drm/panel: Add driver for Novatek NT35510-based panels

This adds a driver for panels based on the Novatek NT35510
display driver IC, such as the Hydis HVA40WV1 panel found
in the Samsung GT-S7710.

The NT35510 can be used with both internal and external
backlight (such as GPIO backlight) so we support both:
if no external backlight is found, we register a subdriver
for the internal backlight.

Cc: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200223121841.26836-3-linus.walleij@linaro.org

MAINTAINERS

@@ -5335,6 +5335,13 @@ F:	drivers/gpu/drm/msm/
 F:	include/uapi/drm/msm_drm.h
 F:	Documentation/devicetree/bindings/display/msm/
 
+DRM DRIVER FOR NOVATEK NT35510 PANELS
+M:	Linus Walleij <linus.walleij@linaro.org>
+T:	git git://anongit.freedesktop.org/drm/drm-misc
+S:	Maintained
+F:	drivers/gpu/drm/panel/panel-novatek-nt35510.c
+F:	Documentation/devicetree/bindings/display/panel/novatek,nt35510.yaml
+
 DRM DRIVER FOR NVIDIA GEFORCE/QUADRO GPUS
 M:	Ben Skeggs <bskeggs@redhat.com>
 L:	dri-devel@lists.freedesktop.org

drivers/gpu/drm/panel/Kconfig

@@ -167,6 +167,16 @@ config DRM_PANEL_NEC_NL8048HL11
 	  panel (found on the Zoom2/3/3630 SDP boards). To compile this driver
 	  as a module, choose M here.
 
+config DRM_PANEL_NOVATEK_NT35510
+	tristate "Novatek NT35510 RGB 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 panels built
+	  around the Novatek NT35510 display controller, such as some
+	  Hydis panels.
+
 config DRM_PANEL_NOVATEK_NT39016
 	tristate "Novatek NT39016 RGB/SPI panel"
 	depends on OF && SPI

drivers/gpu/drm/panel/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK500HD1829) += panel-leadtek-ltk500hd1829.o
 obj-$(CONFIG_DRM_PANEL_LG_LB035Q02) += panel-lg-lb035q02.o
 obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
 obj-$(CONFIG_DRM_PANEL_NEC_NL8048HL11) += panel-nec-nl8048hl11.o
+obj-$(CONFIG_DRM_PANEL_NOVATEK_NT35510) += panel-novatek-nt35510.o
 obj-$(CONFIG_DRM_PANEL_NOVATEK_NT39016) += panel-novatek-nt39016.o
 obj-$(CONFIG_DRM_PANEL_OLIMEX_LCD_OLINUXINO) += panel-olimex-lcd-olinuxino.o
 obj-$(CONFIG_DRM_PANEL_ORISETECH_OTM8009A) += panel-orisetech-otm8009a.o