drm/panel: Add Himax HX83121A panel driver

Add a driver for panels using the Himax HX83121A Display Driver IC,
including support for the BOE/CSOT PPC357DB1-4, found in HUAWEI
Matebook E Go series (Gaokun2/3).

Signed-off-by: Pengyu Luo <mitltlatltl@gmail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20260316084040.728106-3-mitltlatltl@gmail.com

Author: right-0903

drivers/gpu/drm/panel/Kconfig

@@ -203,6 +203,17 @@ config DRM_PANEL_HIMAX_HX83112B
 	  Say Y here if you want to enable support for Himax HX83112B-based
 	  display panels, such as the one found in the Fairphone 3 smartphone.
 
+config DRM_PANEL_HIMAX_HX83121A
+	tristate "Himax HX83121A-based DSI panel"
+	depends on OF
+	depends on DRM_MIPI_DSI
+	depends on BACKLIGHT_CLASS_DEVICE
+	select DRM_KMS_HELPER
+	help
+	  Say Y here if you want to enable support for Himax HX83121A-based
+	  display panels, such as the one found in the HUAWEI Matebook E Go
+          series.
+
 config DRM_PANEL_HIMAX_HX8394
 	tristate "HIMAX HX8394 MIPI-DSI LCD panels"
 	depends on OF

drivers/gpu/drm/panel/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_DRM_PANEL_HIMAX_HX8279) += panel-himax-hx8279.o
 obj-$(CONFIG_DRM_PANEL_HIMAX_HX83102) += panel-himax-hx83102.o
 obj-$(CONFIG_DRM_PANEL_HIMAX_HX83112A) += panel-himax-hx83112a.o
 obj-$(CONFIG_DRM_PANEL_HIMAX_HX83112B) += panel-himax-hx83112b.o
+obj-$(CONFIG_DRM_PANEL_HIMAX_HX83121A) += panel-himax-hx83121a.o
 obj-$(CONFIG_DRM_PANEL_HIMAX_HX8394) += panel-himax-hx8394.o
 obj-$(CONFIG_DRM_PANEL_HYDIS_HV101HD1) += panel-hydis-hv101hd1.o
 obj-$(CONFIG_DRM_PANEL_ILITEK_IL9322) += panel-ilitek-ili9322.o