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Subject: Re: [PATCH 00/13 v2] Regulator ena_gpiod fixups
To:     Linus Walleij <linus.walleij@linaro.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        Charles Keepax <ckeepax@opensource.cirrus.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>
From:   Marek Szyprowski <m.szyprowski@samsung.com>
Message-ID: <d6b5f384-51aa-0e99-7e88-a1debcf5eca3@samsung.com>
Date:   Mon, 3 Dec 2018 15:35:37 +0100
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References: <CGME20181201154428epcas4p3a1a5c9c576027b1c56f8dd1510b32187@epcas4p3.samsung.com>
        <20181201154151.14890-1-linus.walleij@linaro.org>
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Hi Linus,

On 2018-12-01 16:41, Linus Walleij wrote:
> Here is a second iteration of these fixups after thinking
> over Charles Keepax excellent comments on the first series
> of fixes.
>
> To make sure GPIO descriptors are never left dangling
> (as far as I can tell!) I use this stepwise approach:
>
> 1. Fix the regulator_register() in the core to guarantee
>    that after calling this with a valid GPIO descriptor
>    in ena_gpiod it will be gpiod_put() if there is any
>    problem.
>
> 2. Fix up simple descriptor consumers to just gpiod_get()
>    and let the core take over the descriptor. Only handle
>    the errorpath up to this point.
>
> 3. Export gpiod_get_from_of_node() and let max77686
>    obtain a GPIO descriptor from the device tree without
>    any devres make-up in the DT parsing callback.
>
> 4. Invent devm_gpiod_unhinge() that will remove the devres
>    monitoring of a devm_* allocated GPIO descriptor
>    right before handling it over to the regulator core,
>    and use this in the otherwise hairy da9211,
>    s5m8767, tps65090 and s2mps11 drivers.


The idea is good imho, but it looks that there are some missing cases in
the code. Here are some logs from the boards I have access to:


Artik5 evaluation board (arch/arm/boot/dts/exynos3250-artik5-eval.dtb):

s2mps11-pmic s2mps14-regulator: Failed to get control GPIO for 11/LDO12
------------[ cut here ]------------
WARNING: CPU: 1 PID: 1 at drivers/gpio/gpiolib-devres.c:336
s2mps11_pmic_probe+0x1c4/0x49c
Modules linked in:
CPU: 1 PID: 1 Comm: swapper/0 Not tainted
4.20.0-rc5-next-20181203-00020-gf6d64d46ca8c #1156
Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[<c01125fc>] (unwind_backtrace) from [<c010e140>] (show_stack+0x10/0x14)
[<c010e140>] (show_stack) from [<c0a510bc>] (dump_stack+0x98/0xc4)
[<c0a510bc>] (dump_stack) from [<c0127078>] (__warn+0x10c/0x124)
[<c0127078>] (__warn) from [<c01271a4>] (warn_slowpath_null+0x40/0x48)
[<c01271a4>] (warn_slowpath_null) from [<c04e5c94>]
(s2mps11_pmic_probe+0x1c4/0x49c)
[<c04e5c94>] (s2mps11_pmic_probe) from [<c0583e60>]
(platform_drv_probe+0x48/0x9c)
[<c0583e60>] (platform_drv_probe) from [<c0581858>]
(really_probe+0x274/0x400)
[<c0581858>] (really_probe) from [<c0581ba0>]
(driver_probe_device+0x78/0x1b8)
[<c0581ba0>] (driver_probe_device) from [<c0581e08>]
(__driver_attach+0x128/0x144)
