Hi Fabio,
thank you for your response.
Could you tell me on which board precisely (on which DTS) has this issue occurred?
Also, I don't understand, did you boot successfully and you got only a lockdep
warning or you encountered an actual deadlock?
Best regards,
Maciej Purski
On 03/05/2018 01:34 PM, Fabio Estevam wrote:
Hi Maciej,
On Fri, Mar 2, 2018 at 5:42 AM, Maciej Purski <m.purski@xxxxxxxxxxx> wrote:
Hi all,
this patchset adds a new mechanism to the framework - regulators' coupling.
On Odroid XU3/4 and other Exynos5422 based boards there is a case, that
different devices on the board are supplied by different regulators
with non-fixed voltages. If one of these devices temporarily requires
higher voltage, there might occur a situation that the spread between
devices' voltages is so high, that there is a risk of changing
'high' and 'low' states on the interconnection between devices powered
by those regulators.
Algorithmicaly the problem was solved by:
Inderpal Singh <inderpal.s@xxxxxxxxxxx>
Doug Anderson <dianders@xxxxxxxxxxxx>
The discussion on that subject can be found here:
https://lkml.org/lkml/2014/4/29/28
Therefore this patchset is an attempt to apply the idea to regulators core
as concluded in the discussion by Mark Brown and Doug Anderson.
This feature is required to enable support for generic CPUfreq
and devfreq drivers for the mentioned boards.
Note on the locking model:
When balancing voltage of a group of coupled regulators, we lock all
of them for the whole operation. When voltage of an individual regulator
is about to change, its suppliers are additionally locked.
The current assumption is that an uncoupled regulator is a special case
of a coupled one, so they should share a common voltage setting path.
This series breaks has reached linux-next 20180305 and it breaks
booting on imx6:
[ 0.269646] imx-pgc-pd imx-pgc-power-domain.0: Linked as a consumer
to 20dc000.gpc
[ 0.270348]
[ 0.270363] ============================================
[ 0.270373] WARNING: possible recursive locking detected
[ 0.270385] 4.16.0-rc3-next-20180305 #156 Not tainted
[ 0.270397] --------------------------------------------
[ 0.270408] swapper/0/1 is trying to acquire lock:
[ 0.270419] (&rdev->mutex){+.+.}, at: [<c04d80c4>]
regulator_lock_supply+0x24/0x44
[ 0.270460]
[ 0.270460] but task is already holding lock:
[ 0.270471] (&rdev->mutex){+.+.}, at: [<c04dc6e4>]
regulator_enable+0x78/0x298
[ 0.270502]
[ 0.270502] other info that might help us debug this:
[ 0.270513] Possible unsafe locking scenario:
[ 0.270513]
[ 0.270523] CPU0
[ 0.270532] ----
[ 0.270540] lock(&rdev->mutex);
[ 0.270555] lock(&rdev->mutex);
[ 0.270572]
[ 0.270572] *** DEADLOCK ***
[ 0.270572]
[ 0.270585] May be due to missing lock nesting notation
[ 0.270585]
[ 0.270598] 3 locks held by swapper/0/1:
[ 0.270606] #0: (&dev->mutex){....}, at: [<c057f368>]
__driver_attach+0x58/0xcc
[ 0.270642] #1: (&dev->mutex){....}, at: [<c057f378>]
__driver_attach+0x68/0xcc
[ 0.270672] #2: (&rdev->mutex){+.+.}, at: [<c04dc6e4>]
regulator_enable+0x78/0x298
[ 0.270701]
[ 0.270701] stack backtrace:
[ 0.270719] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
4.16.0-rc3-next-20180305 #156
[ 0.270731] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 0.270741] Backtrace:
[ 0.270767] [<c010d154>] (dump_backtrace) from [<c010d414>]
(show_stack+0x18/0x1c)
[ 0.270783] r7:00000000 r6:60000093 r5:00000000 r4:c1078360
[ 0.270805] [<c010d3fc>] (show_stack) from [<c0a4724c>]
(dump_stack+0xb4/0xe8)
[ 0.270830] [<c0a47198>] (dump_stack) from [<c0174f4c>]
(__lock_acquire+0x13a4/0x199c)
[ 0.270848] r9:c17d75fc r8:c11ae35c r7:c17c73b0 r6:ec060000
r5:ec060570 r4:c11ae35c
[ 0.270867] [<c0173ba8>] (__lock_acquire) from [<c0175d68>]
(lock_acquire+0x70/0x90)
[ 0.270883] r10:00000000 r9:ec195800 r8:00000001 r7:00000001
r6:60000013 r5:00000000
[ 0.270893] r4:ffffe000
