Message-id: <569EDE4F.6020702@samsung.com>
Date:	Wed, 20 Jan 2016 10:09:35 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>,
	myungjoo.ham@...sung.com, k.kozlowski@...sung.com, kgene@...nel.org
Cc:	kyungmin.park@...sung.com, robh+dt@...nel.org, pawel.moll@....com,
	mark.rutland@....com, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, linux@....linux.org.uk,
	linux.amoon@...il.com, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v4 00/20] PM / devferq: Add generic exynos bus frequency
 driver and new passive governor

Hi Tobias,

On 2016년 01월 19일 18:13, Tobias Jakobi wrote:
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> Hello,
> 
> I've tested this on my Odroid-X2 but ran into issues. Patch 08/20
> introduces some pr_info() to exynos_bus_probe().
> 
> In my case both max_state and freq_table are zero though, so getting
> {min,max}_freq triggers an kernel oops. If I just remove the code the
> drivers probes correctly.

Thanks for your test. If you ok, could you give me a kernel oops message?
It is helpful to remove the corner case of this driver.

Best Regards,
Chanwoo Choi

> 
> 
> 
> 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@...00000 { opp-hz = /bits/ 64 <50000000>; opp-microvolt =
>> <800000>; }; opp@...000000 { opp-hz = /bits/ 64 <100000000>; 
>> opp-microvolt = <800000>; }; opp@...000000 { opp-hz = /bits/ 64
>> <134000000>; opp-microvolt = <800000>; }; opp@...000000 { opp-hz =
>> /bits/ 64 <200000000>; opp-microvolt = <825000>; }; opp@...000000
>> { 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
>>
> 
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