[GIT PULL 0/3] ARM: exynos: Second round of stuff for v4.9

[GIT PULL 0/3] ARM: exynos: Second round of stuff for v4.9

[Krzysztof Kozlowski]

From: Krzysztof Kozlowski <k.kozlowski@samsung.com>

Hi,

I know it is late but it is not a big pull request. Mostly DT cleanup.
One change touching clocksource was acked by Daniel Lezcano (he
mentioned it can go through arm-soc).

Some stuff moved into topic branch. No conflicts expected, no specific
order of pulling.

Best regards,
Krzysztof

[GIT PULL 1/3] ARM: soc: exynos: Drivers for v4.9

[Krzysztof Kozlowski]

From: Krzysztof Kozlowski <k.kozlowski@samsung.com>

Hi,

Drivers related changes.


Best regards,
Krzysztof


The following changes since commit 29b4817d4018df78086157ea3a55c1d9424a7cfc:

  Linux 4.8-rc1 (2016-08-07 18:18:00 -0700)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux.git tags/samsung-drivers-4.9-2

for you to fetch changes up to 8bc6bf178b671eb9b9fa806804f3990cb4c332aa:

  dt-bindings: EXYNOS: Add Exynos5433 PMU compatible (2016-09-16 13:21:04 +0200)

----------------------------------------------------------------
Samsung drivers/soc update for v4.9:
1. Allow compile testing of exynos-mct clocksource driver on ARM64.
2. Document Exynos5433 PMU compatible (already used by clkout driver and more
   will be coming soon).

----------------------------------------------------------------
Chanwoo Choi (2):
      clocksource: exynos_mct: Add the support for ARM64
      dt-bindings: EXYNOS: Add Exynos5433 PMU compatible

 Documentation/devicetree/bindings/arm/samsung/pmu.txt | 1 +
 drivers/clocksource/Kconfig                           | 2 +-
 drivers/clocksource/exynos_mct.c                      | 4 ++++
 3 files changed, 6 insertions(+), 1 deletion(-)

[GIT PULL 2/3] ARM: dts: exynos: DT for v4.9, second round

[Krzysztof Kozlowski]

From: Krzysztof Kozlowski <k.kozlowski@samsung.com>


The following changes since commit 05b01dd936b46f2c3cfbb10bc89c0ec79c745e5d:

  ARM: dts: exynos: Use 'hpd-gpios' instead of 'hpd-gpio' (2016-08-24 21:09:24 +0200)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux.git tags/samsung-dt-4.9-2

for you to fetch changes up to 5271d002709e8ca27232ab031f35e0df1d0fe4ed:

  ARM: dts: s5p: Add missing unit name to memory nodes for S5PV210 boards (2016-09-16 09:17:00 +0200)

----------------------------------------------------------------
Samsung DeviceTree update for v4.9, second round:
1. Enable HDMI on Arndale Octa board.
2. Update list of clocks for FIMC-IS block on Exynos4x12.
3. Remove skeleton.dtsi thus fixing DT compiler warning:
	"Node /memory has a reg or ranges property, but no unit name"
   This is a tree-wide effort by various people. Javier Martinez Canillas did
   it for Exynos and S5PV210.

----------------------------------------------------------------
Javier Martinez Canillas (9):
      ARM: dts: exynos: Add missing memory node for Exynos5440 boards
      ARM: dts: exynos: Remove skeleton.dtsi usage for Exynos3
      ARM: dts: exynos: Remove skeleton.dtsi usage for Exynos4
      ARM: dts: exynos: Remove skeleton.dtsi usage for Exynos5
      ARM: dts: exynos: Add missing unit name to memory nodes in Exynos3 DTS
      ARM: dts: exynos: Add missing unit name to memory nodes in Exynos4 DTS
      ARM: dts: exynos: Add missing unit name to memory nodes in Exynos5 DTS
      ARM: dts: s5p: Remove skeleton.dtsi inclusion for S5PV210
      ARM: dts: s5p: Add missing unit name to memory nodes for S5PV210 boards

Marek Szyprowski (1):
      ARM: dts: exynos: Add all required FIMC-IS clocks to exynos4x12

