When CONFIG_DRM_RCAR_DU=y and CONFIG_DRM_RCAR_MIPI_DSI=m, calls from the builtin driver to the mipi driver fail due to linker errors. Since the RCAR_MIPI_DSI driver is not always required, fix the build error by making DRM_RCAR_DU optionally depend on the RCAR_MIPI_DSI Kconfig symbol. This prevents the problematic kconfig combination without requiring that RCAR_MIPI_DSI always be enabled. aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_crtc.o: in function `rcar_du_crtc_atomic_enable': rcar_du_crtc.c:(.text+0x3a18): undefined reference to `rcar_mipi_dsi_pclk_enable' aarch64-linux-ld: drivers/gpu/drm/rcar-du/rcar_du_crtc.o: in function `rcar_du_crtc_atomic_disable': rcar_du_crtc.c:(.text+0x47cc): undefined reference to `rcar_mipi_dsi_pclk_disable' Fixes: 957fe62d7d15 ("drm: rcar-du: Fix DSI enable & disable sequence") Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Cc: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx> Cc: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> Cc: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx> Cc: LUU HOAI <hoai.luu.ub@xxxxxxxxxxx> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx Cc: linux-renesas-soc@xxxxxxxxxxxxxxx Cc: David Airlie <airlied@xxxxxxxxx> Cc: Daniel Vetter <daniel@xxxxxxxx> --- drivers/gpu/drm/rcar-du/Kconfig | 1 + 1 file changed, 1 insertion(+) diff -- a/drivers/gpu/drm/rcar-du/Kconfig b/drivers/gpu/drm/rcar-du/Kconfig --- a/drivers/gpu/drm/rcar-du/Kconfig +++ b/drivers/gpu/drm/rcar-du/Kconfig @@ -4,6 +4,7 @@ config DRM_RCAR_DU depends on DRM && OF depends on ARM || ARM64 depends on ARCH_RENESAS || COMPILE_TEST + depends on DRM_RCAR_MIPI_DSI || DRM_RCAR_MIPI_DSI=n select DRM_KMS_HELPER select DRM_GEM_DMA_HELPER select VIDEOMODE_HELPERS