From 65f0dd566ef33ab029cc4b2d35ab37ed97e0c99a Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Thu, 28 Apr 2022 10:22:44 +0200
Subject: drm/display: Select DP helper for DRM_DP_AUX_CHARDEV and DRM_DP_CEC
Git-commit: b2aa405e89a4025642ba53897bb7b9ef5de210a9
Patch-mainline: v5.19-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
The DRM_DP_AUX_CHARDEV and DRM_DP_CEC Kconfig symbols enable code that use
DP helper functions, that are only present if CONFIG_DRM_DISPLAY_DP_HELPER
is also enabled.
But these don't select the DRM_DISPLAY_DP_HELPER symbol, meaning that it
is possible to enable any of them without CONFIG_DRM_DISPLAY_DP_HELPER.
That will lead to the following linking errors with the mentioned config:
LD vmlinux.o
MODPOST vmlinux.symvers
MODINFO modules.builtin.modinfo
GEN modules.builtin
LD .tmp_vmlinux.kallsyms1
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.S
LD .tmp_vmlinux.kallsyms2
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.S
LD vmlinux
SYSMAP System.map
SORTTAB vmlinux
OBJCOPY arch/arm64/boot/Image
MODPOST modules-only.symvers
ERROR: modpost: "drm_dp_dpcd_write" [drivers/gpu/drm/display/drm_display_helper.ko] undefined!
ERROR: modpost: "drm_dp_read_desc" [drivers/gpu/drm/display/drm_display_helper.ko] undefined!
ERROR: modpost: "drm_dp_dpcd_read" [drivers/gpu/drm/display/drm_display_helper.ko] undefined!
make[1]: *** [scripts/Makefile.modpost:134: modules-only.symvers] Error 1
make[1]: *** Deleting file 'modules-only.symvers'
make: *** [Makefile:1749: modules] Error 2
Besides making these symbols to select CONFIG_DRM_DISPLAY_DP_HELPER, make
them to depend on DRM_DISPLAY_HELPER, since can't be enabled without it.
Note: It seems this has been an issue for a long time but was made easier
to reproduce after the commit 1e0f66420b13 ("drm/display: Introduce a DRM
display-helper module"). Adding a Fixes: tag just to make sure that this
fix will be picked for stable once the mentioned change also lands there.
Fixes: 1e0f66420b13 ("drm/display: Introduce a DRM display-helper module")
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220428082244.390859-1-javierm@redhat.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/display/Kconfig | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
index f84f1b0cd23f..1b6e6af37546 100644
--- a/drivers/gpu/drm/display/Kconfig
+++ b/drivers/gpu/drm/display/Kconfig
@@ -31,7 +31,8 @@ config DRM_DISPLAY_HDMI_HELPER
config DRM_DP_AUX_CHARDEV
bool "DRM DP AUX Interface"
- depends on DRM
+ depends on DRM && DRM_DISPLAY_HELPER
+ select DRM_DISPLAY_DP_HELPER
help
Choose this option to enable a /dev/drm_dp_auxN node that allows to
read and write values to arbitrary DPCD registers on the DP aux
@@ -39,7 +40,8 @@ config DRM_DP_AUX_CHARDEV
config DRM_DP_CEC
bool "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support"
- depends on DRM
+ depends on DRM && DRM_DISPLAY_HELPER
+ select DRM_DISPLAY_DP_HELPER
select CEC_CORE
help
Choose this option if you want to enable HDMI CEC support for
--
2.38.1