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: adb9d5a2cc77 ("drm/dp: Move DisplayPort helpers into separate helper module") Fixes: 5f04e7ce392d ("drm/panel-edp: Split eDP panels out of panel-simple") Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx> 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 --- drivers/gpu/drm/panel/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig index 434c2861bb40..0aec5a10b064 100644 --- a/drivers/gpu/drm/panel/Kconfig +++ b/drivers/gpu/drm/panel/Kconfig @@ -106,6 +106,7 @@ 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 -- 2.34.1