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Date:   Tue, 23 Apr 2019 11:09:22 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Stephen Boyd <sboyd@kernel.org>
Cc:     Michael Turquette <mturquette@baylibre.com>,
        linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        Russell King <linux@armlinux.org.uk>,
        Jeffrey Hugo <jhugo@codeaurora.org>,
        Chen-Yu Tsai <wens@csie.org>
Subject: Re: [PATCH v4 9/9] clk: fixed-factor: Let clk framework find parent
Message-ID: <20190423180922.GA3463@roeck-us.net>
References: <20190412183150.102131-1-sboyd@kernel.org>
 <20190412183150.102131-10-sboyd@kernel.org>
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Hi,

On Fri, Apr 12, 2019 at 11:31:50AM -0700, Stephen Boyd wrote:
> Convert this driver to a more modern way of specifying parents now that
> we have a way to specify clk parents by DT index. This lets us nicely
> avoid a problem where a parent clk name isn't know because the parent
> clk hasn't been registered yet.
> 
> Cc: Miquel Raynal <miquel.raynal@bootlin.com>
> Cc: Jerome Brunet <jbrunet@baylibre.com>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Michael Turquette <mturquette@baylibre.com>
> Cc: Jeffrey Hugo <jhugo@codeaurora.org>
> Cc: Chen-Yu Tsai <wens@csie.org>
> Signed-off-by: Stephen Boyd <sboyd@kernel.org>

This patch causes a substantial number of crashes of qemu boot tests in -next.

Failed tests: 
	arm:versatilepb:versatile_defconfig:aeabi:pci:scsi:mem128:versatile-pb:rootfs 
	arm:versatilepb:versatile_defconfig:aeabi:pci:mem128:versatile-pb:initrd 
	arm:versatileab:versatile_defconfig:mem128:versatile-ab:initrd 
	arm:beagle:multi_v7_defconfig:sd:mem256:omap3-beagle:rootfs 
	arm:beaglexm:multi_v7_defconfig:sd:mem512:omap3-beagle-xm:rootfs 
	arm:overo:multi_v7_defconfig:sd:mem256:omap3-overo-tobi:rootfs 
	arm:realview-pb-a8:realview_defconfig:realview_pb:mem512:arm-realview-pba8:initrd 
	arm:realview-pbx-a9:realview_defconfig:realview_pb:arm-realview-pbx-a9:initrd 
	arm:realview-eb:realview_defconfig:realview_eb:mem512:arm-realview-eb:initrd 
	arm:realview-eb-mpcore:realview_defconfig:realview_eb:mem512:arm-realview-eb-11mp-ctrevb:initrd 
	arm:integratorcp:integrator_defconfig:mem128:integratorcp:initrd 
	arm:mps2-an385:mps2_defconfig:mps2-an385:initrd

Most of the time the crash happens too early to generate a log,
but here is one:

[    0.000000] [<2100bd59>] (unwind_backtrace) from [<2100b11f>] (show_stack+0xb/0xc)
[    0.000000] [<2100b11f>] (show_stack) from [<211b2d27>] (Ldiv0_64+0x9/0x1a)
[    0.000000] [<211b2d27>] (Ldiv0_64) from [<21038e87>] (clocks_calc_max_nsecs+0x1d/0x62)
[    0.000000] [<21038e87>] (clocks_calc_max_nsecs) from [<21038fb1>] (__clocksource_update_freq_scale+0xe5/0x11c)
[    0.000000] [<21038fb1>] (__clocksource_update_freq_scale) from [<21038ff1>] (__clocksource_register_scale+0x9/0x40)
[    0.000000] [<21038ff1>] (__clocksource_register_scale) from [<212a8713>] (mps2_timer_init+0xaf/0x29c)
[    0.000000] [<212a8713>] (mps2_timer_init) from [<212a85b1>] (timer_probe+0x49/0x80)
[    0.000000] [<212a85b1>] (timer_probe) from [<2129d639>] (start_kernel+0x1c5/0x2f4)
[    0.000000] [<2129d639>] (start_kernel) from [<00000000>] (  (null))
[    0.000000] clocksource: mps2-clksrc: mask: 0xffffffff max_cycles: 0x0, max_idle_ns: 0 ns
[    0.000000] Division by zero in kernel.