Milo Kim (1):
      ARM: dts: exynos: Enable HDMI for Arndale Octa board

 arch/arm/boot/dts/exynos3250-artik5.dtsi           |  3 ++-
 arch/arm/boot/dts/exynos3250-monk.dts              |  3 ++-
 arch/arm/boot/dts/exynos3250-rinato.dts            |  3 ++-
 arch/arm/boot/dts/exynos3250.dtsi                  |  3 ++-
 arch/arm/boot/dts/exynos4.dtsi                     |  3 ++-
 arch/arm/boot/dts/exynos4210-origen.dts            |  3 ++-
 arch/arm/boot/dts/exynos4210-smdkv310.dts          |  3 ++-
 arch/arm/boot/dts/exynos4210-trats.dts             |  3 ++-
 arch/arm/boot/dts/exynos4210-universal_c210.dts    |  3 ++-
 arch/arm/boot/dts/exynos4412-odroidu3.dts          |  3 ++-
 arch/arm/boot/dts/exynos4412-odroidx.dts           |  3 ++-
 arch/arm/boot/dts/exynos4412-odroidx2.dts          |  3 ++-
 arch/arm/boot/dts/exynos4412-origen.dts            |  3 ++-
 arch/arm/boot/dts/exynos4412-smdk4412.dts          |  3 ++-
 arch/arm/boot/dts/exynos4412-tiny4412.dts          |  3 ++-
 arch/arm/boot/dts/exynos4412-trats2.dts            |  3 ++-
 arch/arm/boot/dts/exynos4415.dtsi                  |  3 ++-
 arch/arm/boot/dts/exynos4x12.dtsi                  |  5 ++++-
 arch/arm/boot/dts/exynos5.dtsi                     |  3 ++-
 arch/arm/boot/dts/exynos5250-arndale.dts           |  3 ++-
 arch/arm/boot/dts/exynos5250-smdk5250.dts          |  3 ++-
 arch/arm/boot/dts/exynos5250-snow-common.dtsi      |  3 ++-
 arch/arm/boot/dts/exynos5250-spring.dts            |  3 ++-
 arch/arm/boot/dts/exynos5260-xyref5260.dts         |  3 ++-
 arch/arm/boot/dts/exynos5260.dtsi                  |  4 ++--
 arch/arm/boot/dts/exynos5410-odroidxu.dts          |  3 ++-
 arch/arm/boot/dts/exynos5410-smdk5410.dts          |  3 ++-
 arch/arm/boot/dts/exynos5420-arndale-octa.dts      | 16 +++++++++++++++-
 arch/arm/boot/dts/exynos5420-peach-pit.dts         |  3 ++-
 arch/arm/boot/dts/exynos5420-smdk5420.dts          |  3 ++-
 arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi |  3 ++-
 arch/arm/boot/dts/exynos5440-sd5v1.dts             |  6 ++++++
 arch/arm/boot/dts/exynos5440-ssdk5440.dts          |  6 ++++++
 arch/arm/boot/dts/exynos5440.dtsi                  |  3 ++-
 arch/arm/boot/dts/exynos54xx.dtsi                  |  1 -
 arch/arm/boot/dts/exynos5800-peach-pi.dts          |  3 ++-
 arch/arm/boot/dts/s5pv210-aquila.dts               |  2 +-
 arch/arm/boot/dts/s5pv210-goni.dts                 |  2 +-
 arch/arm/boot/dts/s5pv210-smdkc110.dts             |  2 +-
 arch/arm/boot/dts/s5pv210-smdkv210.dts             |  2 +-
 arch/arm/boot/dts/s5pv210-torbreck.dts             |  2 +-
 arch/arm/boot/dts/s5pv210.dtsi                     |  4 +++-
 42 files changed, 101 insertions(+), 41 deletions(-)

[GIT PULL 3/3] ARM: dts: exynos: pinctrl cleanup for v4.9

[Krzysztof Kozlowski]

From: Krzysztof Kozlowski <k.kozlowski@samsung.com>

Hi,

A separate topic branch with DT cleanup.


