Re: [PATCH 0/7] PM / devfreq: Add NoCP devfreq-event and support busfreq on exyno5422-odroidxu3

[Anand Moon <linux.amoon@gmail.com>]

Hi Chanwoo,

On 8 April 2016 at 10:30, Chanwoo Choi <cw00.choi@samsung.com> wrote:
> This patchset support the AMBA bus frequency scaling on Exynos5422-based
> Odroid-XU3 board. But, this series only support the bus frequency scaling
> for INT (Internal) block using VDD_INT power line.
>
> Also, to support the bus frequency scaling for Exynos542x SoC,
> Exynos542x SoC has the specific 'NoC (Network on Chip) Probe' device
> to measure the transfered data traffic on NoC (Network on Chip)
> instead of PPMU (Platform Performance Monitoring Unit). NoC Probe device
> provide the utilization for INT block of Exynos542x SoC.
>
> The generic exynos-bus frequency driver uses the 'NoC Probe' devfreq-event
> device (drivers/devfreq/event/exynos-nocp.c) without any modification.
> Just add the phandle of 'NoC Probe' dt node to bus dt node.
>
> Depend on:
> This patchset depends on patch[1] which support the generic exynos-bus
> frequency driver.
>
> [1] https://lkml.org/lkml/2016/4/8/14
> - [PATCH v8 00/20] PM / devferq: Add generic exynos bus frequency driver and new passive governor
>
> Chanwoo Choi (7):
>   PM / devfreq: event: Add new Exynos NoC probe driver
>   PM / devfreq: exynos: Add the detailed correlation for Exynos5422 bus
>   ARM: dts: Add NoC Probe dt node for Exynos542x SoC
>   dt-bindings: clock: Add the clock id for ACLK clock of Exynos542x SoC
>   clk: samsung: exynos542x: Add the clock id for ACLK
>   ARM: dts: Add bus nodes using VDD_INT for Exynos542x SoC
>   ARM: dts: Add support of Bus frequency using VDD_INT for exynos5422-odroidxu3
>
>  .../bindings/devfreq/event/exynos-nocp.txt         |  86 +++++
>  .../devicetree/bindings/devfreq/exynos-bus.txt     |  19 +
>  arch/arm/boot/dts/exynos5420.dtsi                  | 407 +++++++++++++++++++++
>  arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi |  99 +++++
>  drivers/clk/samsung/clk-exynos5420.c               |  85 +++--
>  drivers/devfreq/event/Kconfig                      |   8 +
>  drivers/devfreq/event/Makefile                     |   2 +
>  drivers/devfreq/event/exynos-nocp.c                | 247 +++++++++++++
>  drivers/devfreq/event/exynos-nocp.h                |  78 ++++
>  include/dt-bindings/clock/exynos5420.h             |  24 +-
>  10 files changed, 1024 insertions(+), 31 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/devfreq/event/exynos-nocp.txt
>  create mode 100644 drivers/devfreq/event/exynos-nocp.c
>  create mode 100644 drivers/devfreq/event/exynos-nocp.h
>
> --
> 1.9.1
>

I am observing following deadlock. Both on Odroid U3 and Odroid XU4.

