This initial part of the panel driver was mostly generated by the
"linux-mdss-dsi-panel-driver-generator" tool [1], reading downstream
Android kernel file "dsi_panel_S6E88A0_AMS427AP24_qhd_octa_video.dtsi" [2].

On top of the generic output of the tool, there were a couple of changes
applied:
- Added mipi_dsi_dcs_set_display_on() to function s6e88a0_ams427ap24_on(),
  otherwise the display does not show up.
- In functions s6e88a0_ams427ap24_on() and s6e88a0_ams427ap24_off()
  changed DSI commands to multi context and used "accum_err" returns.
- In functions s6e88a0_ams427ap24_on() and s6e88a0_ams427ap24_off() replaced
  msleep() by mipi_dsi_msleep().
- The function s6e88a0_ams427ap24_get_modes() was changed to make use of
  drm_connector_helper_get_modes_fixed(). This also required to include
  drm/drm_probe_helper.h.
- In function s6e88a0_ams427ap24_probe() registring the regulators was changed
  to devm_regulator_bulk_get_const(). This required to change supplies in struct
  s6e88a0_ams427ap24 to a pointer.
- Removed bool "prepared" from struct s6e88a0_ams427ap24 and instead used
  framework-provided "panel->prepared" in functions s6e88a0_ams427ap24_prepare()
  and s6e88a0_ams427ap24_unprepare().

[1] https://github.com/msm8916-mainline/linux-mdss-dsi-panel-driver-generator
[2] https://github.com/msm8916-mainline/linux-downstream/blob/GT-I9195I/drivers/video/msm/mdss/samsung/S6E88A0_AMS427AP24/dsi_panel_S6E88A0_AMS427AP24_qhd_octa_video.dtsi

Signed-off-by: Jakob Hauser <jahau@rocketmail.com>
---
Coulnd't read out RAW EDID, /sys/class/drm/card0-DSI-1/edid is empty.

Changes in v2:
 - Removed bool "prepared" from struct s6e88a0_ams427ap24 and instead used
   framework-provided "panel->prepared" in functions s6e88a0_ams427ap24_prepare()
   and s6e88a0_ams427ap24_unprepare(). Mentioned this in the commit message.
---
 drivers/gpu/drm/panel/Kconfig                 |   9 +
 drivers/gpu/drm/panel/Makefile                |   1 +
 .../panel/panel-samsung-s6e88a0-ams427ap24.c  | 260 ++++++++++++++++++
 3 files changed, 270 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index bce4cb64184a..f8adc38447fb 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -632,6 +632,15 @@ config DRM_PANEL_SAMSUNG_AMS639RQ08
 	  Say Y or M here if you want to enable support for the
 	  Samsung AMS639RQ08 FHD Plus (2340x1080@60Hz) CMD mode panel.
 
