drm/tinydrm: Replace tinydrm_of_find_backlight with of_find_backlight

Remove tinydrm_of_find_backlight from tinydrm-helpers.c. We now have
a generic of_find_backlight defined in backlight.c. Let the callers
of tinydrm_of_find_backlight call of_find_backlight. Also, remove
select BACKLIGHT_LCD_SUPPORT and select BACKLIGHT_CLASS_DEVICE from
tinydrm/Kconfig as it is a hack that is no longer needed.

Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/11dd1cabd098a730d07ab04c5987b139d14d8b21.1516810725.git.meghana.madhyastha@gmail.com

drivers/gpu/drm/tinydrm/Kconfig

@@ -3,8 +3,6 @@ menuconfig DRM_TINYDRM
 	depends on DRM
 	select DRM_KMS_HELPER
 	select DRM_KMS_CMA_HELPER
-	select BACKLIGHT_LCD_SUPPORT
-	select BACKLIGHT_CLASS_DEVICE
 	help
 	  Choose this option if you have a tinydrm supported display.
 	  If M is selected the module will be called tinydrm.

drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c

@@ -236,46 +236,6 @@ void tinydrm_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 }
 EXPORT_SYMBOL(tinydrm_xrgb8888_to_gray8);
 
-/**
- * tinydrm_of_find_backlight - Find backlight device in device-tree
- * @dev: Device
- *
- * This function looks for a DT node pointed to by a property named 'backlight'
- * and uses of_find_backlight_by_node() to get the backlight device.
- * Additionally if the brightness property is zero, it is set to
- * max_brightness.
- *
- * Returns:
- * NULL if there's no backlight property.
- * Error pointer -EPROBE_DEFER if the DT node is found, but no backlight device
- * is found.
- * If the backlight device is found, a pointer to the structure is returned.
- */
-struct backlight_device *tinydrm_of_find_backlight(struct device *dev)
-{
-	struct backlight_device *backlight;
-	struct device_node *np;
-
-	np = of_parse_phandle(dev->of_node, "backlight", 0);
-	if (!np)
-		return NULL;
-
-	backlight = of_find_backlight_by_node(np);
-	of_node_put(np);
-
-	if (!backlight)
-		return ERR_PTR(-EPROBE_DEFER);
-
-	if (!backlight->props.brightness) {
-		backlight->props.brightness = backlight->props.max_brightness;
-		DRM_DEBUG_KMS("Backlight brightness set to %d\n",
-			      backlight->props.brightness);
-	}
-
-	return backlight;
-}
-EXPORT_SYMBOL(tinydrm_of_find_backlight);
-
 #if IS_ENABLED(CONFIG_SPI)
 
 /**

drivers/gpu/drm/tinydrm/mi0283qt.c

@@ -9,6 +9,7 @@
  * (at your option) any later version.
  */
 
+#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>
@@ -195,7 +196,7 @@ static int mi0283qt_probe(struct spi_device *spi)
 	if (IS_ERR(mipi->regulator))
 		return PTR_ERR(mipi->regulator);
 
-	mipi->backlight = tinydrm_of_find_backlight(dev);
+	mipi->backlight = of_find_backlight(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 

drivers/gpu/drm/tinydrm/st7735r.c

@@ -5,6 +5,7 @@
  * Copyright 2017 David Lechner <david@lechnology.com>
  */
 
+#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/dma-buf.h>
 #include <linux/gpio/consumer.h>
@@ -163,7 +164,7 @@ static int st7735r_probe(struct spi_device *spi)
 		return PTR_ERR(dc);
 	}
 
-	mipi->backlight = tinydrm_of_find_backlight(dev);
+	mipi->backlight = of_find_backlight(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 

include/drm/tinydrm/tinydrm-helpers.h

@@ -46,8 +46,6 @@ void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
 void tinydrm_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 			       struct drm_clip_rect *clip);
 
-struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
-
 size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len);
 bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw);
 int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,