[    7.718372] [ INFO: possible recursive locking detected ]
[    7.723747] 4.6.0-rc2-xu4ml #4 Not tainted
[    7.727817] ---------------------------------------------
[    7.733190] kworker/u16:1/136 is trying to acquire lock:
[    7.738476]  (&devfreq->lock){+.+.+.}, at: [<c05be41c>]
update_devfreq_passive+0x2c/0x88
[    7.746534]
[    7.746534] but task is already holding lock:
[    7.752339]  (&devfreq->lock){+.+.+.}, at: [<c05bd838>]
devfreq_monitor+0x1c/0x78
[    7.759791]
[    7.759791] other info that might help us debug this:
[    7.766291]  Possible unsafe locking scenario:
[    7.766291]
[    7.766307] usb 5-1: new high-speed USB device number 2 using xhci-hcd
[    7.778682]        CPU0
[    7.781107]        ----
[    7.783533]   lock(&devfreq->lock);
[    7.786999]   lock(&devfreq->lock);
[    7.790467]
[    7.790467]  *** DEADLOCK ***
[    7.790467]
[    7.796359]  May be due to missing lock nesting notation
[    7.796359]
[    7.803120] 4 locks held by kworker/u16:1/136:
[    7.807537]  #0:  ("%s"("devfreq_wq")){.+.+..}, at: [<c013b41c>]
process_one_work+0x13c/0x454
[    7.816029]  #1:  ((&(&devfreq->work)->work)){+.+...}, at:
[<c013b41c>] process_one_work+0x13c/0x454
[    7.825128]  #2:  (&devfreq->lock){+.+.+.}, at: [<c05bd838>]
devfreq_monitor+0x1c/0x78
[    7.833013]  #3:  (&nh->srcu){......}, at: [<c014309c>]
__srcu_notifier_call_chain+0x54/0xe0
[    7.841419]
[    7.841419] stack backtrace:
[    7.845758] CPU: 1 PID: 136 Comm: kworker/u16:1 Not tainted
4.6.0-rc2-xu4ml #4
[    7.852946] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[    7.859017] Workqueue: devfreq_wq devfreq_monitor
[    7.863717] [<c010eb48>] (unwind_backtrace) from [<c010b884>]
(show_stack+0x10/0x14)
[    7.871417] [<c010b884>] (show_stack) from [<c037715c>]
(dump_stack+0xa4/0xd0)
[    7.878613] [<c037715c>] (dump_stack) from [<c017112c>]
(__lock_acquire+0x1ce8/0x207c)
[    7.886492] [<c017112c>] (__lock_acquire) from [<c0172010>]
(lock_acquire+0x90/0xd4)
[    7.892726] usb 5-1: New USB device found, idVendor=0bda, idProduct=8153
[    7.892737] usb 5-1: New USB device strings: Mfr=1, Product=2, SerialNumber=6
[    7.892745] usb 5-1: Product: USB 10/100/1000 LAN
[    7.892753] usb 5-1: Manufacturer: Realtek
[    7.892761] usb 5-1: SerialNumber: 000001000000
[    7.921248] [<c0172010>] (lock_acquire) from [<c075d298>]
(mutex_lock_nested+0x78/0x4ec)
[    7.929301] [<c075d298>] (mutex_lock_nested) from [<c05be41c>]
(update_devfreq_passive+0x2c/0x88)
[    7.938138] [<c05be41c>] (update_devfreq_passive) from [<c05be4c0>]
(devfreq_passive_notifier_call+0x48/0x50)
[    7.948016] [<c05be4c0>] (devfreq_passive_notifier_call) from
[<c0142d84>] (notifier_call_chain+0x54/0xa4)
[    7.957633] [<c0142d84>] (notifier_call_chain) from [<c01430e0>]
(__srcu_notifier_call_chain+0x98/0xe0)
[    7.966991] [<c01430e0>] (__srcu_notifier_call_chain) from
[<c0143140>] (srcu_notifier_call_chain+0x18/0x20)
[    7.976783] [<c0143140>] (srcu_notifier_call_chain) from
[<c05bd774>] (update_devfreq+0xe4/0x18c)
[    7.985622] [<c05bd774>] (update_devfreq) from [<c05bd840>]
(devfreq_monitor+0x24/0x78)
[    7.993595] [<c05bd840>] (devfreq_monitor) from [<c013b48c>]
(process_one_work+0x1ac/0x454)
[    8.001913] [<c013b48c>] (process_one_work) from [<c013b784>]
(worker_thread+0x50/0x508)
[    8.009976] [<c013b784>] (worker_thread) from [<c0141cf4>]
(kthread+0xf8/0x110)
[    8.017254] [<c0141cf4>] (kthread) from [<c0107750>]
(ret_from_fork+0x14/0x24)

Best Regards
-Anand Moon