+config DRM_PANEL_SAMSUNG_S6E88A0_AMS427AP24
+	tristate "Samsung AMS427AP24 panel with S6E88A0 controller"
+	depends on GPIOLIB && OF && REGULATOR
+	depends on DRM_MIPI_DSI
+	help
+	  Say Y here if you want to enable support for Samsung AMS427AP24 panel
+	  with S6E88A0 controller (found in Samsung Galaxy S4 Mini Value Edition
+	  GT-I9195I). To compile this driver as a module, choose M here.
+
 config DRM_PANEL_SAMSUNG_S6E88A0_AMS452EF01
 	tristate "Samsung AMS452EF01 panel with S6E88A0 DSI video mode controller"
 	depends on OF
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index 4db02c2411ae..7dcf72646cac 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -77,6 +77,7 @@ obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63J0X03) += panel-samsung-s6e63j0x03.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63M0) += panel-samsung-s6e63m0.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63M0_SPI) += panel-samsung-s6e63m0-spi.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63M0_DSI) += panel-samsung-s6e63m0-dsi.o
+obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E88A0_AMS427AP24) += panel-samsung-s6e88a0-ams427ap24.o
 obj-$(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_SOFEF00) += panel-samsung-sofef00.o
diff --git a/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c b/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c
new file mode 100644
index 000000000000..0ab2768e0e2b
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Samsung AMS427AP24 panel with S6E88A0 controller
+ * Copyright (c) 2024 Jakob Hauser <jahau@rocketmail.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of.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 s6e88a0_ams427ap24 {
+	struct drm_panel panel;
+	struct mipi_dsi_device *dsi;
+	struct regulator_bulk_data *supplies;
+	struct gpio_desc *reset_gpio;
+};
+
+const struct regulator_bulk_data s6e88a0_ams427ap24_supplies[] = {
+	{ .supply = "vdd3" },
+	{ .supply = "vci" },
+};
+
+static inline
+struct s6e88a0_ams427ap24 *to_s6e88a0_ams427ap24(struct drm_panel *panel)
+{
+	return container_of(panel, struct s6e88a0_ams427ap24, panel);
+}
+
+static void s6e88a0_ams427ap24_reset(struct s6e88a0_ams427ap24 *ctx)
+{
+	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
+	usleep_range(5000, 6000);
+	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
+	usleep_range(1000, 2000);
+	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
+	usleep_range(18000, 19000);
+}
+
+static int s6e88a0_ams427ap24_on(struct s6e88a0_ams427ap24 *ctx)
+{
+	struct mipi_dsi_device *dsi = ctx->dsi;
+	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
+
+	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf0, 0x5a, 0x5a);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfc, 0x5a, 0x5a);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb0, 0x11);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfd, 0x11);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb0, 0x13);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfd, 0x18);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb0, 0x02);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb8, 0x30);
+
+	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx);
+	mipi_dsi_msleep(&dsi_ctx, 20);
+
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf1, 0x5a, 0x5a);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xcc, 0x4c);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf2, 0x03, 0x0d);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf1, 0xa5, 0xa5);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xca,
+				     0x01, 0x00, 0x01, 0x00, 0x01, 0x00, 0x80,
+				     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
+				     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
+				     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
+				     0x80, 0x80, 0x00, 0x00, 0x00);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb2,
+				     0x40, 0x08, 0x20, 0x00, 0x08);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb6, 0x28, 0x0b);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf7, 0x03);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x55, 0x00);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf0, 0xa5, 0xa5);
