drm/panel: Add driver for the Sony ACX565AKM panel

This panel is used on the Nokia N900.

The code is based on the omapdrm-specific panel-sony-acx565akm driver.
The hardware-related logic has been changed as little as possible to
avoid regressions as hardware availability is lacking to test the
changes. Follow-up patches should address the items listed in the TODO
list.

v2:
- fix checkpatch warning (lcd == NULL) => (!lcd) (sam)
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813201101.30980-8-laurent.pinchart@ideasonboard.com

drivers/gpu/drm/panel/Kconfig

@@ -316,6 +316,14 @@ config DRM_PANEL_SITRONIX_ST7789V
 	  Say Y here if you want to enable support for the Sitronix
 	  ST7789V controller for 240x320 LCD panels
 
+config DRM_PANEL_SONY_ACX565AKM
+	tristate "Sony ACX565AKM panel"
+	depends on GPIOLIB && OF && SPI
+	depends on BACKLIGHT_CLASS_DEVICE
+	help
+	  Say Y here if you want to enable support for the Sony ACX565AKM
+	  800x600 3.5" panel (found on the Nokia N900).
+
 config DRM_PANEL_TPO_TPG110
 	tristate "TPO TPG 800x400 panel"
 	depends on OF && SPI && GPIOLIB

drivers/gpu/drm/panel/Makefile

@@ -33,5 +33,6 @@ obj-$(CONFIG_DRM_PANEL_SHARP_LS037V7DW01) += panel-sharp-ls037v7dw01.o
 obj-$(CONFIG_DRM_PANEL_SHARP_LS043T1LE01) += panel-sharp-ls043t1le01.o
 obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7701) += panel-sitronix-st7701.o
 obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7789V) += panel-sitronix-st7789v.o
+obj-$(CONFIG_DRM_PANEL_SONY_ACX565AKM) += panel-sony-acx565akm.o
 obj-$(CONFIG_DRM_PANEL_TPO_TPG110) += panel-tpo-tpg110.o
 obj-$(CONFIG_DRM_PANEL_TRULY_NT35597_WQXGA) += panel-truly-nt35597.o

drivers/gpu/drm/panel/panel-sharp-ls037v7dw01.c

@@ -140,7 +140,7 @@ static int ls037v7dw01_probe(struct platform_device *pdev)
 	struct ls037v7dw01_panel *lcd;
 
 	lcd = devm_kzalloc(&pdev->dev, sizeof(*lcd), GFP_KERNEL);
-	if (lcd == NULL)
+	if (!lcd)
 		return -ENOMEM;
 
 	platform_set_drvdata(pdev, lcd);