[<c0581e08>] (__driver_attach) from [<c057f71c>]
(bus_for_each_dev+0x68/0xb4)
[<c057f71c>] (bus_for_each_dev) from [<c0580a1c>]
(bus_add_driver+0x1a8/0x268)
[<c0580a1c>] (bus_add_driver) from [<c0582e44>] (driver_register+0x78/0x10c)
[<c0582e44>] (driver_register) from [<c0103154>]
(do_one_initcall+0x8c/0x410)
[<c0103154>] (do_one_initcall) from [<c0f0124c>]
(kernel_init_freeable+0x3c8/0x4d0)
[<c0f0124c>] (kernel_init_freeable) from [<c0a6afd4>]
(kernel_init+0x8/0x10c)
random: fast init done
[<c0a6afd4>] (kernel_init) from [<c01010b4>] (ret_from_fork+0x14/0x20)
Exception stack(0xd8cc1fb0 to 0xd8cc1ff8)
1fa0:                                     00000000 00000000 00000000
00000000
1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000
1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
irq event stamp: 98209
hardirqs last  enabled at (98217): [<c0192e14>] console_unlock+0x4ac/0x698
hardirqs last disabled at (98256): [<c0192a34>] console_unlock+0xcc/0x698
softirqs last  enabled at (98276): [<c0102618>] __do_softirq+0x4f0/0x5e0
softirqs last disabled at (98289): [<c012f2f4>] irq_exit+0x160/0x16c
---[ end trace fed5502b2c7cd57b ]---
Unable to handle kernel paging request at virtual address fffffff0
pgd = (ptrval)
[fffffff0] *pgd=597ce841, *pte=00000000, *ppte=00000000
Internal error: Oops: 27 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 1 PID: 1 Comm: swapper/0 Tainted: G        W        
4.20.0-rc5-next-20181203-00020-gf6d64d46ca8c #1156
Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
PC is at devm_gpiod_match+0x4/0x18
LR is at devres_remove+0x68/0xb8
...
Flags: NzCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 10c5387d  Table: 4000406a  DAC: 00000051
Process swapper/0 (pid: 1, stack limit = 0x(ptrval))
Stack: (0xd8cc1d58 to 0xd8cc2000)
...
[<c04a6f1c>] (devm_gpiod_match) from [<c05854b8>] (devres_remove+0x68/0xb8)
[<c05854b8>] (devres_remove) from [<c0585cdc>] (devres_destroy+0x8/0x24)
[<c0585cdc>] (devres_destroy) from [<c04a74a4>]
(devm_gpiod_unhinge+0x1c/0x38)
[<c04a74a4>] (devm_gpiod_unhinge) from [<c04e5c94>]
(s2mps11_pmic_probe+0x1c4/0x49c)
[<c04e5c94>] (s2mps11_pmic_probe) from [<c0583e60>]
(platform_drv_probe+0x48/0x9c)
[<c0583e60>] (platform_drv_probe) from [<c0581858>]
(really_probe+0x274/0x400)
[<c0581858>] (really_probe) from [<c0581ba0>]
(driver_probe_device+0x78/0x1b8)
[<c0581ba0>] (driver_probe_device) from [<c0581e08>]
(__driver_attach+0x128/0x144)
[<c0581e08>] (__driver_attach) from [<c057f71c>]
(bus_for_each_dev+0x68/0xb4)
[<c057f71c>] (bus_for_each_dev) from [<c0580a1c>]
(bus_add_driver+0x1a8/0x268)
[<c0580a1c>] (bus_add_driver) from [<c0582e44>] (driver_register+0x78/0x10c)
[<c0582e44>] (driver_register) from [<c0103154>]
(do_one_initcall+0x8c/0x410)
[<c0103154>] (do_one_initcall) from [<c0f0124c>]
(kernel_init_freeable+0x3c8/0x4d0)
[<c0f0124c>] (kernel_init_freeable) from [<c0a6afd4>]
(kernel_init+0x8/0x10c)
[<c0a6afd4>] (kernel_init) from [<c01010b4>] (ret_from_fork+0x14/0x20)
Exception stack(0xd8cc1fb0 to 0xd8cc1ff8)
...
---[ end trace fed5502b2c7cd57c ]---


