Re: [PATCH v4 00/20] PM / devferq: Add generic exynos bus frequency driver and new passive governor

From: Tobias Jakobi
Date: Fri Feb 19 2016 - 10:05:50 EST

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Hello,

I've applied the patchset to 4.5-rc4 and I'm now encountering two
additional problems. The first related to debugfs entries, the second
cocerning RCU locking.

Here are the debugfs lines:
exynos-bus bus_dmc: device_opp_debug_create_link: Failed to create link
exynos-bus bus_dmc: _add_list_dev: Failed to register opp debugfs (-12)
exynos-bus bus_dmc: Looking up vdd-supply from device tree
exynos-bus: new bus device registered: bus_dmc (100000 KHz ~ 400000 KHz)
exynos-bus bus_acp: device_opp_debug_create_link: Failed to create link
exynos-bus bus_acp: _add_list_dev: Failed to register opp debugfs (-12)
exynos-bus: new bus device registered: bus_acp (100000 KHz ~ 267000 KHz)
exynos-bus bus_c2c: device_opp_debug_create_link: Failed to create link
exynos-bus bus_c2c: _add_list_dev: Failed to register opp debugfs (-12)
exynos-bus: new bus device registered: bus_c2c (100000 KHz ~ 400000 KHz)
exynos-bus bus_leftbus: device_opp_debug_create_link: Failed to create link
devfreq bus_dmc: Couldn't update frequency transition information.
exynos-bus bus_leftbus: _add_list_dev: Failed to register opp debugfs (-12)
exynos-bus bus_leftbus: Looking up vdd-supply from device tree

The RCU output is a bit longer, so I attached it.

