regression: Build failure of mainline kernel with qcom_defconfig

From: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	Javier Martinez Canillas <javierm@redhat.com>,
	Jani Nikula <jani.nikula@intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org
Subject: regression: Build failure of mainline kernel with qcom_defconfig
Date: Sat, 26 Feb 2022 12:39:18 +0000	[thread overview]
Message-ID: <YhofdlzadzRmy7tj@debian> (raw)

Hi Arnd, All,

We recently noticed that arm "qcom_defconfig" failed to build with the error:

arm-linux-gnueabi-ld: drivers/gpu/drm/panel/panel-edp.o: in function `panel_edp_probe':
drivers/gpu/drm/panel/panel-edp.c:843: undefined reference to `drm_panel_dp_aux_backlight'

I have done a bisect and it points to:
9d6366e743f3 ("drm: fb_helper: improve CONFIG_FB dependency")

Here is the complete bisect log:

# bad: [df0cc57e057f18e44dac8e6c18aba47ab53202f9] Linux 5.16
# good: [8bb7eca972ad531c9b149c0a51ab43a417385813] Linux 5.15
git bisect start 'v5.16' 'v5.15'
# good: [2219b0ceefe835b92a8a74a73fe964aa052742a2] Merge tag 'soc-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
git bisect good 2219b0ceefe835b92a8a74a73fe964aa052742a2
# good: [206825f50f908771934e1fba2bfc2e1f1138b36a] Merge tag 'mtd/for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux
git bisect good 206825f50f908771934e1fba2bfc2e1f1138b36a
# bad: [4e1fddc98d2585ddd4792b5e44433dcee7ece001] tcp_cubic: fix spurious Hystart ACK train detections for not-cwnd-limited flows
git bisect bad 4e1fddc98d2585ddd4792b5e44433dcee7ece001
# good: [dbf49896187fd58c577fa1574a338e4f3672b4b2] Merge branch 'akpm' (patches from Andrew)
git bisect good dbf49896187fd58c577fa1574a338e4f3672b4b2
# bad: [0ecca62beb12eeb13965ed602905c8bf53ac93d0] Merge tag 'ceph-for-5.16-rc1' of git://github.com/ceph/ceph-client
git bisect bad 0ecca62beb12eeb13965ed602905c8bf53ac93d0
# bad: [304ac8032d3fa2d37750969cd4b8d5736a1829d9] Merge tag 'drm-next-2021-11-12' of git://anongit.freedesktop.org/drm/drm
git bisect bad 304ac8032d3fa2d37750969cd4b8d5736a1829d9
# good: [f78e9de80f5ad15719a069a4e6c11e2777122188] Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
git bisect good f78e9de80f5ad15719a069a4e6c11e2777122188
# good: [806acd381960008700c15c3dc616d578e9558853] Merge tag 'amd-drm-fixes-5.16-2021-11-03' of https://gitlab.freedesktop.org/agd5f/linux into drm-next
git bisect good 806acd381960008700c15c3dc616d578e9558853
# bad: [f8ca7b74192b2e64bdfb89fb63c1d33b92bc899d] Merge tag 'drm-misc-next-fixes-2021-11-10' of git://anongit.freedesktop.org/drm/drm-misc into drm-next
git bisect bad f8ca7b74192b2e64bdfb89fb63c1d33b92bc899d
# good: [cecbc0c7eba7983965cac94f88d2db00b913253b] drm/i915/hdmi: Turn DP++ TMDS output buffers back on in encoder->shutdown()
git bisect good cecbc0c7eba7983965cac94f88d2db00b913253b
# bad: [14d9a37c952588930d7226953359fea3ab956d39] Revert "drm/imx: Annotate dma-fence critical section in commit path"
git bisect bad 14d9a37c952588930d7226953359fea3ab956d39
# good: [5591c8f79db1729d9c5ac7f5b4d3a5c26e262d93] drm/udl: fix control-message timeout
git bisect good 5591c8f79db1729d9c5ac7f5b4d3a5c26e262d93
# bad: [9d6366e743f37d36ef69347924ead7bcc596076e] drm: fb_helper: improve CONFIG_FB dependency
git bisect bad 9d6366e743f37d36ef69347924ead7bcc596076e
# good: [e0e6d1ea18c804de51b47fa65092c4cf2000604c] MAINTAINERS: dri-devel is for all of drivers/gpu
git bisect good e0e6d1ea18c804de51b47fa65092c4cf2000604c
# first bad commit: [9d6366e743f37d36ef69347924ead7bcc596076e] drm: fb_helper: improve CONFIG_FB dependency

And, indeed reverting "9d6366e743f37d36ef69347924ead7bcc596076e" on top of
9137eda53752 ("Merge tag 'configfs-5.17-2022-02-25' of git://git.infradead.org/users/hch/configfs")
fixes the build.

I will be happy to test any patch fxing this issue.

--
Regards
Sudip