Best regards,
Krzysztof


The following changes since commit 29b4817d4018df78086157ea3a55c1d9424a7cfc:

  Linux 4.8-rc1 (2016-08-07 18:18:00 -0700)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux.git tags/samsung-dt-pinctrl-4.9

for you to fetch changes up to d13799237dee34e1b9cd377f0ced7bee24ac810f:

  ARM: dts: s3c64xx: Use macros for pinctrl configuration (2016-09-16 13:32:27 +0200)

----------------------------------------------------------------
Topic branch for Samsung DeviceTree cleanup for 4.9.

Replace in DT sources hard-coded values for pinctrl configuration like pull
up/down, drive strength and function. This makes the DTS easier to read,
especially that some drive strengths values are quite non-obvious.

----------------------------------------------------------------
Krzysztof Kozlowski (17):
      pinctrl: dt-bindings: samsung: Add header with values used for configuration
      pinctrl: dt-bindings: samsung: Update documentation with new macros
      ARM: dts: exynos: Use common macros for pinctrl configuration
      ARM: dts: exynos: Use macros for pinctrl configuration on exynos3250
      ARM: dts: exynos: Use macros for pinctrl configuration on exynos4210
      ARM: dts: exynos: Use macros for pinctrl configuration on exynos4x12
      ARM: dts: exynos: Use macros for pinctrl configuration on exynos4415
      ARM: dts: exynos: Use macros for pinctrl configuration on exynos5250
      ARM: dts: exynos: Use macros for pinctrl configuration on exynos5260
      ARM: dts: exynos: Use macros for pinctrl configuration on exynos5410
      ARM: dts: exynos: Use macros for pinctrl configuration on exynos542x/exynos5800
      ARM: dts: exynos: Fix mismatched value for SD4 pull up/down configuration on exynos4210
      ARM: dts: exynos: Fix mismatched values of SD drive strengh configuration on exynos4415
      ARM: dts: s3c64xx: Use common macros for pinctrl configuration
      ARM: dts: s5pv210: Use macros for pinctrl configuration
      ARM: dts: s3c2416: Use macros for pinctrl configuration
      ARM: dts: s3c64xx: Use macros for pinctrl configuration

 .../bindings/pinctrl/samsung-pinctrl.txt           |  44 +-
 MAINTAINERS                                        |   2 +
 arch/arm/boot/dts/exynos3250-pinctrl.dtsi          | 346 +++++++-------
 arch/arm/boot/dts/exynos4210-pinctrl.dtsi          | 458 +++++++++---------
 arch/arm/boot/dts/exynos4210-smdkv310.dts          |  12 +-
 arch/arm/boot/dts/exynos4210-universal_c210.dts    |   8 +-
 arch/arm/boot/dts/exynos4412-odroid-common.dtsi    |  14 +-
 arch/arm/boot/dts/exynos4412-odroidx.dts           |   2 +-
 arch/arm/boot/dts/exynos4412-origen.dts            |  12 +-
 arch/arm/boot/dts/exynos4412-smdk4412.dts          |  12 +-
 arch/arm/boot/dts/exynos4415-pinctrl.dtsi          | 296 ++++++------
 arch/arm/boot/dts/exynos4x12-pinctrl.dtsi          | 525 ++++++++++-----------
 arch/arm/boot/dts/exynos5250-pinctrl.dtsi          | 404 ++++++++--------
 arch/arm/boot/dts/exynos5250-smdk5250.dts          |   6 +-
 arch/arm/boot/dts/exynos5250-snow-common.dtsi      |  76 +--
 arch/arm/boot/dts/exynos5250-snow-rev5.dts         |   6 +-
 arch/arm/boot/dts/exynos5250-snow.dts              |   6 +-
 arch/arm/boot/dts/exynos5250-spring.dts            |  72 +--
 arch/arm/boot/dts/exynos5260-pinctrl.dtsi          | 280 ++++++-----
 arch/arm/boot/dts/exynos5260-xyref5260.dts         |   6 +-
 arch/arm/boot/dts/exynos5410-odroidxu.dts          |  30 +-
 arch/arm/boot/dts/exynos5410-pinctrl.dtsi          | 182 +++----
 arch/arm/boot/dts/exynos5410-smdk5410.dts          |  10 +-
 arch/arm/boot/dts/exynos5420-arndale-octa.dts      |   6 +-
 arch/arm/boot/dts/exynos5420-peach-pit.dts         | 126 ++---
 arch/arm/boot/dts/exynos5420-pinctrl.dtsi          | 356 +++++++-------
 arch/arm/boot/dts/exynos5420-smdk5420.dts          |  18 +-
 arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi |  18 +-
 arch/arm/boot/dts/exynos5800-peach-pi.dts          | 126 ++---
 arch/arm/boot/dts/s3c2416-pinctrl.dtsi             |  38 +-
 arch/arm/boot/dts/s3c6410-mini6410.dts             |   4 +-
 arch/arm/boot/dts/s3c64xx-pinctrl.dtsi             | 356 +++++++-------
 arch/arm/boot/dts/s5pv210-aquila.dts               |   4 +-
 arch/arm/boot/dts/s5pv210-pinctrl.dtsi             | 476 +++++++++----------
 include/dt-bindings/pinctrl/samsung.h              |  57 +++
 35 files changed, 2223 insertions(+), 2171 deletions(-)
 create mode 100644 include/dt-bindings/pinctrl/samsung.h

