b2aa405e89
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
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.