+	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfc, 0xa5, 0xa5);
+
+	mipi_dsi_dcs_set_display_on_multi(&dsi_ctx);
+
+	return dsi_ctx.accum_err;
+}
+
+static int s6e88a0_ams427ap24_off(struct s6e88a0_ams427ap24 *ctx)
+{
+	struct mipi_dsi_device *dsi = ctx->dsi;
+	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
+
+	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+	mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
+	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx);
+	mipi_dsi_msleep(&dsi_ctx, 120);
+
+	return dsi_ctx.accum_err;
+}
+
+static int s6e88a0_ams427ap24_prepare(struct drm_panel *panel)
+{
+	struct s6e88a0_ams427ap24 *ctx = to_s6e88a0_ams427ap24(panel);
+	struct device *dev = &ctx->dsi->dev;
+	int ret;
+
+	if (panel->prepared)
+		return 0;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(s6e88a0_ams427ap24_supplies),
+				    ctx->supplies);
+	if (ret < 0) {
+		dev_err(dev, "Failed to enable regulators: %d\n", ret);
+		return ret;
+	}
+
+	s6e88a0_ams427ap24_reset(ctx);
+
+	ret = s6e88a0_ams427ap24_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(s6e88a0_ams427ap24_supplies),
+				       ctx->supplies);
+		return ret;
+	}
+
+	panel->prepared = true;
+	return 0;
+}
+
+static int s6e88a0_ams427ap24_unprepare(struct drm_panel *panel)
+{
+	struct s6e88a0_ams427ap24 *ctx = to_s6e88a0_ams427ap24(panel);
+	struct device *dev = &ctx->dsi->dev;
+	int ret;
+
+	if (!panel->prepared)
+		return 0;
+
+	ret = s6e88a0_ams427ap24_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(s6e88a0_ams427ap24_supplies),
+			       ctx->supplies);
+
+	panel->prepared = false;
+	return 0;
+}
+
+static const struct drm_display_mode s6e88a0_ams427ap24_mode = {
+	.clock = (540 + 94 + 4 + 18) * (960 + 12 + 1 + 3) * 60 / 1000,
+	.hdisplay = 540,
+	.hsync_start = 540 + 94,
+	.hsync_end = 540 + 94 + 4,
+	.htotal = 540 + 94 + 4 + 18,
+	.vdisplay = 960,
+	.vsync_start = 960 + 12,
+	.vsync_end = 960 + 12 + 1,
+	.vtotal = 960 + 12 + 1 + 3,
+	.width_mm = 55,
+	.height_mm = 95,
+	.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
+};
+
+static int s6e88a0_ams427ap24_get_modes(struct drm_panel *panel,
+					struct drm_connector *connector)
+{
+	return drm_connector_helper_get_modes_fixed(connector,
+						    &s6e88a0_ams427ap24_mode);
+}
+
+static const struct drm_panel_funcs s6e88a0_ams427ap24_panel_funcs = {
+	.prepare = s6e88a0_ams427ap24_prepare,
+	.unprepare = s6e88a0_ams427ap24_unprepare,
+	.get_modes = s6e88a0_ams427ap24_get_modes,
+};
+
+static int s6e88a0_ams427ap24_probe(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct s6e88a0_ams427ap24 *ctx;
+	int ret;
+
+	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ret = devm_regulator_bulk_get_const(dev,
+				      ARRAY_SIZE(s6e88a0_ams427ap24_supplies),
+				      s6e88a0_ams427ap24_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 = 2;
+	dsi->format = MIPI_DSI_FMT_RGB888;
+	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
+			  MIPI_DSI_MODE_NO_EOT_PACKET;
+
+	drm_panel_init(&ctx->panel, dev, &s6e88a0_ams427ap24_panel_funcs,
+		       DRM_MODE_CONNECTOR_DSI);
+	ctx->panel.prepare_prev_first = true;
+
+	drm_panel_add(&ctx->panel);
+
+	ret = mipi_dsi_attach(dsi);
+	if (ret < 0) {
+		dev_err(dev, "Failed to attach to DSI host: %d\n", ret);
+		drm_panel_remove(&ctx->panel);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void s6e88a0_ams427ap24_remove(struct mipi_dsi_device *dsi)
+{
+	struct s6e88a0_ams427ap24 *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 s6e88a0_ams427ap24_of_match[] = {
+	{ .compatible = "samsung,s6e88a0-ams427ap24" },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, s6e88a0_ams427ap24_of_match);
+
+static struct mipi_dsi_driver s6e88a0_ams427ap24_driver = {
+	.probe = s6e88a0_ams427ap24_probe,
+	.remove = s6e88a0_ams427ap24_remove,
+	.driver = {
+		.name = "panel-s6e88a0-ams427ap24",
+		.of_match_table = s6e88a0_ams427ap24_of_match,
+	},
+};
+module_mipi_dsi_driver(s6e88a0_ams427ap24_driver);
+
+MODULE_AUTHOR("Jakob Hauser <jahau@rocketmail.com>");
+MODULE_DESCRIPTION("Samsung AMS427AP24 panel with S6E88A0 controller");
+MODULE_LICENSE("GPL v2");
-- 
2.39.5

