[PATCH] tinydrm: add backlight dependency

[Arnd Bergmann]

Calling devm_of_find_backlight directly means we get a link failure
without CONFIG_BACKLIGHT_CLASS_DEVICE:

drivers/gpu/drm/tinydrm/mi0283qt.o: In function `mi0283qt_probe':
mi0283qt.c:(.text+0x684): undefined reference to `devm_of_find_backlight'

This adds an explicit Kconfig dependency for it. While I did not
observe that failure for st7735r, I assume the same change is needed
there for the same reason.

Fixes: d1a2e7004b5e ("drm/tinydrm: Replace tinydrm_of_find_backlight with of_find_backlight")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 drivers/gpu/drm/tinydrm/Kconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/tinydrm/Kconfig b/drivers/gpu/drm/tinydrm/Kconfig
index 13339be843bc..4592a5e3f20b 100644
--- a/drivers/gpu/drm/tinydrm/Kconfig
+++ b/drivers/gpu/drm/tinydrm/Kconfig
@@ -23,6 +23,7 @@ config TINYDRM_ILI9225
 config TINYDRM_MI0283QT
 	tristate "DRM support for MI0283QT"
 	depends on DRM_TINYDRM && SPI
+	depends on BACKLIGHT_CLASS_DEVICE
 	select TINYDRM_MIPI_DBI
 	help
 	  DRM driver for the Multi-Inno MI0283QT display panel
@@ -54,6 +55,7 @@ config TINYDRM_ST7586
 config TINYDRM_ST7735R
 	tristate "DRM support for Sitronix ST7735R display panels"
 	depends on DRM_TINYDRM && SPI
+	depends on BACKLIGHT_CLASS_DEVICE
 	select TINYDRM_MIPI_DBI
 	help
 	  DRM driver Sitronix ST7735R with one of the following LCDs:
-- 
2.9.0