Reverting the crash fixes the problem. Bisect log attached.

Guenter

---
# bad: [76c938fcaa4b4a5d8f05fa907925d5043834964e] Add linux-next specific files for 20190423
# good: [085b7755808aa11f78ab9377257e1dad2e6fa4bb] Linux 5.1-rc6
git bisect start 'HEAD' 'v5.1-rc6'
# bad: [ed04f675fa2c22316d7b57bea1258a18a47537ea] Merge remote-tracking branch 'crypto/master'
git bisect bad ed04f675fa2c22316d7b57bea1258a18a47537ea
# bad: [f66d30ddc658fb37848e8e6297b1e658fa297e79] Merge remote-tracking branch 'hid/for-next'
git bisect bad f66d30ddc658fb37848e8e6297b1e658fa297e79
# good: [24523334fd0feef03f3dc42487c158c233455676] Merge remote-tracking branch 'tegra/for-next'
git bisect good 24523334fd0feef03f3dc42487c158c233455676
# bad: [4d5d5f95d0ef4ba470287a941d06600889760ab7] Merge remote-tracking branch 'btrfs-kdave/for-next'
git bisect bad 4d5d5f95d0ef4ba470287a941d06600889760ab7
# bad: [c8040e3c8ab0870b3dfa502cc931258fc04709c6] Merge remote-tracking branch 's390/features'
git bisect bad c8040e3c8ab0870b3dfa502cc931258fc04709c6
# bad: [4209fc3374cfa572aa2defb8ecafe94a9db3c7d4] Merge remote-tracking branch 'csky/linux-next'
git bisect bad 4209fc3374cfa572aa2defb8ecafe94a9db3c7d4
# good: [21eb35a1ae4db08d32e2b5a8d9fe476c16056511] Merge commit 'tags/clk-fixes-for-linus^0' into clk-next
git bisect good 21eb35a1ae4db08d32e2b5a8d9fe476c16056511
# good: [3f644cdb2351fe21cded6ee1e5c13ea7905c3a64] Merge branch 'clk-zynq' into clk-next
git bisect good 3f644cdb2351fe21cded6ee1e5c13ea7905c3a64
# bad: [0db9597d81d918605d4d36c87ab140228fe14150] Merge remote-tracking branch 'clk-samsung/for-next'
git bisect bad 0db9597d81d918605d4d36c87ab140228fe14150
# bad: [e04cb6e358cbcdce56cda317725131252ecf6ccd] Merge branch 'clk-parent-rewrite-1' into clk-next
git bisect bad e04cb6e358cbcdce56cda317725131252ecf6ccd
# good: [89a5ddcc799d5d7dbcf6197b79dafc1dc9f997f5] clk: Add of_clk_hw_register() API for early clk drivers
git bisect good 89a5ddcc799d5d7dbcf6197b79dafc1dc9f997f5
# good: [dde4eff47c82c52a72af333d9e55370eee6d95d6] clk: Look for parents with clkdev based clk_lookups
git bisect good dde4eff47c82c52a72af333d9e55370eee6d95d6
# bad: [ecbf3f1795fda56122632c1d024cfd0d3f4fe353] clk: fixed-factor: Let clk framework find parent
git bisect bad ecbf3f1795fda56122632c1d024cfd0d3f4fe353
# good: [601b6e93304a65f8f7c37168763ab9ba5b195ce5] clk: Allow parents to be specified via clkspec index
git bisect good 601b6e93304a65f8f7c37168763ab9ba5b195ce5
# first bad commit: [ecbf3f1795fda56122632c1d024cfd0d3f4fe353] clk: fixed-factor: Let clk framework find parent