Hi,

On 22/10/2024 23:33, Jakob Hauser wrote:
> This initial part of the panel driver was mostly generated by the
> "linux-mdss-dsi-panel-driver-generator" tool [1], reading downstream
> Android kernel file "dsi_panel_S6E88A0_AMS427AP24_qhd_octa_video.dtsi" [2].
> 
> On top of the generic output of the tool, there were a couple of changes
> applied:
> - Added mipi_dsi_dcs_set_display_on() to function s6e88a0_ams427ap24_on(),
>    otherwise the display does not show up.
> - In functions s6e88a0_ams427ap24_on() and s6e88a0_ams427ap24_off()
>    changed DSI commands to multi context and used "accum_err" returns.
> - In functions s6e88a0_ams427ap24_on() and s6e88a0_ams427ap24_off() replaced
>    msleep() by mipi_dsi_msleep().
> - The function s6e88a0_ams427ap24_get_modes() was changed to make use of
>    drm_connector_helper_get_modes_fixed(). This also required to include
>    drm/drm_probe_helper.h.
> - In function s6e88a0_ams427ap24_probe() registring the regulators was changed
>    to devm_regulator_bulk_get_const(). This required to change supplies in struct
>    s6e88a0_ams427ap24 to a pointer.
> - Removed bool "prepared" from struct s6e88a0_ams427ap24 and instead used
>    framework-provided "panel->prepared" in functions s6e88a0_ams427ap24_prepare()
>    and s6e88a0_ams427ap24_unprepare().
> 
> [1] https://github.com/msm8916-mainline/linux-mdss-dsi-panel-driver-generator
> [2] https://github.com/msm8916-mainline/linux-downstream/blob/GT-I9195I/drivers/video/msm/mdss/samsung/S6E88A0_AMS427AP24/dsi_panel_S6E88A0_AMS427AP24_qhd_octa_video.dtsi
> 
> Signed-off-by: Jakob Hauser <jahau@rocketmail.com>
> ---
> Coulnd't read out RAW EDID, /sys/class/drm/card0-DSI-1/edid is empty.

DSI panels doesn't have EDID, you can drop this comment

> 
> Changes in v2:
>   - Removed bool "prepared" from struct s6e88a0_ams427ap24 and instead used
>     framework-provided "panel->prepared" in functions s6e88a0_ams427ap24_prepare()
>     and s6e88a0_ams427ap24_unprepare(). Mentioned this in the commit message.
> ---
>   drivers/gpu/drm/panel/Kconfig                 |   9 +
>   drivers/gpu/drm/panel/Makefile                |   1 +
>   .../panel/panel-samsung-s6e88a0-ams427ap24.c  | 260 ++++++++++++++++++
>   3 files changed, 270 insertions(+)
>   create mode 100644 drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index bce4cb64184a..f8adc38447fb 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -632,6 +632,15 @@ config DRM_PANEL_SAMSUNG_AMS639RQ08
>   	  Say Y or M here if you want to enable support for the
>   	  Samsung AMS639RQ08 FHD Plus (2340x1080@60Hz) CMD mode panel.
>   
> +config DRM_PANEL_SAMSUNG_S6E88A0_AMS427AP24
> +	tristate "Samsung AMS427AP24 panel with S6E88A0 controller"
> +	depends on GPIOLIB && OF && REGULATOR
> +	depends on DRM_MIPI_DSI
> +	help
> +	  Say Y here if you want to enable support for Samsung AMS427AP24 panel
> +	  with S6E88A0 controller (found in Samsung Galaxy S4 Mini Value Edition
> +	  GT-I9195I). To compile this driver as a module, choose M here.
> +
>   config DRM_PANEL_SAMSUNG_S6E88A0_AMS452EF01
>   	tristate "Samsung AMS452EF01 panel with S6E88A0 DSI video mode controller"
>   	depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index 4db02c2411ae..7dcf72646cac 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -77,6 +77,7 @@ obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63J0X03) += panel-samsung-s6e63j0x03.o
>   obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63M0) += panel-samsung-s6e63m0.o
>   obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63M0_SPI) += panel-samsung-s6e63m0-spi.o
>   obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63M0_DSI) += panel-samsung-s6e63m0-dsi.o
> +obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E88A0_AMS427AP24) += panel-samsung-s6e88a0-ams427ap24.o
>   obj-$(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_SOFEF00) += panel-samsung-sofef00.o
> diff --git a/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c b/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c
> new file mode 100644
> index 000000000000..0ab2768e0e2b
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-samsung-s6e88a0-ams427ap24.c
> @@ -0,0 +1,260 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Samsung AMS427AP24 panel with S6E88A0 controller
> + * Copyright (c) 2024 Jakob Hauser <jahau@rocketmail.com>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/of.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 s6e88a0_ams427ap24 {
> +	struct drm_panel panel;
> +	struct mipi_dsi_device *dsi;
> +	struct regulator_bulk_data *supplies;
> +	struct gpio_desc *reset_gpio;
> +};
> +
> +const struct regulator_bulk_data s6e88a0_ams427ap24_supplies[] = {