With best wishes,
Tobias

Chanwoo Choi wrote:
> This patch-set includes the two features as following. The generic exynos bus
> frequency driver is able to support almost Exynos SoCs for bus frequency
> scaling. And the new passive governor is able to make the dependency on
> between devices for frequency/voltage scaling. I had posted the patch-set[2]
> with the similiar concept. This is is revised version for exynos bus frequency.
> - Generic exynos bus frequency driver
> - New passive governor of DEVFREQ framework
>
> Depend on:
> - next-20151210 tag of linux-next (master branch).
> - Merge the latest devfreq patches on devfreq.git[2] (for-rafael branch).
> [1] https://git.kernel.org/cgit/linux/kernel/git/mzx/devfreq.git/ (branch: for-rafael)
> [2] https://lkml.org/lkml/2015/1/7/872
> : [PATCHv3 0/8] devfreq: Add generic exynos memory-bus frequency driver
>
> Changes from v3:
> (https://lkml.org/lkml/2015/12/11/75)
> - Add the reviewed-by tag from Krzysztof Kozlowski (patch2/3/13/14/15/16/17)
> - Fix typo of the description on patch14
> - Modify the subject and description of patch17
> - Reorder the 'bus_xxx' device tree node alphabetically in
> both exynos3250-rinato/monk.dts and exynos4412-trats/odroidu3
>
> Changes from v2:
> (https://lkml.org/lkml/2015/12/8/869)
> - Fix typo on documentation
> - Modify the more appropriate sentence on patch description
> - Add the detailed description about both parent and passive bus device
> - Modify the DMC frequency for Exynos4x12 DMC bus (200MHz -> 267MHz)
> - Modify the voltage of 200MHz was included in Exynos3250 DMC bus (800mV -> 825mV)
> - Rename OPP nodes as 'opp@<opp-hz>'
> - Delete the duplicate 'opp-microvolt' property of passive devfreq device
> - Reorder the 'bus_xxx' device tree node alphabetically in exynos3250-rinato/monk.dts
> - Reorder the 'bus_xxx' device tree node alphabetically in exynos4412-trats/odroidu3
> - Add new exynos4412-ppmu-common.dtsi to remove the duplicate PPMU dt node
> on rinato/monk/trats2/odroid-u3 board
> - Add the log message if bus device is registered to devfreq framework successfully
> - Add the reviewed-by tag from Krzysztof Kozlowski
> - Add the tested-by tag from Anand Moon on Odroid U3
> - Add 'SAMSUNG BUS FREQUENCY DRIVER' entry to MAINTAINERS
>
> Changes from v1:
> (https://lkml.org/lkml/2015/11/26/260)
> - Check whether the instance of regulator is NULL or not
> when executing regulator_disable() because of only parent
> devfreq device has the regulator instance. After fixing it,
> the wake-up from suspend state is well working. (patch1)
> - Fix bug which checks 'bus-clk' instead of 'bus->regulator'
> after calling devm_clk_get() (on patch1)
> - Update the documentation to remove the description about
> DEVFREQ-EVENT subsystem (on patch2)
> - Add the full name of DMC (Dynamic Memory Controller) (on patch2)
> - Modify the detailed correlation of buses for Exynos3250
> on documentation (patch2)
> - Add the MFC bus node for Exynos3250 (on patch11, patch12)
> - Fix the duplicate frequency of bus_display on Exynos4x12.dtsi
> - Add the PPMU node for exynos4412-odroidu3
> - Add the support of bus frequency for exynos4412-odroidu3
>
> Detailed descirption for patch-set:
> 1. Add generic exynos bus frequency driver
> : This patch-set adds the generic exynos bus frequency driver for AXI bus
> of sub-blocks in exynos SoC. The Samsung Exynos SoC have the common
> architecture for bus between DRAM and sub-blocks in SoC.
>
> There are the different buses according to Exynos SoC because Exynos SoC
> has the differnt sub-blocks and bus speed. In spite of this difference
> among Exynos SoCs, this driver is able to support almost Exynos SoC by adding
> unique data of each bus in the devicetree file.
>
> In devicetree, each bus node has a bus clock, regulator, operation-point
> and devfreq-event devices which measure the utilization of each bus block.
>
> For example,
> - The bus of DMC block in exynos3250.dtsi are listed below:
>
> bus_dmc: bus_dmc {
> compatible = "samsung,exynos-bus";
> clocks = <&cmu_dmc CLK_DIV_DMC>;
> clock-names = "bus";
> operating-points-v2 = <&bus_dmc_opp_table>;
> status = "disabled";
> };
>
> bus_dmc_opp_table: opp_table1 {
> compatible = "operating-points-v2";
> opp-shared;
>
> opp@50000000 {
> opp-hz = /bits/ 64 <50000000>;
> opp-microvolt = <800000>;
> };
> opp@100000000 {
> opp-hz = /bits/ 64 <100000000>;
> opp-microvolt = <800000>;
> };
> opp@134000000 {
> opp-hz = /bits/ 64 <134000000>;
> opp-microvolt = <800000>;
> };
> opp@200000000 {
> opp-hz = /bits/ 64 <200000000>;
> opp-microvolt = <825000>;
> };
> opp@400000000 {
> opp-hz = /bits/ 64 <400000000>;
> opp-microvolt = <875000>;
> };
> };
>
> - Usage case to handle the frequency and voltage of bus on runtime
> in exynos3250-rinato.dts are listed below:
>
> &bus_dmc {
> devfreq-events = <&ppmu_dmc0_3>, <&ppmu_dmc1_3>;
> vdd-supply = <&buck1_reg>; /* VDD_MIF */
> status = "okay";
> };
>
> 2. Add new passive governor of DEVFREQ framework (patch5-patch7)
> : This patch-set add the new passive governor for DEVFREQ framework.
> The existing governors (ondemand, performance and so on) are used for DVFS
> (Dynamic Voltage and Frequency Scaling) drivers. The existing governors
> are independently used for specific device driver which don't give the
> influence to other device drviers and also don't receive the effect from
> other device drivers.
>