Re: [GIT PULL 1/3] ARM: soc: exynos: Drivers for v4.9

[Arnd Bergmann]

On Sunday, September 18, 2016 6:39:46 PM CEST Krzysztof Kozlowski wrote:
> Samsung drivers/soc update for v4.9:
> 1. Allow compile testing of exynos-mct clocksource driver on ARM64.
> 2. Document Exynos5433 PMU compatible (already used by clkout driver and more
>    will be coming soon).

Pulled into next/drivers, thanks

Just for my understanding: why do we need the exynos-mct driver on ARM64
but not the delay-timer portion of it?

Is there an advantage in using MCT over the architected timer on these
chips? If so, should we also have a way to use it as the delay timer?

	Arnd

Re: [GIT PULL 2/3] ARM: dts: exynos: DT for v4.9, second round

[Arnd Bergmann]

On Sunday, September 18, 2016 6:39:47 PM CEST Krzysztof Kozlowski wrote:
> Samsung DeviceTree update for v4.9, second round:
> 1. Enable HDMI on Arndale Octa board.
> 2. Update list of clocks for FIMC-IS block on Exynos4x12.
> 3. Remove skeleton.dtsi thus fixing DT compiler warning:
>         "Node /memory has a reg or ranges property, but no unit name"
>    This is a tree-wide effort by various people. Javier Martinez Canillas did
>    it for Exynos and S5PV210.
> 

Pulled into next/dt, thanks!

	Arnd

Re: [GIT PULL 3/3] ARM: dts: exynos: pinctrl cleanup for v4.9

[Arnd Bergmann]

On Sunday, September 18, 2016 6:39:48 PM CEST Krzysztof Kozlowski wrote:
> Topic branch for Samsung DeviceTree cleanup for 4.9.
> 
> Replace in DT sources hard-coded values for pinctrl configuration like pull
> up/down, drive strength and function. This makes the DTS easier to read,
> especially that some drive strengths values are quite non-obvious.
> 
> 

Pulled into next/dt, thanks!

	Arnd

Re: [GIT PULL 1/3] ARM: soc: exynos: Drivers for v4.9

[Krzysztof Kozlowski]

On Mon, Sep 19, 2016 at 05:02:40PM +0200, Arnd Bergmann wrote:
> On Sunday, September 18, 2016 6:39:46 PM CEST Krzysztof Kozlowski wrote:
> > Samsung drivers/soc update for v4.9:
> > 1. Allow compile testing of exynos-mct clocksource driver on ARM64.
> > 2. Document Exynos5433 PMU compatible (already used by clkout driver and more
> >    will be coming soon).
> 
> Pulled into next/drivers, thanks
> 
> Just for my understanding: why do we need the exynos-mct driver on ARM64
> but not the delay-timer portion of it?