Please add static

> +	{ .supply = "vdd3" },
> +	{ .supply = "vci" },
> +};
> +
> +static inline
> +struct s6e88a0_ams427ap24 *to_s6e88a0_ams427ap24(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct s6e88a0_ams427ap24, panel);
> +}
> +
> +static void s6e88a0_ams427ap24_reset(struct s6e88a0_ams427ap24 *ctx)
> +{
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
> +	usleep_range(5000, 6000);
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
> +	usleep_range(1000, 2000);
> +	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
> +	usleep_range(18000, 19000);
> +}
> +
> +static int s6e88a0_ams427ap24_on(struct s6e88a0_ams427ap24 *ctx)
> +{
> +	struct mipi_dsi_device *dsi = ctx->dsi;
> +	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
> +
> +	dsi->mode_flags |= MIPI_DSI_MODE_LPM;
> +
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf0, 0x5a, 0x5a);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfc, 0x5a, 0x5a);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb0, 0x11);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfd, 0x11);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb0, 0x13);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfd, 0x18);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb0, 0x02);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb8, 0x30);
> +
> +	mipi_dsi_dcs_exit_sleep_mode_multi(&dsi_ctx);
> +	mipi_dsi_msleep(&dsi_ctx, 20);
> +
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf1, 0x5a, 0x5a);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xcc, 0x4c);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf2, 0x03, 0x0d);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf1, 0xa5, 0xa5);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xca,
> +				     0x01, 0x00, 0x01, 0x00, 0x01, 0x00, 0x80,
> +				     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
> +				     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
> +				     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
> +				     0x80, 0x80, 0x00, 0x00, 0x00);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb2,
> +				     0x40, 0x08, 0x20, 0x00, 0x08);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xb6, 0x28, 0x0b);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf7, 0x03);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0x55, 0x00);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xf0, 0xa5, 0xa5);
> +	mipi_dsi_dcs_write_seq_multi(&dsi_ctx, 0xfc, 0xa5, 0xa5);
> +
> +	mipi_dsi_dcs_set_display_on_multi(&dsi_ctx);
> +
> +	return dsi_ctx.accum_err;
> +}
> +
> +static int s6e88a0_ams427ap24_off(struct s6e88a0_ams427ap24 *ctx)
> +{
> +	struct mipi_dsi_device *dsi = ctx->dsi;
> +	struct mipi_dsi_multi_context dsi_ctx = { .dsi = dsi };
> +
> +	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
> +
> +	mipi_dsi_dcs_set_display_off_multi(&dsi_ctx);
> +	mipi_dsi_dcs_enter_sleep_mode_multi(&dsi_ctx);
> +	mipi_dsi_msleep(&dsi_ctx, 120);
> +
> +	return dsi_ctx.accum_err;
> +}
> +
> +static int s6e88a0_ams427ap24_prepare(struct drm_panel *panel)
> +{
> +	struct s6e88a0_ams427ap24 *ctx = to_s6e88a0_ams427ap24(panel);
> +	struct device *dev = &ctx->dsi->dev;
> +	int ret;
> +
> +	if (panel->prepared)
> +		return 0;

You can drop these, _prepare won't be called twice, the framework controls that.

> +
> +	ret = regulator_bulk_enable(ARRAY_SIZE(s6e88a0_ams427ap24_supplies),
> +				    ctx->supplies);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to enable regulators: %d\n", ret);
> +		return ret;
> +	}
> +
> +	s6e88a0_ams427ap24_reset(ctx);
> +
> +	ret = s6e88a0_ams427ap24_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(s6e88a0_ams427ap24_supplies),
> +				       ctx->supplies);
> +		return ret;
> +	}
> +
> +	panel->prepared = true;

Ditto

> +	return 0;
> +}
> +
> +static int s6e88a0_ams427ap24_unprepare(struct drm_panel *panel)
> +{
> +	struct s6e88a0_ams427ap24 *ctx = to_s6e88a0_ams427ap24(panel);
> +	struct device *dev = &ctx->dsi->dev;
> +	int ret;
> +
> +	if (!panel->prepared)
> +		return 0;

Ditto

> +
> +	ret = s6e88a0_ams427ap24_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(s6e88a0_ams427ap24_supplies),
> +			       ctx->supplies);
> +
> +	panel->prepared = false;

Ditto

> +	return 0;
> +}
> +
> +static const struct drm_display_mode s6e88a0_ams427ap24_mode = {
> +	.clock = (540 + 94 + 4 + 18) * (960 + 12 + 1 + 3) * 60 / 1000,
> +	.hdisplay = 540,
> +	.hsync_start = 540 + 94,
> +	.hsync_end = 540 + 94 + 4,
> +	.htotal = 540 + 94 + 4 + 18,
> +	.vdisplay = 960,
> +	.vsync_start = 960 + 12,
> +	.vsync_end = 960 + 12 + 1,
> +	.vtotal = 960 + 12 + 1 + 3,
> +	.width_mm = 55,
> +	.height_mm = 95,
> +	.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
> +};
> +
> +static int s6e88a0_ams427ap24_get_modes(struct drm_panel *panel,
> +					struct drm_connector *connector)
> +{
> +	return drm_connector_helper_get_modes_fixed(connector,
> +						    &s6e88a0_ams427ap24_mode);
> +}
> +
> +static const struct drm_panel_funcs s6e88a0_ams427ap24_panel_funcs = {
> +	.prepare = s6e88a0_ams427ap24_prepare,
> +	.unprepare = s6e88a0_ams427ap24_unprepare,
> +	.get_modes = s6e88a0_ams427ap24_get_modes,
> +};
> +
> +static int s6e88a0_ams427ap24_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct s6e88a0_ams427ap24 *ctx;
> +	int ret;
> +
> +	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
> +	if (!ctx)
> +		return -ENOMEM;
> +
> +	ret = devm_regulator_bulk_get_const(dev,
> +				      ARRAY_SIZE(s6e88a0_ams427ap24_supplies),
> +				      s6e88a0_ams427ap24_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 = 2;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
> +			  MIPI_DSI_MODE_NO_EOT_PACKET;
> +
> +	drm_panel_init(&ctx->panel, dev, &s6e88a0_ams427ap24_panel_funcs,
> +		       DRM_MODE_CONNECTOR_DSI);
> +	ctx->panel.prepare_prev_first = true;
> +
> +	drm_panel_add(&ctx->panel);
> +
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to attach to DSI host: %d\n", ret);
> +		drm_panel_remove(&ctx->panel);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void s6e88a0_ams427ap24_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct s6e88a0_ams427ap24 *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 s6e88a0_ams427ap24_of_match[] = {
> +	{ .compatible = "samsung,s6e88a0-ams427ap24" },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, s6e88a0_ams427ap24_of_match);
> +
> +static struct mipi_dsi_driver s6e88a0_ams427ap24_driver = {
> +	.probe = s6e88a0_ams427ap24_probe,
> +	.remove = s6e88a0_ams427ap24_remove,
> +	.driver = {
> +		.name = "panel-s6e88a0-ams427ap24",
> +		.of_match_table = s6e88a0_ams427ap24_of_match,
> +	},
> +};
> +module_mipi_dsi_driver(s6e88a0_ams427ap24_driver);
> +
> +MODULE_AUTHOR("Jakob Hauser <jahau@rocketmail.com>");
> +MODULE_DESCRIPTION("Samsung AMS427AP24 panel with S6E88A0 controller");
> +MODULE_LICENSE("GPL v2");


Thanks,
Neil