From: Thomas Zimmermann <tzimmermann@xxxxxxx> commit 3755d35ee1d2454b20b8a1e20d790e56201678a4 upstream. As reported in [1], DRM_PANEL_EDP depends on DRM_DP_HELPER. Select the option to fix the build failure. The error message is shown below. arm-linux-gnueabihf-ld: drivers/gpu/drm/panel/panel-edp.o: in function `panel_edp_probe': panel-edp.c:(.text+0xb74): undefined reference to `drm_panel_dp_aux_backlight' make[1]: *** [/builds/linux/Makefile:1222: vmlinux] Error 1 The issue has been reported before, when DisplayPort helpers were hidden behind the option CONFIG_DRM_KMS_HELPER. [2] v2: * fix and expand commit description (Arnd) Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> Fixes: 9d6366e743f3 ("drm: fb_helper: improve CONFIG_FB dependency") Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx> Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx> Acked-by: Sam Ravnborg <sam@xxxxxxxxxxxx> Link: https://lore.kernel.org/dri-devel/CA+G9fYvN0NyaVkRQmA1O6rX7H8PPaZrUAD7=RDy33QY9rUU-9g@xxxxxxxxxxxxxx/ # [1] Link: https://lore.kernel.org/all/20211117062704.14671-1-rdunlap@xxxxxxxxxxxxx/ # [2] Cc: Thomas Zimmermann <tzimmermann@xxxxxxx> Cc: Lyude Paul <lyude@xxxxxxxxxx> Cc: Daniel Vetter <daniel@xxxxxxxx> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> Cc: Maxime Ripard <mripard@xxxxxxxxxx> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx Link: https://patchwork.freedesktop.org/patch/msgid/20220203093922.20754-1-tzimmermann@xxxxxxx Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/panel/Kconfig | 1 + 1 file changed, 1 insertion(+) --- a/drivers/gpu/drm/panel/Kconfig +++ b/drivers/gpu/drm/panel/Kconfig @@ -95,6 +95,7 @@ config DRM_PANEL_EDP depends on PM select VIDEOMODE_HELPERS select DRM_DP_AUX_BUS + select DRM_DP_HELPER help DRM panel driver for dumb eDP panels that need at most a regulator and a GPIO to be powered up. Optionally a backlight can be attached so