I think we want all of it but Doug's optimization 3252a646aa2c
("clocksource: exynos_mct: Only use 32-bits where possible") is not
ARM64 friendly. One way of dealing with it would be to prepare two
versions of exynos4_read_current_timer(). One reading only lower 32-bit
value for ARMv7 and second (slow) reading lower and upper for ARMv8.

> 
> Is there an advantage in using MCT over the architected timer on these
> chips? If so, should we also have a way to use it as the delay timer?

No, there is no real advantage... except that the SoC has some
interesting "characteristics"... The timers are tightly coupled. Very
tightly. I spent a lot of time and failed to boot my ARMv8 board without
some MCT magic.

Best regards,
Krzysztof

Re: [GIT PULL 1/3] ARM: soc: exynos: Drivers for v4.9

[Olof Johansson]

On Mon, Sep 19, 2016 at 8:53 AM, Krzysztof Kozlowski <krzk@kernel.org> wrote:
> On Mon, Sep 19, 2016 at 05:02:40PM +0200, Arnd Bergmann wrote:
>> On Sunday, September 18, 2016 6:39:46 PM CEST Krzysztof Kozlowski wrote:
>> > Samsung drivers/soc update for v4.9:
>> > 1. Allow compile testing of exynos-mct clocksource driver on ARM64.
>> > 2. Document Exynos5433 PMU compatible (already used by clkout driver and more
>> >    will be coming soon).
>>
>> Pulled into next/drivers, thanks
>>
>> Just for my understanding: why do we need the exynos-mct driver on ARM64
>> but not the delay-timer portion of it?
>
> I think we want all of it but Doug's optimization 3252a646aa2c
> ("clocksource: exynos_mct: Only use 32-bits where possible") is not
> ARM64 friendly. One way of dealing with it would be to prepare two
> versions of exynos4_read_current_timer(). One reading only lower 32-bit
> value for ARMv7 and second (slow) reading lower and upper for ARMv8.
>
>>
>> Is there an advantage in using MCT over the architected timer on these
>> chips? If so, should we also have a way to use it as the delay timer?
>
> No, there is no real advantage... except that the SoC has some
> interesting "characteristics"... The timers are tightly coupled. Very
> tightly. I spent a lot of time and failed to boot my ARMv8 board without
> some MCT magic.

What kind of magic is that? I can understand that needing the MCT for
some system-level timer functionality might be true (wakeups, etc),
but for system timesource avoiding the MMIO timer and using the arch
ones is a substantial performance improvement for gettimeofday() and
friends.

There was extensive discussion last year over using arch timers on
5420/5422, and it fizzled out with vague comments about something not
working right between A15/A7 on b.L. hardware. I'm presuming whatever
implementation details of that SoC has since been fixed on later chips
(including v8). Any chance you can confirm? It'd be very nice to leave
MCT behind on v8 as a system time source.


-Olof

Re: [GIT PULL 1/3] ARM: soc: exynos: Drivers for v4.9

[Krzysztof Kozlowski]

On Sun, Oct 02, 2016 at 05:25:07PM -0700, Olof Johansson wrote:
> On Mon, Sep 19, 2016 at 8:53 AM, Krzysztof Kozlowski <krzk@kernel.org> wrote:
> > On Mon, Sep 19, 2016 at 05:02:40PM +0200, Arnd Bergmann wrote:
> >> On Sunday, September 18, 2016 6:39:46 PM CEST Krzysztof Kozlowski wrote:
> >> > Samsung drivers/soc update for v4.9:
> >> > 1. Allow compile testing of exynos-mct clocksource driver on ARM64.
> >> > 2. Document Exynos5433 PMU compatible (already used by clkout driver and more
> >> >    will be coming soon).
> >>
> >> Pulled into next/drivers, thanks
> >>
> >> Just for my understanding: why do we need the exynos-mct driver on ARM64
> >> but not the delay-timer portion of it?
> >
> > I think we want all of it but Doug's optimization 3252a646aa2c
> > ("clocksource: exynos_mct: Only use 32-bits where possible") is not
> > ARM64 friendly. One way of dealing with it would be to prepare two
> > versions of exynos4_read_current_timer(). One reading only lower 32-bit
> > value for ARMv7 and second (slow) reading lower and upper for ARMv8.
> >
> >>
> >> Is there an advantage in using MCT over the architected timer on these
> >> chips? If so, should we also have a way to use it as the delay timer?
> >
> > No, there is no real advantage... except that the SoC has some
> > interesting "characteristics"... The timers are tightly coupled. Very
> > tightly. I spent a lot of time and failed to boot my ARMv8 board without
> > some MCT magic.
> 
> What kind of magic is that?

