The Lontium DRM bridge drivers use mipi_dsi_() function interfaces so they need to select DRM_MIPI_DSI to prevent build errors. ERROR: modpost: "mipi_dsi_attach" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined! ERROR: modpost: "mipi_dsi_device_register_full" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined! ERROR: modpost: "of_find_mipi_dsi_host_by_node" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined! ERROR: modpost: "mipi_dsi_device_unregister" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined! ERROR: modpost: "mipi_dsi_detach" [drivers/gpu/drm/bridge/lontium-lt9611uxc.ko] undefined! ERROR: modpost: "mipi_dsi_attach" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined! ERROR: modpost: "mipi_dsi_device_register_full" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined! ERROR: modpost: "of_find_mipi_dsi_host_by_node" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined! ERROR: modpost: "mipi_dsi_device_unregister" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined! ERROR: modpost: "mipi_dsi_detach" [drivers/gpu/drm/bridge/lontium-lt9611.ko] undefined! WARNING: modpost: suppressed 5 unresolved symbol warnings because there were too many) Fixes: 23278bf54afe ("drm/bridge: Introduce LT9611 DSI to HDMI bridge") Fixes: 0cbbd5b1a012 ("drm: bridge: add support for lontium LT9611UXC bridge") Fixes: 30e2ae943c26 ("drm/bridge: Introduce LT8912B DSI to HDMI bridge") Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Reported-by: kernel test robot <lkp@xxxxxxxxx> Cc: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> Cc: Sam Ravnborg <sam@xxxxxxxxxxxx> Cc: Vinod Koul <vkoul@xxxxxxxxxx> Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> Cc: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx> Cc: Adrien Grassein <adrien.grassein@xxxxxxxxx> Cc: Andrzej Hajda <a.hajda@xxxxxxxxxxx> Cc: Neil Armstrong <narmstrong@xxxxxxxxxxxx> Cc: Robert Foss <robert.foss@xxxxxxxxxx> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx --- drivers/gpu/drm/bridge/Kconfig | 3 +++ 1 file changed, 3 insertions(+) --- linux-next-20210414.orig/drivers/gpu/drm/bridge/Kconfig +++ linux-next-20210414/drivers/gpu/drm/bridge/Kconfig @@ -66,6 +66,7 @@ config DRM_LONTIUM_LT8912B depends on OF select DRM_PANEL_BRIDGE select DRM_KMS_HELPER + select DRM_MIPI_DSI select REGMAP_I2C help Driver for Lontium LT8912B DSI to HDMI bridge @@ -81,6 +82,7 @@ config DRM_LONTIUM_LT9611 depends on OF select DRM_PANEL_BRIDGE select DRM_KMS_HELPER + select DRM_MIPI_DSI select REGMAP_I2C help Driver for Lontium LT9611 DSI to HDMI bridge @@ -94,6 +96,7 @@ config DRM_LONTIUM_LT9611UXC depends on OF select DRM_PANEL_BRIDGE select DRM_KMS_HELPER + select DRM_MIPI_DSI select REGMAP_I2C help Driver for Lontium LT9611UXC DSI to HDMI bridge