> The passive governor depends on operation of parent driver with existing
> governors(ondemand, performance and so on) extremely and is not able to
> decide the new frequency by oneself. According to the decided new frequency
> of parent driver with governor, the passive governor uses it to decide
> the appropriate frequency for own device driver. The passive governor
> must need the following information from device tree:
>
> For exameple,
> There are one more bus device drivers in Exynos3250 which need to
> change their source clock according to their utilization on runtime.
> But, they share the same power line (e.g., regulator). So, LEFTBUS bus
> driver is operated as parent with ondemand governor and then the rest
> device driver with passive governor.
>
> The buses of Internal block in exynos3250.dtsi are listed below:
> When LEFTBUS bus driver (parent) changes the bus frequency with
> ondemand governor on runtime, the rest bus devices which sharing
> the same power line (VDD_INT) will change the each bus frequency
> according to the decision of LEFTBUS bus driver (parent).
>
> - INT (Internal) block
> : VDD_INT |--- LEFTBUS
> |--- PERIL
> |--- MFC
> |--- G3D
> |--- RIGHTBUS
> |--- FSYS
> |--- LCD0
> |--- PERIR
> |--- ISP
> |--- CAM
>
> - The buss of INT block in exynos3250.dtsi are listed below:
> bus_leftbus: bus_leftbus {
> compatible = "samsung,exynos-bus";
> clocks = <&cmu CLK_DIV_GDL>;
> clock-names = "bus";
> operating-points-v2 = <&bus_leftbus_opp_table>;
> status = "disabled";
> };
>
> bus_rightbus: bus_rightbus {
> compatible = "samsung,exynos-bus";
> clocks = <&cmu CLK_DIV_GDR>;
> clock-names = "bus";
> operating-points-v2 = <&bus_leftbus_opp_table>;
> status = "disabled";
> };
>
> (Omit the rest bus dt node)
>
> - Usage case to handle the frequency and voltage of bus on runtime
> in exynos3250-rinato.dts are listed below:
> /* Parent bus device of VDD_INT */
> &bus_leftbus {
> devfreq-events = <&ppmu_leftbus_3>, <&ppmu_rightbus_3>;
> vdd-supply = <&buck3_reg>;
> status = "okay";
> };
>
> /* Passive bus device depend on LEFTBUS bus. */
> &bus_rightbus {
> devfreq = <&bus_leftbus>; /* 'devfreq' property indicates
> the phandle of parent device. */
> status = "okay";
> };
>
> (Omit the rest bus dt node)
>
> Chanwoo Choi (20):
> PM / devfreq: exynos: Add generic exynos bus frequency driver
> PM / devfreq: exynos: Add documentation for generic exynos bus frequency driver
> ARM: dts: Add DMC bus node for Exynos3250
> ARM: dts: Add DMC bus frequency for exynos3250-rinato/monk
> PM / devfreq: Add new passive governor
> PM / devfreq: Add devfreq_get_devfreq_by_phandle()
> PM / devfreq: Show the related information according to governor type
> PM / devfreq: exynos: Add support of bus frequency of sub-blocks using passive governor
> PM / devfreq: exynos: Update documentation for bus devices using passive governor
> PM / devfreq: exynos: Add the detailed correlation between sub-blocks and power line
> PM / devfreq: exynos: Remove unused exynos4/5 busfreq driver
> MAINTAINERS: Add samsung bus frequency driver entry
> ARM: dts: Add bus nodes using VDD_INT for Exynos3250
> ARM: dts: Add bus nodes using VDD_MIF for Exynos4x12
> ARM: dts: Add bus nodes using VDD_INT for Exynos4x12
> ARM: dts: Add bus nodes using VDD_MIF for Exynos4210
> ARM: dts: Add exynos4412-ppmu-common dtsi to delete duplicate PPMU nodes
> ARM: dts: Add support of bus frequency using VDD_INT for exynos3250-rinato
> ARM: dts: Expand the voltage range of buck1/3 regulator for exynos4412-odroidu3
> ARM: dts: Add support of bus frequency for exynos4412-trats/odroidu3
>
> .../devicetree/bindings/devfreq/exynos-bus.txt | 388 +++++++
> MAINTAINERS | 9 +
> arch/arm/boot/dts/exynos3250-monk.dts | 47 +-
> arch/arm/boot/dts/exynos3250-rinato.dts | 88 +-
> arch/arm/boot/dts/exynos3250.dtsi | 181 ++++
> arch/arm/boot/dts/exynos4210.dtsi | 159 +++
> arch/arm/boot/dts/exynos4412-odroid-common.dtsi | 54 +-
> arch/arm/boot/dts/exynos4412-ppmu-common.dtsi | 50 +
> arch/arm/boot/dts/exynos4412-trats2.dts | 88 +-
> arch/arm/boot/dts/exynos4x12.dtsi | 174 ++++
> drivers/devfreq/Kconfig | 37 +-
> drivers/devfreq/Makefile | 2 +
> drivers/devfreq/devfreq.c | 120 ++-
> drivers/devfreq/exynos/Makefile | 3 +-
> drivers/devfreq/exynos/exynos-bus.c | 556 +++++++++++
> drivers/devfreq/exynos/exynos4_bus.c | 1055 --------------------
> drivers/devfreq/exynos/exynos4_bus.h | 110 --
> drivers/devfreq/exynos/exynos5_bus.c | 431 --------
> drivers/devfreq/exynos/exynos_ppmu.c | 119 ---
> drivers/devfreq/exynos/exynos_ppmu.h | 86 --
> drivers/devfreq/governor.h | 7 +
> drivers/devfreq/governor_passive.c | 109 ++
> drivers/devfreq/governor_performance.c | 1 +
> drivers/devfreq/governor_powersave.c | 1 +
> drivers/devfreq/governor_simpleondemand.c | 1 +
> drivers/devfreq/governor_userspace.c | 1 +
> include/linux/devfreq.h | 26 +
> 27 files changed, 1955 insertions(+), 1948 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> create mode 100644 arch/arm/boot/dts/exynos4412-ppmu-common.dtsi
> create mode 100644 drivers/devfreq/exynos/exynos-bus.c
> delete mode 100644 drivers/devfreq/exynos/exynos4_bus.c
> delete mode 100644 drivers/devfreq/exynos/exynos4_bus.h
> delete mode 100644 drivers/devfreq/exynos/exynos5_bus.c
> delete mode 100644 drivers/devfreq/exynos/exynos_ppmu.c
> delete mode 100644 drivers/devfreq/exynos/exynos_ppmu.h
> create mode 100644 drivers/devfreq/governor_passive.c
>