Most notably: the arch timer starts when MCT forward running counter
starts. Without kicking MCT, the arch timer seems to be frozen.

> I can understand that needing the MCT for
> some system-level timer functionality might be true (wakeups, etc),
> but for system timesource avoiding the MMIO timer and using the arch
> ones is a substantial performance improvement for gettimeofday() and
> friends.
> 
> There was extensive discussion last year over using arch timers on
> 5420/5422, and it fizzled out with vague comments about something not
> working right between A15/A7 on b.L. hardware. I'm presuming whatever
> implementation details of that SoC has since been fixed on later chips
> (including v8). Any chance you can confirm? It'd be very nice to leave
> MCT behind on v8 as a system time source.

Unfortunately, I cannot confirm this, at least on Exynos5433 (ARMv8). I
played with arch and MCT timers on it and failed to get the
arch-timer-only setup working. I did not have access to newer Exynos
designs (Exynos 7) so I do not know how it works there.

Best regards,
Krzysztof

Re: [GIT PULL 1/3] ARM: soc: exynos: Drivers for v4.9

[Kukjin Kim]

2016. 10. 3. 15:48 Krzysztof Kozlowski <krzk@kernel.org> wrote:

>> On Sun, Oct 02, 2016 at 05:25:07PM -0700, Olof Johansson wrote:
>>> On Mon, Sep 19, 2016 at 8:53 AM, Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>> On Mon, Sep 19, 2016 at 05:02:40PM +0200, Arnd Bergmann wrote:
>>>>> On Sunday, September 18, 2016 6:39:46 PM CEST Krzysztof Kozlowski wrote:
>>>>> Samsung drivers/soc update for v4.9:
>>>>> 1. Allow compile testing of exynos-mct clocksource driver on ARM64.
>>>>> 2. Document Exynos5433 PMU compatible (already used by clkout driver and more
>>>>>   will be coming soon).
>>>> 
>>>> Pulled into next/drivers, thanks
>>>> 
>>>> Just for my understanding: why do we need the exynos-mct driver on ARM64
>>>> but not the delay-timer portion of it?
>>> 
>>> I think we want all of it but Doug's optimization 3252a646aa2c
>>> ("clocksource: exynos_mct: Only use 32-bits where possible") is not
>>> ARM64 friendly. One way of dealing with it would be to prepare two
>>> versions of exynos4_read_current_timer(). One reading only lower 32-bit
>>> value for ARMv7 and second (slow) reading lower and upper for ARMv8.
>>> 
>>>> 
>>>> Is there an advantage in using MCT over the architected timer on these
>>>> chips? If so, should we also have a way to use it as the delay timer?
>>> 
>>> No, there is no real advantage... except that the SoC has some
>>> interesting "characteristics"... The timers are tightly coupled. Very
>>> tightly. I spent a lot of time and failed to boot my ARMv8 board without
>>> some MCT magic.
>> 
>> What kind of magic is that?
> 
> Most notably: the arch timer starts when MCT forward running counter
> starts. Without kicking MCT, the arch timer seems to be frozen.
> 
>> I can understand that needing the MCT for
>> some system-level timer functionality might be true (wakeups, etc),
>> but for system timesource avoiding the MMIO timer and using the arch
>> ones is a substantial performance improvement for gettimeofday() and
>> friends.
>> 
>> There was extensive discussion last year over using arch timers on
>> 5420/5422, and it fizzled out with vague comments about something not
>> working right between A15/A7 on b.L. hardware. I'm presuming whatever
>> implementation details of that SoC has since been fixed on later chips
>> (including v8). Any chance you can confirm? It'd be very nice to leave
>> MCT behind on v8 as a system time source.
> 
> Unfortunately, I cannot confirm this, at least on Exynos5433 (ARMv8). I
> played with arch and MCT timers on it and failed to get the
> arch-timer-only setup working. I did not have access to newer Exynos
> designs (Exynos 7) so I do not know how it works there.

