Comment 19 for bug 1925211

commit 8cc0dcfdc1c0e0be107d0288f9c0cf1f4201be62
Author: Vineeth Vijayan <email address hidden>
Date: Fri Nov 20 09:36:38 2020 +0100

    s390/cio: remove pm support from ccw bus driver

    As part of removing broken pm-support from s390 arch, remove
    the pm callbacks from ccw-bus driver.The power-management functions
    are unused since the 'commit 394216275c7d ("s390: remove broken
    hibernate / power management support")'.

    Signed-off-by: Vineeth Vijayan <email address hidden>
    Reviewed-by: Peter Oberparleiter <email address hidden>
    Signed-off-by: Heiko Carstens <email address hidden>

 arch/s390/include/asm/ccwdev.h | 10 --
 drivers/s390/cio/cmf.c | 5 -
 drivers/s390/cio/device.c | 247 +----------------------------------------
 drivers/s390/cio/device.h | 1 -
 drivers/s390/cio/device_fsm.c | 6 -
 drivers/s390/cio/io_sch.h | 1 -

It seems it wasn't as unused/broken as they thought :-/
BTW the referenced 394216275c7d ("s390: remove broken hibernate / power management support") was in v5.7

Found by:

$ git bisect log
git bisect start
# good: [2c85ebc57b3e1817b6ce1a6b703928e113a90442] Linux 5.10
git bisect good 2c85ebc57b3e1817b6ce1a6b703928e113a90442
# bad: [f40ddce88593482919761f74910f42f4b84c004b] Linux 5.11
git bisect bad f40ddce88593482919761f74910f42f4b84c004b
# bad: [538fcf57aaee6ad78a05f52b69a99baa22b33418] Merge branches 'acpi-scan', 'acpi-pnp' and 'acpi-sleep'
git bisect bad 538fcf57aaee6ad78a05f52b69a99baa22b33418
# bad: [15b447361794271f4d03c04d82276a841fe06328] mm/lru: revise the comments of lru_lock
git bisect bad 15b447361794271f4d03c04d82276a841fe06328
# good: [b10733527bfd864605c33ab2e9a886eec317ec39] Merge tag 'amd-drm-next-5.11-2020-12-09' of git://people.freedesktop.org/~agd5f/linux into drm-next
git bisect good b10733527bfd864605c33ab2e9a886eec317ec39
# good: [2c075f38a708c578a752b738a45e8c26923eac2e] Merge branch 'radeon-fixes' (Radeon and amdgpu fixes)
git bisect good 2c075f38a708c578a752b738a45e8c26923eac2e
# bad: [76d4acf22b4847f6c7b2f9042366fbdc3d20f578] Merge tag 'perf-kprobes-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect bad 76d4acf22b4847f6c7b2f9042366fbdc3d20f578
# bad: [f9b4240b074730f41c1ef8e0d695d10fb5bb1e27] Merge tag 'fixes-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
git bisect bad f9b4240b074730f41c1ef8e0d695d10fb5bb1e27
# good: [d889797530c66f699170233474eab3361471e808] Merge remote-tracking branch 'arm64/for-next/fixes' into for-next/core
git bisect good d889797530c66f699170233474eab3361471e808
# good: [2f6ea6fb88ab9d517644a098fc670b4d5dd1735e] s390/tape: remove unsupported PM functions
git bisect good 2f6ea6fb88ab9d517644a098fc670b4d5dd1735e
# bad: [586592478b1fa8bb8cd6875a9191468e9b1a8b13] Merge tag 's390-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
git bisect bad 586592478b1fa8bb8cd6875a9191468e9b1a8b13
# good: [0b03beface02d519693edb8020f9811c67d5c88f] Merge tag 'm68k-for-v5.11-tag1' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k
git bisect good 0b03beface02d519693edb8020f9811c67d5c88f
# bad: [613775d62ec60202f98d2c5f520e6e9ba6dd4ac4] s390/kexec_file: fix diag308 subcode when loading crash kernel
git bisect bad 613775d62ec60202f98d2c5f520e6e9ba6dd4ac4
# good: [796cfabde5b23e1e506994fd11d2609ec2818e8d] s390/cio: remove pm support from IO subchannel drivers
git bisect good 796cfabde5b23e1e506994fd11d2609ec2818e8d
# bad: [8cc0dcfdc1c0e0be107d0288f9c0cf1f4201be62] s390/cio: remove pm support from ccw bus driver
git bisect bad 8cc0dcfdc1c0e0be107d0288f9c0cf1f4201be62
# good: [ef2eea78a6f363a58c909b7a0fd002df7cc52991] s390/cio: remove pm support from css-bus driver
git bisect good ef2eea78a6f363a58c909b7a0fd002df7cc52991
# first bad commit: [8cc0dcfdc1c0e0be107d0288f9c0cf1f4201be62] s390/cio: remove pm support from ccw bus driver