Re: [PATCH 5.15 808/917] drm: fb_helper: improve CONFIG_FB dependency

[Alan J. Wylie]

Arnd Bergmann <arnd@xxxxxxxx> writes:

> Ah right, I ran into a similar thing on my randconfig builds, this is
> what I have
> applied locally but wasn't completely sure about yet, it may need additional
> 'select DRM_KMS_CMA_HELPER' to cover all instances:

With 5.15.3, I had these errors on *one* of my boxes with Nvidia
drivers when building the nvidia drivers

Gentoo, nvidia-drivers-470.86

ERROR: modpost: "drm_atomic_helper_update_plane" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
ERROR: modpost: "drm_atomic_helper_connector_reset" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
ERROR: modpost: "drm_atomic_helper_page_flip" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
ERROR: modpost: "drm_atomic_helper_swap_state" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
ERROR: modpost: "drm_helper_probe_single_connector_modes" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
ERROR: modpost: "drm_kms_helper_hotplug_event" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
ERROR: modpost: "__drm_atomic_helper_crtc_destroy_state" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
ERROR: modpost: "drm_atomic_helper_crtc_reset" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
ERROR: modpost: "__drm_atomic_helper_plane_duplicate_state" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
ERROR: modpost: "drm_atomic_helper_connector_duplicate_state" [/work/tmp/portage/x11-drivers/nvidia-drivers-470.86/work/kernel/nvidia-drm.ko] undefined!
WARNING: modpost: suppressed 12 unresolved symbol warnings because there were too many) 

After "make oldconfig", many DRM settings have been lost. Enabling
"CONFIG_DRM_CIRRUS_QEMU" gets them back, though a better way should
be found.

$ uname -a
Linux bilbo 5.15.2 #3 SMP PREEMPT Fri Nov 12 14:41:08 GMT 2021 x86_64
AMD FX(tm)-4300 Quad-Core Processor AuthenticAMD GNU/Linux

$ zcat /proc/config.gz  > .config

$ grep CONFIG_DRM .config | grep -v "is not set$"
CONFIG_DRM=m
CONFIG_DRM_KMS_HELPER=m
CONFIG_DRM_FBDEV_EMULATION=y
CONFIG_DRM_FBDEV_OVERALLOC=100
CONFIG_DRM_I2C_CH7006=m
CONFIG_DRM_I2C_SIL164=m
CONFIG_DRM_PANEL=y
CONFIG_DRM_BRIDGE=y
CONFIG_DRM_PANEL_BRIDGE=y
CONFIG_DRM_PANEL_ORIENTATION_QUIRKS=m

$ make oldconfig
#
# configuration written to .config
#

$ grep CONFIG_DRM .config | grep -v "is not set$"
CONFIG_DRM=m
CONFIG_DRM_BRIDGE=y
CONFIG_DRM_PANEL_ORIENTATION_QUIRKS=m

Comparing with the working system, that has VMM installed, and hence

CONFIG_DRM_CIRRUS_QEMU=m

Setting this and things are working again.

$ zcat /proc/config.gz  > .config

$ ./scripts/config --enable CONFIG_DRM_CIRRUS_QEMU

$ make oldconfig
#
# configuration written to .config
#

$ grep CONFIG_DRM .config | grep -v "is not set$"
CONFIG_DRM=m
CONFIG_DRM_KMS_HELPER=m
CONFIG_DRM_FBDEV_EMULATION=y
CONFIG_DRM_FBDEV_OVERALLOC=100
CONFIG_DRM_GEM_SHMEM_HELPER=y
CONFIG_DRM_I2C_CH7006=m
CONFIG_DRM_I2C_SIL164=m
CONFIG_DRM_PANEL=y
CONFIG_DRM_BRIDGE=y
CONFIG_DRM_PANEL_BRIDGE=y
CONFIG_DRM_CIRRUS_QEMU=m
CONFIG_DRM_PANEL_ORIENTATION_QUIRKS=m
$

-- 
Alan J. Wylie                                          https://www.wylie.me.uk/

Dance like no-one's watching. / Encrypt like everyone is.
Security is inversely proportional to convenience