Hi guys,

I know what Olof want to know and actually several days ago someone asked me about that. As you guys talked, a couple of years ago there were some discussions...BTW I need to contact to hardware designer before let you guys know because something needs to be confirmed by them even I know roughly.

Note I'm in vacation with my family. Will be back on this in several days with exact information.

BRs,
Kukjin

Re: [GIT PULL 1/3] ARM: soc: exynos: Drivers for v4.9

[Kukjin Kim]

2016. 10. 3. 21:19 Kukjin Kim <kgene.kim@gmail.com> wrote:

+ my samsung email

> 2016. 10. 3. 15:48 Krzysztof Kozlowski <krzk@kernel.org> wrote:
> 
>>>> On Sun, Oct 02, 2016 at 05:25:07PM -0700, Olof Johansson wrote:
>>>>> On Mon, Sep 19, 2016 at 8:53 AM, Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>>>> On Mon, Sep 19, 2016 at 05:02:40PM +0200, Arnd Bergmann wrote:
>>>>>> On Sunday, September 18, 2016 6:39:46 PM CEST Krzysztof Kozlowski wrote:
>>>>>> Samsung drivers/soc update for v4.9:
>>>>>> 1. Allow compile testing of exynos-mct clocksource driver on ARM64.
>>>>>> 2. Document Exynos5433 PMU compatible (already used by clkout driver and more
>>>>>>  will be coming soon).
>>>>> 
>>>>> Pulled into next/drivers, thanks
>>>>> 
>>>>> Just for my understanding: why do we need the exynos-mct driver on ARM64
>>>>> but not the delay-timer portion of it?
>>>> 
>>>> I think we want all of it but Doug's optimization 3252a646aa2c
>>>> ("clocksource: exynos_mct: Only use 32-bits where possible") is not
>>>> ARM64 friendly. One way of dealing with it would be to prepare two
>>>> versions of exynos4_read_current_timer(). One reading only lower 32-bit
>>>> value for ARMv7 and second (slow) reading lower and upper for ARMv8.
>>>> 
>>>>> 
>>>>> Is there an advantage in using MCT over the architected timer on these
>>>>> chips? If so, should we also have a way to use it as the delay timer?
>>>> 
>>>> No, there is no real advantage... except that the SoC has some
>>>> interesting "characteristics"... The timers are tightly coupled. Very
>>>> tightly. I spent a lot of time and failed to boot my ARMv8 board without
>>>> some MCT magic.
>>> 
>>> What kind of magic is that?
>> 
>> Most notably: the arch timer starts when MCT forward running counter
>> starts. Without kicking MCT, the arch timer seems to be frozen.
>> 
>>> I can understand that needing the MCT for
>>> some system-level timer functionality might be true (wakeups, etc),
>>> but for system timesource avoiding the MMIO timer and using the arch
>>> ones is a substantial performance improvement for gettimeofday() and
>>> friends.
>>> 
>>> There was extensive discussion last year over using arch timers on
>>> 5420/5422, and it fizzled out with vague comments about something not
>>> working right between A15/A7 on b.L. hardware. I'm presuming whatever
>>> implementation details of that SoC has since been fixed on later chips
>>> (including v8). Any chance you can confirm? It'd be very nice to leave
>>> MCT behind on v8 as a system time source.
>> 
>> Unfortunately, I cannot confirm this, at least on Exynos5433 (ARMv8). I
>> played with arch and MCT timers on it and failed to get the
>> arch-timer-only setup working. I did not have access to newer Exynos
>> designs (Exynos 7) so I do not know how it works there.
> 
> Hi guys,
> 
> I know what Olof want to know and actually several days ago someone asked me about that. As you guys talked, a couple of years ago there were some discussions...BTW I need to contact to hardware designer before let you guys know because something needs to be confirmed by them even I know roughly.
> 
> Note I'm in vacation with my family. Will be back on this in several days with exact information.
> 
> BRs,
> Kukjin