Rinato (arch/arm/boot/dts/exynos3250-rinato.dtb):

s2mps11-pmic s2mps14-regulator: Failed to get control GPIO for 11/LDO12
random: fast init done
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at drivers/gpio/gpiolib-devres.c:336
s2mps11_pmic_probe+0x1c4/0x49c
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted
4.20.0-rc5-next-20181203-00020-gf6d64d46ca8c #1156
Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[<c01125fc>] (unwind_backtrace) from [<c010e140>] (show_stack+0x10/0x14)
[<c010e140>] (show_stack) from [<c0a510bc>] (dump_stack+0x98/0xc4)
[<c0a510bc>] (dump_stack) from [<c0127078>] (__warn+0x10c/0x124)
[<c0127078>] (__warn) from [<c01271a4>] (warn_slowpath_null+0x40/0x48)
[<c01271a4>] (warn_slowpath_null) from [<c04e5c94>]
(s2mps11_pmic_probe+0x1c4/0x49c)
[<c04e5c94>] (s2mps11_pmic_probe) from [<c0583e60>]
(platform_drv_probe+0x48/0x9c)
[<c0583e60>] (platform_drv_probe) from [<c0581858>]
(really_probe+0x274/0x400)
[<c0581858>] (really_probe) from [<c0581ba0>]
(driver_probe_device+0x78/0x1b8)
[<c0581ba0>] (driver_probe_device) from [<c0581e08>]
(__driver_attach+0x128/0x144)
[<c0581e08>] (__driver_attach) from [<c057f71c>]
(bus_for_each_dev+0x68/0xb4)
[<c057f71c>] (bus_for_each_dev) from [<c0580a1c>]
(bus_add_driver+0x1a8/0x268)
[<c0580a1c>] (bus_add_driver) from [<c0582e44>] (driver_register+0x78/0x10c)
[<c0582e44>] (driver_register) from [<c0103154>]
(do_one_initcall+0x8c/0x410)
[<c0103154>] (do_one_initcall) from [<c0f0124c>]
(kernel_init_freeable+0x3c8/0x4d0)
[<c0f0124c>] (kernel_init_freeable) from [<c0a6afd4>]
(kernel_init+0x8/0x10c)
[<c0a6afd4>] (kernel_init) from [<c01010b4>] (ret_from_fork+0x14/0x20)
Exception stack(0xd94c1fb0 to 0xd94c1ff8)
...
irq event stamp: 114729
hardirqs last  enabled at (114747): [<c0192e14>] console_unlock+0x4ac/0x698
hardirqs last disabled at (114764): [<c0192a34>] console_unlock+0xcc/0x698
softirqs last  enabled at (114762): [<c0102618>] __do_softirq+0x4f0/0x5e0
softirqs last disabled at (114781): [<c012f2f4>] irq_exit+0x160/0x16c
---[ end trace 5961f9fa5249019f ]---
Unable to handle kernel paging request at virtual address fffffff0
pgd = (ptrval)
[fffffff0] *pgd=5fece841, *pte=00000000, *ppte=00000000
Internal error: Oops: 27 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W        
4.20.0-rc5-next-20181203-00020-gf6d64d46ca8c #1156
Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
PC is at devm_gpiod_match+0x4/0x18
LR is at devres_remove+0x68/0xb8
...
Flags: NzCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 10c5387d  Table: 4000406a  DAC: 00000051
Process swapper/0 (pid: 1, stack limit = 0x(ptrval))
Stack: (0xd94c1d58 to 0xd94c2000)
...
[<c04a6f1c>] (devm_gpiod_match) from [<c05854b8>] (devres_remove+0x68/0xb8)
[<c05854b8>] (devres_remove) from [<c0585cdc>] (devres_destroy+0x8/0x24)
[<c0585cdc>] (devres_destroy) from [<c04a74a4>]
(devm_gpiod_unhinge+0x1c/0x38)
[<c04a74a4>] (devm_gpiod_unhinge) from [<c04e5c94>]
(s2mps11_pmic_probe+0x1c4/0x49c)
[<c04e5c94>] (s2mps11_pmic_probe) from [<c0583e60>]
(platform_drv_probe+0x48/0x9c)
[<c0583e60>] (platform_drv_probe) from [<c0581858>]
(really_probe+0x274/0x400)
[<c0581858>] (really_probe) from [<c0581ba0>]
(driver_probe_device+0x78/0x1b8)
[<c0581ba0>] (driver_probe_device) from [<c0581e08>]
(__driver_attach+0x128/0x144)
[<c0581e08>] (__driver_attach) from [<c057f71c>]
(bus_for_each_dev+0x68/0xb4)
[<c057f71c>] (bus_for_each_dev) from [<c0580a1c>]
(bus_add_driver+0x1a8/0x268)
[<c0580a1c>] (bus_add_driver) from [<c0582e44>] (driver_register+0x78/0x10c)
[<c0582e44>] (driver_register) from [<c0103154>]
(do_one_initcall+0x8c/0x410)
[<c0103154>] (do_one_initcall) from [<c0f0124c>]
(kernel_init_freeable+0x3c8/0x4d0)
[<c0f0124c>] (kernel_init_freeable) from [<c0a6afd4>]
(kernel_init+0x8/0x10c)
[<c0a6afd4>] (kernel_init) from [<c01010b4>] (ret_from_fork+0x14/0x20)
Exception stack(0xd94c1fb0 to 0xd94c1ff8)
...
---[ end trace 5961f9fa524901a0 ]---


Other boards with other variants of s2mps11 or other PMICs works fine.


>
> Linus Walleij (13):
>   regulator: core: Track dangling GPIO descriptors
>   regulator: fixed: Let core handle GPIO descriptor
>   regulator: lm363x: Let core handle GPIO descriptor
>   regulator: lp8788-ldo: Let core handle GPIO descriptor
>   regulator: max8952: Let core handle GPIO descriptor
>   regulator: max8973: Let core handle GPIO descriptor
>   gpio: Export gpiod_get_from_of_node()
>   regulator: max77686: Let core handle GPIO descriptor
>   gpio: Add devm_gpiod_unhinge()
>   regulator: da9211: Hand over GPIO to regulator core
>   regulator: s5m8767: Hand over GPIO to regulator core
>   regulator: tps65090: Hand over GPIO to regulator core
>   regulator: s2mps11: Hand over GPIO to regulator core
>
>  Documentation/driver-model/devres.txt  |  1 +
>  drivers/gpio/gpiolib-devres.c          | 17 ++++++++
>  drivers/gpio/gpiolib.h                 |  6 ---
>  drivers/regulator/core.c               | 55 +++++++++++++++++++++-----
>  drivers/regulator/da9211-regulator.c   |  6 +++
>  drivers/regulator/fixed.c              |  6 ++-
>  drivers/regulator/lm363x-regulator.c   |  8 +++-
>  drivers/regulator/lp8788-ldo.c         |  8 +++-
>  drivers/regulator/max77686-regulator.c | 14 ++++---
>  drivers/regulator/max8952.c            | 10 +++--
>  drivers/regulator/max8973-regulator.c  | 23 +++++++----
>  drivers/regulator/s2mps11.c            |  7 +++-
>  drivers/regulator/s5m8767.c            |  9 ++++-
>  drivers/regulator/tps65090-regulator.c |  6 +++
>  include/linux/gpio/consumer.h          | 23 +++++++++++
>  15 files changed, 161 insertions(+), 38 deletions(-)
>
Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland