Date:	Fri, 22 Jan 2016 12:01:30 +0100
From:	Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>
To:	Chanwoo Choi <cw00.choi@...sung.com>,
	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

Hey Chanwoo,


Chanwoo Choi wrote:
> Hi Tobias,
> 
> On 2016년 01월 19일 18:13, Tobias Jakobi wrote:
> 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.
sure, I've sttached the kernel oops.

- Tobias


>> 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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