[BISECTED] Regression v4.6-rc1 : nanosleep doesn't return on AT91SAM9

[Richard Genoud]

2016-05-10 15:58 GMT+02:00 Richard Genoud <richard.genoud at gmail.com>:
> Hi,
>
> Starting with 4.6-rc1, a sleep 1 doesn't return :
>
> execve("/bin/sleep", ["sleep", "1"], ["USER=root", "SHLVL=1",
> "OLDPWD=/var", "HOME=/", "TERM=vt102",
> "PATH=/sbin:/usr/sbin:/bin:/usr/bin", "SHELL=/bin/sh", "PWD=/"]) = 0
> uname({sysname="Linux", nodename="LNS",
> release="4.5.0-09406-g46e595a17dcf", version="#72 Tue May 10 15:41:34
> CEST 2016", machine="armv5tejl", domainname="(none)"}) = 0
> brk(0)                                  = 0x153000
> brk(0x153d20)                           = 0x153d20
> set_tls(0x1534c0, 0x14d1e4, 0, 0x153d20, 0x14e368) = 0
> readlink("/proc/self/exe", "/bin/busybox", 4096) = 12
> brk(0x174d20)                           = 0x174d20
> brk(0x175000)                           = 0x175000
> getuid32()                              = 0
> rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
> rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
> rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
> nanosleep({1, 0},
>
> And the heartbeat led doesn't blink anymore (full on), as if the
> timers never fire.
>
> The platform is an AT91SAM9G35-CM.
>
> git bisect gives a merge as the 1st bad commit :(
> first bad commit: [46e595a17dcf11404f713845ecb5b06b92a94e43] Merge tag
> 'armsoc-drivers' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc


I went a little further in tracking that down, starting from the merge
(1st bad commit) and reverting some commits.
It seems that the culprit is :
commit 863a81c3be1d931bdae6426e231add9334311f13
Author: Boris Brezillon <boris.brezillon at free-electrons.com>
Date:   Fri Sep 5 09:54:13 2014 +0200
    clk: at91: make use of syscon to share PMC registers in several drivers

Here are the commits I've reverted :

git log --oneline --decorate -20
849cdaa0cf04 (HEAD, tag: good) Revert "clk: at91: make use of syscon
to share PMC registers in several drivers"
4bd6dde95321 (tag: last_bad) Revert "clk: at91: make use of
syscon/regmap internally"
a56dacaa24c4 (tag: always_bad) Revert "clk: at91: remove IRQ handling
and use polling"
33edfe7a2de6 Revert "clk: at91: pmc: merge at91_pmc_init in atmel_pmc_probe"
0b22bb649eae Revert "clk: at91: pmc: move pmc structures to C file"
14994fdff366 Revert "ARM: at91: pm: simply call at91_pm_init"
6f0821175327 (tag: still_bad) Revert "ARM: at91: pm: find and remap the pmc"
b52bbf7fad1b Revert "ARM: at91: pm: move idle functions to pm.c"
dffb1a5f68b9 Revert "ARM: at91: remove useless includes and function prototypes"
db352691dcc1 Revert "usb: gadget: atmel: access the PMC using regmap"
f7b5433dbbc8 Revert "clk: at91: pmc: drop at91_pmc_base"
6e6dfc0d91c0 Revert "clk: at91: pmc: remove useless capacities handling"
ceddd3f88ada Revert "clk: at91: remove useless includes"
46e595a17dcf (tag: bad) Merge tag 'armsoc-drivers' of
git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
e3b1f64e04f5 Merge tag 'armsoc-defconfig' of
git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
915c56bc01d6 Merge tag 'armsoc-dt64' of
git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
5a6b7e53d035 Merge tag 'armsoc-dt' of
git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
8c6d4082fc6a Merge tag 'armsoc-arm64' of
git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
33b3d2e88c9e Merge tag 'armsoc-soc' of
git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
e88fa1b8b00a Merge tag 'armsoc-cleanup' of
git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc