Re: [PATCH v2 00/19] PM / devferq: Add generic exynos bus frequency driver and new passive governor

2015-12-09 Thread Anand Moon 
Hi Chanwoo Choi,

On 9 December 2015 at 09:37, 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[1]
> with the similiar concept. This is is revised version for exynos bus 
> frequency.
> - Generic exynos bus frequency driver
> - New passive governor of DEVFREQ framework
>
> Depends on:
> - This patch-set is based on devfreq.git[2].
> [1] https://lkml.org/lkml/2015/1/7/872
>: [PATCHv3 0/8] devfreq: Add generic exynos memory-bus frequency driver
> [2] https://git.kernel.org/cgit/linux/kernel/git/mzx/devfreq.git/ (branch: 
> for-rafael)
>
> 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 = <_dmc CLK_DIV_DMC>;
> clock-names = "bus";
> operating-points-v2 = <_dmc_opp_table>;
> status = "disabled";
> };
>
> bus_dmc_opp_table: opp_table0 {
> compatible = "operating-points-v2";
> opp-shared;
>
> opp00 {
> opp-hz = /bits/ 64 <5000>;
> opp-microvolt = <80>;
> };
> opp01 {
> opp-hz = /bits/ 64 <1>;
> opp-microvolt = <80>;
> };
> opp02 {
> opp-hz = /bits/ 64 <13400>;
> opp-microvolt = <80>;
> };
> opp03 {
> opp-hz = /bits/ 64 <2>;
> opp-microvolt = <80>;
> };
> opp04 {
> opp-hz = /bits/ 64 <4>;
> opp-microvolt = <875000>;
> };
> };
>
> - Usage case to handle the frequency and voltage of bus on runtime
>   in exynos3250-rinato.dts are listed below:
>
> _dmc {
> devfreq-events = <_dmc0_3>, <_dmc1_3>;
> vdd-supply = <_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

Re: [PATCH v2 00/19] PM / devferq: Add generic exynos bus frequency driver and new passive governor

2015-12-09 Thread Krzysztof Kozlowski 
On 09.12.2015 13:07, Chanwoo Choi wrote:

(...)

>  .../devicetree/bindings/devfreq/exynos-bus.txt |  383 +++

How about adding this file to the MAINTAINERS to devfreq exynos entry?
Unfortunately, in current linux-next, I can find the entry for devfreq
exynos. However I saw patches adding such entries... aren't they merged
to linux-next?

Best regards,
Krzysztof

>  arch/arm/boot/dts/exynos3250-monk.dts  |6 +
>  arch/arm/boot/dts/exynos3250-rinato.dts|   47 +
>  arch/arm/boot/dts/exynos3250.dtsi  |  194 
>  arch/arm/boot/dts/exynos4210.dtsi  |  172 
>  arch/arm/boot/dts/exynos4412-odroid-common.dtsi|   93 +-
>  arch/arm/boot/dts/exynos4412-trats2.dts|   47 +
>  arch/arm/boot/dts/exynos4x12.dtsi  |  184 
>  drivers/devfreq/Kconfig|   37 +-
>  drivers/devfreq/Makefile   |2 +
>  drivers/devfreq/devfreq.c  |  120 ++-
>  drivers/devfreq/exynos/Makefile|3 +-
>  drivers/devfreq/exynos/exynos-bus.c|  549 ++
>  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|   28 +
>  25 files changed, 1958 insertions(+), 1828 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/devfreq/exynos-bus.txt
>  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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Re: [PATCH v2 00/19] PM / devferq: Add generic exynos bus frequency driver and new passive governor

2015-12-09 Thread Chanwoo Choi 
On 2015년 12월 10일 10:22, Krzysztof Kozlowski wrote:
> On 10.12.2015 09:57, Krzysztof Kozlowski wrote:
>> On 09.12.2015 13:07, Chanwoo Choi wrote:
>>
>> (...)
>>
>>>  .../devicetree/bindings/devfreq/exynos-bus.txt |  383 +++
>>
>> How about adding this file to the MAINTAINERS to devfreq exynos entry?

OK. I'll add new entry for 'devfreq exynos' as following:
 
+SAMSUNG BUS DEVICE FREQUENCY SUPPORT
+M: Chanwoo Choi 
+L: linux...@vger.kernel.org
+L: linux-samsung-soc@vger.kernel.org
+T: git git://git.kernel.org/pub/scm/linux/kernel/git/mzx/devfreq.git
+S: Supported
+F: drivers/devfreq/exynos/exynos-bus.c
+F: Documentation/devicetree/bindings/devfreq/exynos-bus.txt

>> Unfortunately, in current linux-next, I can find the entry for devfreq
> 
> D'oh! I meant:^ I cannot find the entry for...
> 
> BR,
> Krzysztof
> 
>> exynos. However I saw patches adding such entries... aren't they merged
>> to linux-next?

Yes, it is not merged to linux-next because any git repository
don't apply this patchset. To merge the devfreq patchset to linux-next,
devfreq maintainer should send the request mail to Stephen Rothwell.

[snip]

Best Regards,
Chanwoo Choi
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Re: [PATCH v2 00/19] PM / devferq: Add generic exynos bus frequency driver and new passive governor

2015-12-09 Thread Krzysztof Kozlowski 
On 10.12.2015 09:57, Krzysztof Kozlowski wrote:
> On 09.12.2015 13:07, Chanwoo Choi wrote:
> 
> (...)
> 
>>  .../devicetree/bindings/devfreq/exynos-bus.txt |  383 +++
> 
> How about adding this file to the MAINTAINERS to devfreq exynos entry?
> Unfortunately, in current linux-next, I can find the entry for devfreq

D'oh! I meant:^ I cannot find the entry for...

BR,
Krzysztof

> exynos. However I saw patches adding such entries... aren't they merged
> to linux-next?
> 
> Best regards,
> Krzysztof
> 
>>  arch/arm/boot/dts/exynos3250-monk.dts  |6 +
>>  arch/arm/boot/dts/exynos3250-rinato.dts|   47 +
>>  arch/arm/boot/dts/exynos3250.dtsi  |  194 
>>  arch/arm/boot/dts/exynos4210.dtsi  |  172 
>>  arch/arm/boot/dts/exynos4412-odroid-common.dtsi|   93 +-
>>  arch/arm/boot/dts/exynos4412-trats2.dts|   47 +
>>  arch/arm/boot/dts/exynos4x12.dtsi  |  184 
>>  drivers/devfreq/Kconfig|   37 +-
>>  drivers/devfreq/Makefile   |2 +
>>  drivers/devfreq/devfreq.c  |  120 ++-
>>  drivers/devfreq/exynos/Makefile|3 +-
>>  drivers/devfreq/exynos/exynos-bus.c|  549 ++
>>  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|   28 +
>>  25 files changed, 1958 insertions(+), 1828 deletions(-)
>>  create mode 100644 Documentation/devicetree/bindings/devfreq/exynos-bus.txt
>>  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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Re: [PATCH v2 00/19] PM / devferq: Add generic exynos bus frequency driver and new passive governor

2015-12-09 Thread Chanwoo Choi 
Hi Anand,

First of all, thanks for trying to test this series.

On 2015년 12월 10일 04:05, Anand Moon wrote:
> Hi Chanwoo Choi,
> 
> On 9 December 2015 at 09:37, 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[1]
>> with the similiar concept. This is is revised version for exynos bus 
>> frequency.
>> - Generic exynos bus frequency driver
>> - New passive governor of DEVFREQ framework
>>
>> Depends on:
>> - This patch-set is based on devfreq.git[2].
>> [1] https://lkml.org/lkml/2015/1/7/872
>>: [PATCHv3 0/8] devfreq: Add generic exynos memory-bus frequency driver
>> [2] https://git.kernel.org/cgit/linux/kernel/git/mzx/devfreq.git/ (branch: 
>> for-rafael)
>>
>> 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 = <_dmc CLK_DIV_DMC>;
>> clock-names = "bus";
>> operating-points-v2 = <_dmc_opp_table>;
>> status = "disabled";
>> };
>>
>> bus_dmc_opp_table: opp_table0 {
>> compatible = "operating-points-v2";
>> opp-shared;
>>
>> opp00 {
>> opp-hz = /bits/ 64 <5000>;
>> opp-microvolt = <80>;
>> };
>> opp01 {
>> opp-hz = /bits/ 64 <1>;
>> opp-microvolt = <80>;
>> };
>> opp02 {
>> opp-hz = /bits/ 64 <13400>;
>> opp-microvolt = <80>;
>> };
>> opp03 {
>> opp-hz = /bits/ 64 <2>;
>> opp-microvolt = <80>;
>> };
>> opp04 {
>> opp-hz = /bits/ 64 <4>;
>> opp-microvolt = <875000>;
>> };
>> };
>>
>> - Usage case to handle the frequency and voltage of bus on runtime
>>   in exynos3250-rinato.dts are listed below:
>>
>> _dmc {
>> devfreq-events = <_dmc0_3>, <_dmc1_3>;
>> vdd-supply = <_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

Re: [PATCH v2 00/19] PM / devferq: Add generic exynos bus frequency driver and new passive governor

2015-12-09 Thread Chanwoo Choi 
Hi Anand,

On 2015년 12월 10일 13:14, Anand Moon wrote:
> Hi Chanwoo Choi,
> 
> On 10 December 2015 at 05:42, Chanwoo Choi  wrote:
>> Hi Anand,
>>
>> First of all, thanks for trying to test this series.
>>
>> On 2015년 12월 10일 04:05, Anand Moon wrote:
>>> Hi Chanwoo Choi,
>>>
>>> On 9 December 2015 at 09:37, 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[1]
 with the similiar concept. This is is revised version for exynos bus 
 frequency.
 - Generic exynos bus frequency driver
 - New passive governor of DEVFREQ framework

 Depends on:
 - This patch-set is based on devfreq.git[2].
 [1] https://lkml.org/lkml/2015/1/7/872
: [PATCHv3 0/8] devfreq: Add generic exynos memory-bus frequency driver
 [2] https://git.kernel.org/cgit/linux/kernel/git/mzx/devfreq.git/ (branch: 
 for-rafael)

 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 = <_dmc CLK_DIV_DMC>;
 clock-names = "bus";
 operating-points-v2 = <_dmc_opp_table>;
 status = "disabled";
 };

 bus_dmc_opp_table: opp_table0 {
 compatible = "operating-points-v2";
 opp-shared;

 opp00 {
 opp-hz = /bits/ 64 <5000>;
 opp-microvolt = <80>;
 };
 opp01 {
 opp-hz = /bits/ 64 <1>;
 opp-microvolt = <80>;
 };
 opp02 {
 opp-hz = /bits/ 64 <13400>;
 opp-microvolt = <80>;
 };
 opp03 {
 opp-hz = /bits/ 64 <2>;
 opp-microvolt = <80>;
 };
 opp04 {
 opp-hz = /bits/ 64 <4>;
 opp-microvolt = <875000>;
 };
 };

 - Usage case to handle the frequency and voltage of bus on runtime
   in exynos3250-rinato.dts are listed below:

 _dmc {
 devfreq-events = <_dmc0_3>, <_dmc1_3>;
 vdd-supply = <_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

Re: [PATCH v2 00/19] PM / devferq: Add generic exynos bus frequency driver and new passive governor

2015-12-09 Thread Anand Moon 
Hi Chanwoo Choi,

On 10 December 2015 at 05:42, Chanwoo Choi  wrote:
> Hi Anand,
>
> First of all, thanks for trying to test this series.
>
> On 2015년 12월 10일 04:05, Anand Moon wrote:
>> Hi Chanwoo Choi,
>>
>> On 9 December 2015 at 09:37, 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[1]
>>> with the similiar concept. This is is revised version for exynos bus 
>>> frequency.
>>> - Generic exynos bus frequency driver
>>> - New passive governor of DEVFREQ framework
>>>
>>> Depends on:
>>> - This patch-set is based on devfreq.git[2].
>>> [1] https://lkml.org/lkml/2015/1/7/872
>>>: [PATCHv3 0/8] devfreq: Add generic exynos memory-bus frequency driver
>>> [2] https://git.kernel.org/cgit/linux/kernel/git/mzx/devfreq.git/ (branch: 
>>> for-rafael)
>>>
>>> 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 = <_dmc CLK_DIV_DMC>;
>>> clock-names = "bus";
>>> operating-points-v2 = <_dmc_opp_table>;
>>> status = "disabled";
>>> };
>>>
>>> bus_dmc_opp_table: opp_table0 {
>>> compatible = "operating-points-v2";
>>> opp-shared;
>>>
>>> opp00 {
>>> opp-hz = /bits/ 64 <5000>;
>>> opp-microvolt = <80>;
>>> };
>>> opp01 {
>>> opp-hz = /bits/ 64 <1>;
>>> opp-microvolt = <80>;
>>> };
>>> opp02 {
>>> opp-hz = /bits/ 64 <13400>;
>>> opp-microvolt = <80>;
>>> };
>>> opp03 {
>>> opp-hz = /bits/ 64 <2>;
>>> opp-microvolt = <80>;
>>> };
>>> opp04 {
>>> opp-hz = /bits/ 64 <4>;
>>> opp-microvolt = <875000>;
>>> };
>>> };
>>>
>>> - Usage case to handle the frequency and voltage of bus on runtime
>>>   in exynos3250-rinato.dts are listed below:
>>>
>>> _dmc {
>>> devfreq-events = <_dmc0_3>, <_dmc1_3>;
>>> vdd-supply = <_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