0x96, 0xa4, 0x2a, 0x72, 0xe2,
+ 0xca, 0x00);
+ s6e8fco_m1906f9_test_key_off_lvl3(&dsi_ctx);
+ s6e8fco_m1906f9_test_key_on_lvl2(&dsi_ctx);
+ s6e8fco_m1906f9_test_key_on_lvl3(&dsi_ctx);
+ mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xe1, 0x93);
+ mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb0, 0x05, 0xf4);
+ mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf4, 0x03);
+ mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xed, 0x01, 0x81, 0x04);
+ s6e8fco_m1906f9_test_key_off_lvl2(&dsi_ctx);
+ s6e8fco_m1906f9_test_key_off_lvl3(&dsi_ctx);
+
+ return dsi_ctx.accum_err;
+}
+
+static int s6e8fco_m1906f9_off(struct s6e8fco_ctx *ctx)
+{
+ struct mipi_dsi_multi_context dsi_ctx = { .dsi = ctx->dsi };
+
+ mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
+ mipi_dsi_msleep(&dsi_ctx, 20);
+ mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx);
+ mipi_dsi_msleep(&dsi_ctx, 120);
+
+ return dsi_ctx.accum_err;
+}
+
+static int s6e8fco_m1906f9_prepare(struct drm_panel *panel)
+{
+ struct s6e8fco_ctx *ctx = to_s6e8fco_ctx(panel);
+ struct device *dev = &ctx->dsi->dev;
+ int ret;
+
+ ret = regulator_bulk_enable(ARRAY_SIZE(s6e8fco_m1906f9_supplies), ctx->supplies);
+ if (ret < 0) {
+ dev_err(dev, "Failed to enable regulators: %d\n", ret);
+ return ret;
+ }
+
+ s6e8fco_m1906f9_reset(ctx);
+
+ ret = s6e8fco_m1906f9_on(ctx);
+ if (ret < 0) {
+ dev_err(dev, "Failed to initialize panel: %d\n", ret);
+ gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+ regulator_bulk_disable(ARRAY_SIZE(s6e8fco_m1906f9_supplies), ctx->supplies);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int s6e8fco_m1906f9_unprepare(struct drm_panel *panel)
+{
+ struct s6e8fco_ctx *ctx = to_s6e8fco_ctx(panel);
+ struct device *dev = &ctx->dsi->dev;
+ int ret;
+
+ ret = s6e8fco_m1906f9_off(ctx);
+ if (ret < 0)
+ dev_err(dev, "Failed to un-initialize panel: %d\n", ret);
+
+ gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+ regulator_bulk_disable(ARRAY_SIZE(s6e8fco_m1906f9_supplies), ctx->supplies);
+
+ return 0;
+}
+
+static const struct drm_display_mode s6e8fco_m1906f9_samsungp_mode = {
+ .clock = (720 + 350 + 40 + 294) * (1560 + 17 + 2 + 5) * 60 / 1000,
+ .hdisplay = 720,
+ .hsync_start = 720 + 350,
+ .hsync_end = 720 + 350 + 40,
+ .htotal = 720 + 350 + 40 + 294,
+ .vdisplay = 1560,
+ .vsync_start = 1560 + 17,
+ .vsync_end = 1560 + 17 + 2,
+ .vtotal = 1560 + 17 + 2 + 5,
+ .width_mm = 65,
+ .height_mm = 140,
+ .type = DRM_MODE_TYPE_DRIVER,
+};
+
+static int s6e8fco_m1906f9_get_modes(struct drm_panel *panel,
+ struct drm_connector *connector)
+{
+ return drm_connector_helper_get_modes_fixed(connector, &s6e8fco_m1906f9_samsungp_mode);
+}
+
+static const struct drm_panel_funcs s6e8fco_m1906f9_panel_funcs = {
+ .prepare = s6e8fco_m1906f9_prepare,
+ .unprepare = s6e8fco_m1906f9_unprepare,
+ .get_modes = s6e8fco_m1906f9_get_modes,
+};
+
+static int s6e8fco_bl_update_status(struct backlight_device *bl)
+{
+ struct mipi_dsi_device *dsi = bl_get_data(bl);
+ u16 brightness = backlight_get_brightness(bl);
+ int ret;
+
+ dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+ ret = mipi_dsi_dcs_set_display_brightness_large(dsi, brightness);
+ if (ret < 0)
+ return ret;
+
+ dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+ return 0;
+}
+
+static int s6e8fco_bl_get_brightness(struct backlight_device *bl)
+{
+ struct mipi_dsi_device *dsi = bl_get_data(bl);
+ u16 brightness;
+ int ret;
+
+ dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+ ret = mipi_dsi_dcs_get_display_brightness_large(dsi, &brightness);
+ if (ret < 0)
+ return ret;
+
+ dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+ return brightness;
+}
+
+static const struct backlight_ops s6e8fco_bl_ops = {
+ .update_status = s6e8fco_bl_update_status,
+ .get_brightness = s6e8fco_bl_get_brightness,
+};
+
+static struct backlight_device *
+s6e8fco_m1906f9_create_backlight(struct mipi_dsi_device *dsi)
+{
+ struct device *dev = &dsi->dev;
+ const struct backlight_properties props = {
+ .type = BACKLIGHT_RAW,
+ .brightness = 512,
+ .max_brightness = 1023,
+ };
+
+ return devm_backlight_device_register(dev, dev_name(dev), dev, dsi,
+ &s6e8fco_bl_ops, &props);
+}
+
+static int s6e8fco_m1906f9_probe(struct mipi_dsi_device *dsi)
+{
+ struct device *dev = &dsi->dev;
+ struct s6e8fco_ctx *ctx;
+ int ret;
+
+ ctx = devm_drm_panel_alloc(dev, struct s6e8fco_ctx, panel,
+ &s6e8fco_m1906f9_panel_funcs,
+ DRM_MODE_CONNECTOR_DSI);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+
+ ret = devm_regulator_bulk_get_const(dev,
+ ARRAY_SIZE(s6e8fco_m1906f9_supplies),
+ s6e8fco_m1906f9_supplies,
+ &ctx->supplies);
+ if (ret < 0)
+ return ret;
+
+ ctx->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+ if (IS_ERR(ctx->reset_gpio))
+ return dev_err_probe(dev, PTR_ERR(ctx->reset_gpio),
+ "Failed to get reset-gpios\n");
+
+ ctx->dsi = dsi;
+ mipi_dsi_set_drvdata(dsi, ctx);
+
+ dsi->lanes = 4;
+ dsi->format = MIPI_DSI_FMT_RGB888;
+ dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
+ MIPI_DSI_CLOCK_NON_CONTINUOUS;
+
+ ctx->panel.prepare_prev_first = true;
+
+ ctx->panel.backlight = s6e8fco_m1906f9_create_backlight(dsi);
+ if (IS_ERR(ctx->panel.backlight))
+ return dev_err_probe(dev, PTR_ERR(ctx->panel.backlight),
+ "Failed to create backlight\n");
+
+ drm_panel_add(&ctx->panel);
+
+ ret = mipi_dsi_attach(dsi);
+ if (ret < 0) {
+ drm_panel_remove(&ctx->panel);
+ return dev_err_probe(dev, ret, "Failed to attach to DSI host\n");
+ }
+
+ return 0;
+}
+
+static void s6e8fco_remove(struct mipi_dsi_device *dsi)
+{
+ struct s6e8fco_ctx *ctx = mipi_dsi_get_drvdata(dsi);
+ int ret;
+
+ ret = mipi_dsi_detach(dsi);
+ if (ret < 0)
+ dev_err(&dsi->dev, "Failed to detach from DSI host: %d\n", ret);
+
+ drm_panel_remove(&ctx->panel);
+}
+
+static const struct of_device_id samsung_s6e8fco_m1906f9_of_match[] = {
+ { .compatible = "samsung,s6e8fco-m1906f9" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, samsung_s6e8fco_m1906f9_of_match);
+
+static struct mipi_dsi_driver s6e8fco_m1906f9_driver = {
+ .probe = s6e8fco_m1906f9_probe,
+ .remove = s6e8fco_remove,
+ .driver = {
+ .name = "panel-samsung-s6e8fco-m1906f9",
+ .of_match_table = samsung_s6e8fco_m1906f9_of_match,
+ },
+};
+module_mipi_dsi_driver(s6e8fco_m1906f9_driver);
+
+MODULE_AUTHOR("Kamil Gołda <kamil.golda@protonmail.com>");
+MODULE_DESCRIPTION("DRM driver for Samsung s6e8fco DSI controller");
+MODULE_LICENSE("GPL");

--
2.53.0