[ 0.270914] [<c0175cf8>] (lock_acquire) from [<c0a60760>]
(__mutex_lock+0x64/0x978)
[ 0.270929] r8:00000001 r7:00000001 r6:00000000 r5:00000000 r4:ec00b89c
[ 0.270947] [<c0a606fc>] (__mutex_lock) from [<c0a61098>]
(mutex_lock_nested+0x24/0x2c)
[ 0.270963] r10:00000000 r9:ec195800 r8:00000001 r7:00000001
r6:ec195800 r5:00000000
[ 0.270975] r4:ec00b800
[ 0.270992] [<c0a61074>] (mutex_lock_nested) from [<c04d80c4>]
(regulator_lock_supply+0x24/0x44)
[ 0.271013] [<c04d80a0>] (regulator_lock_supply) from [<c04da9b0>]
(regulator_balance_voltage+0x298/0x584)
[ 0.271024] r5:000b1008 r4:ec195800
[ 0.271042] [<c04da718>] (regulator_balance_voltage) from
[<c04dc748>] (regulator_enable+0xdc/0x298)
[ 0.271059] r10:00000000 r9:00000000 r8:00000001 r7:00000001
r6:ec195800 r5:ec195824
[ 0.271069] r4:00000001
[ 0.271086] [<c04dc66c>] (regulator_enable) from [<c04d6dd8>]
(imx6_pm_domain_power_on+0x30/0x1b4)
[ 0.271102] r9:00000000 r8:c102d114 r7:c1008908 r6:c102d114
r5:ec3d7a00 r4:ec3d7a00
[ 0.271119] [<c04d6da8>] (imx6_pm_domain_power_on) from
[<c04d6d18>] (imx_pgc_power_domain_probe+0x64/0xf4)
[ 0.271135] r8:c102d114 r7:ec49c810 r6:c102d114 r5:ec49c800 r4:ec3d7a00
[ 0.271153] [<c04d6cb4>] (imx_pgc_power_domain_probe) from
[<c0580ef0>] (platform_drv_probe+0x54/0xb8)
[ 0.271168] r7:fffffdfb r6:c102d114 r5:ec49c810 r4:ec49c810
[ 0.271189] [<c0580e9c>] (platform_drv_probe) from [<c057f288>]
(driver_probe_device+0x2b0/0x338)
[ 0.271204] r7:c17e234c r6:00000000 r5:c17e2348 r4:ec49c810
[ 0.271222] [<c057efd8>] (driver_probe_device) from [<c057f3d8>]
(__driver_attach+0xc8/0xcc)
[ 0.271237] r10:c0f00630 r9:00000000 r8:c1008908 r7:c1008908
r6:ec49c844 r5:c102d114
[ 0.271248] r4:ec49c810 r3:00000000
[ 0.271267] [<c057f310>] (__driver_attach) from [<c057d348>]
(bus_for_each_dev+0x6c/0xbc)
[ 0.271280] r7:c1008908 r6:c057f310 r5:c102d114 r4:00000000
[ 0.271298] [<c057d2dc>] (bus_for_each_dev) from [<c057eb64>]
(driver_attach+0x20/0x28)
[ 0.271314] r7:00000000 r6:c103b0a8 r5:ec479b00 r4:c102d114
[ 0.271332] [<c057eb44>] (driver_attach) from [<c057e588>]
(bus_add_driver+0x18c/0x214)
[ 0.271351] [<c057e3fc>] (bus_add_driver) from [<c057fdbc>]
(driver_register+0x80/0x100)
[ 0.271366] r7:c0e125e4 r6:c0f63850 r5:c0f41c18 r4:c102d114
[ 0.271383] [<c057fd3c>] (driver_register) from [<c0580e44>]
(__platform_driver_register+0x38/0x4c)
[ 0.271396] r5:c0f41c18 r4:ffffe000
[ 0.271418] [<c0580e0c>] (__platform_driver_register) from
[<c0f41c30>] (imx_pgc_power_domain_driver_init+0x18/0x20)
[ 0.271438] [<c0f41c18>] (imx_pgc_power_domain_driver_init) from
[<c0102764>] (do_one_initcall+0x50/0x1a0)
[ 0.271464] [<c0102714>] (do_one_initcall) from [<c0f00f04>]
(kernel_init_freeable+0x118/0x1d0)
[ 0.271481] r9:c0f63858 r8:000000f2 r7:c0e125e4 r6:c0f63850
r5:c1079f80 r4:c0f77ab4
[ 0.271508] [<c0f00dec>] (kernel_init_freeable) from [<c0a5c6f0>]
(kernel_init+0x10/0x118)
[ 0.271524] r10:00000000 r9:00000000 r8:00000000 r7:00000000
r6:00000000 r5:c0a5c6e0
[ 0.271533] r4:00000000
[ 0.271552] [<c0a5c6e0>] (kernel_init) from [<c01010b4>]
(ret_from_fork+0x14/0x20)
[ 0.271564] Exception stack(0xec069fb0 to 0xec069ff8)
[ 0.271579] 9fa0: 00000000
00000000 00000000 00000000
[ 0.271594] 9fc0: 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000
[ 0.271609] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 0.271621] r5:c0a5c6e0 r4:00000000
[ 0.271723] imx-pgc-pd imx-pgc-power-domain.1: Linked as a consumer
to 20dc000.gpc
[ 0.273566] 2020000.serial: ttymxc0 at MMIO 0x2020000 (irq = 26,
base_baud = 5000000) is a IMX
[ 1.660948] console [ttymxc0] enabled
[ 1.666242] 21ec000.serial: ttymxc2 at MMIO 0x21ec000 (irq = 65,
base_baud = 5000000) is a IMX
[ 1.683484] etnaviv etnaviv: bound 130000.gpu (ops gpu_ops)
[ 1.689464] etnaviv etnaviv: bound 134000.gpu (ops gpu_ops)
If I revert this series I am able to boot again.
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