[ 3.041556] ===============================
[ 3.041560] [ INFO: suspicious RCU usage. ]
[ 3.041569] 4.5.0-rc4-debug+ #2 Tainted: G W
[ 3.041572] -------------------------------
[ 3.041578] drivers/base/power/opp/core.c:377 Missing rcu_read_lock() or dev_opp_list_lock protection!
[ 3.041580]
other info that might help us debug this:

[ 3.041586]
rcu_scheduler_active = 1, debug_locks = 0
[ 3.041592] 3 locks held by kworker/u8:3/861:
[ 3.041635] #0: ("%s"("devfreq_wq")){.+.+..}, at: [<c00463a0>] process_one_work+0x134/0x7ac
[ 3.041648] #1: ((&(&devfreq->work)->work)){+.+...}, at: [<c00463a0>] process_one_work+0x134/0x7ac
[ 3.041675] #2: (&devfreq->lock){+.+.+.}, at: [<c0470c98>] devfreq_monitor+0x24/0x80
[ 3.041678]
stack backtrace:
[ 3.041686] CPU: 1 PID: 861 Comm: kworker/u8:3 Tainted: G W 4.5.0-rc4-debug+ #2
[ 3.041688] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 3.041699] Workqueue: devfreq_wq devfreq_monitor
[ 3.041706] Backtrace:
[ 3.041736] [<c0014818>] (dump_backtrace) from [<c0014a14>] (show_stack+0x18/0x1c)
[ 3.041749] r6:c0845660 r5:60000053 r4:00000000 r3:dc8ba700
[ 3.041773] [<c00149fc>] (show_stack) from [<c0283f9c>] (dump_stack+0xb0/0xdc)
[ 3.041787] [<c0283eec>] (dump_stack) from [<c007435c>] (lockdep_rcu_suspicious+0xe8/0x11c)
[ 3.041800] r8:ee381ea8 r7:c0757330 r6:00000179 r5:c0757350 r4:ee098c80 r3:00000000
[ 3.041817] [<c0074274>] (lockdep_rcu_suspicious) from [<c0366bb4>] (dev_pm_opp_find_freq_ceil+0xe8/0x100)
[ 3.041827] r7:ee932a00 r6:c0865ac0 r5:eeb43410 r4:ee381e1c
[ 3.041835] [<c0366acc>] (dev_pm_opp_find_freq_ceil) from [<c0472928>] (devfreq_recommended_opp+0x3c/0x54)
[ 3.041845] r6:ee381e1c r5:eeb43410 r4:ee381e1c r3:03c1f399
[ 3.041852] [<c04728ec>] (devfreq_recommended_opp) from [<c0473568>] (devfreq_passive_get_target_freq+0xd8/0xfc)
[ 3.041858] r5:ee35e400 r4:ee35dc00
[ 3.041864] [<c0473490>] (devfreq_passive_get_target_freq) from [<c0470950>] (update_devfreq_passive+0x48/0x94)
[ 3.041875] r6:03c1f399 r5:ee35df3c r4:ee35e400 r3:c0473490
[ 3.041881] [<c0470908>] (update_devfreq_passive) from [<c0470b50>] (update_devfreq+0x12c/0x168)
[ 3.041889] r6:00000000 r5:ee35df3c r4:ee35dc00
[ 3.041895] [<c0470a24>] (update_devfreq) from [<c0470ca0>] (devfreq_monitor+0x2c/0x80)
[ 3.041904] r6:ee35dc00 r5:ee35dc08 r4:ee35deb4
[ 3.041910] [<c0470c74>] (devfreq_monitor) from [<c0046474>] (process_one_work+0x208/0x7ac)
[ 3.041920] r6:ee80ac00 r5:ee35deb4 r4:ee12d600 r3:c0470c74
[ 3.041925] [<c004626c>] (process_one_work) from [<c0046a64>] (worker_thread+0x4c/0x514)
[ 3.041938] r10:ee12d600 r9:ee380000 r8:c0822100 r7:ee80ac34 r6:00000088 r5:ee12d618
[ 3.041942] r4:ee80ac00
[ 3.041956] [<c0046a18>] (worker_thread) from [<c004d74c>] (kthread+0x108/0x120)
[ 3.041969] r10:00000000 r9:00000000 r8:00000000 r7:c0046a18 r6:ee12d600 r5:ee1ea340
[ 3.041973] r4:00000000
[ 3.041982] [<c004d644>] (kthread) from [<c000ff30>] (ret_from_fork+0x14/0x24)
[ 3.041992] r7:00000000 r6:00000000 r5:c004d644 r4:ee1ea340
[ 3.083806] devfreq bus_leftbus: Couldn't update frequency transition information.

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