RE: [GIT PULL 1/3] ARM: soc: exynos: Drivers for v4.9

[Kukjin Kim]

Kukjin Kim wrote:

- Krzysztof's samsung email because he is not using now

> 
> 2016. 10. 3. 21:19 Kukjin Kim <kgene.kim@gmail.com> wrote:
> 
> + my samsung email
> 
> > 2016. 10. 3. 15:48 Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >
> >>>> On Sun, Oct 02, 2016 at 05:25:07PM -0700, Olof Johansson wrote:
> >>>>> On Mon, Sep 19, 2016 at 8:53 AM, Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>>>>> On Mon, Sep 19, 2016 at 05:02:40PM +0200, Arnd Bergmann wrote:
> >>>>>> On Sunday, September 18, 2016 6:39:46 PM CEST Krzysztof Kozlowski wrote:
> >>>>>> Samsung drivers/soc update for v4.9:
> >>>>>> 1. Allow compile testing of exynos-mct clocksource driver on ARM64.
> >>>>>> 2. Document Exynos5433 PMU compatible (already used by clkout
> >>>>>> driver and more  will be coming soon).
> >>>>>
> >>>>> Pulled into next/drivers, thanks
> >>>>>
> >>>>> Just for my understanding: why do we need the exynos-mct driver on
> >>>>> ARM64 but not the delay-timer portion of it?
> >>>>
> >>>> I think we want all of it but Doug's optimization 3252a646aa2c
> >>>> ("clocksource: exynos_mct: Only use 32-bits where possible") is not
> >>>> ARM64 friendly. One way of dealing with it would be to prepare two
> >>>> versions of exynos4_read_current_timer(). One reading only lower
> >>>> 32-bit value for ARMv7 and second (slow) reading lower and upper for ARMv8.
> >>>>
> >>>>>
> >>>>> Is there an advantage in using MCT over the architected timer on
> >>>>> these chips? If so, should we also have a way to use it as the delay timer?
> >>>>
> >>>> No, there is no real advantage... except that the SoC has some
> >>>> interesting "characteristics"... The timers are tightly coupled.
> >>>> Very tightly. I spent a lot of time and failed to boot my ARMv8
> >>>> board without some MCT magic.
> >>>
> >>> What kind of magic is that?
> >>
> >> Most notably: the arch timer starts when MCT forward running counter
> >> starts. Without kicking MCT, the arch timer seems to be frozen.
> >>
> >>> I can understand that needing the MCT for some system-level timer
> >>> functionality might be true (wakeups, etc),

Yes correct, the MCT is designed for the power consumption related
functionalities such as cluster power down

> >>> but for system
> >>> timesource avoiding the MMIO timer and using the arch ones is a
> >>> substantial performance improvement for gettimeofday() and friends.
> >>>

At this moment, we can use the ARM arch timers as clocksource so I think
no performance degradation (some latency?) with using the CP15 access for
the gettimeofday() and friends

> >>> There was extensive discussion last year over using arch timers on
> >>> 5420/5422, and it fizzled out with vague comments about something
> >>> not working right between A15/A7 on b.L. hardware.

Current Exynos SoCs including ARMv8 architecture based have no hardware
something which means 'not working right'

> >>> I'm presuming
> >>> whatever implementation details of that SoC has since been fixed on
> >>> later chips (including v8). Any chance you can confirm? It'd be very
> >>> nice to leave MCT behind on v8 as a system time source.

It is depending on system level design architecture. If we don't need to
support some power mode such as cluster power down, we can use arch timers
without the MCT but actual product needed to support it for power consumption.

Let me add some comments.
According to the ARM architecture design, the ARM arch timers require toggle
from outside of the core as timer source and we're using the MCT for it. And
we can use the ARM arch timers as clocksource not the MCT on current Exynos.

> >> Unfortunately, I cannot confirm this, at least on Exynos5433 (ARMv8).
> >> I played with arch and MCT timers on it and failed to get the
> >> arch-timer-only setup working. I did not have access to newer Exynos
> >> designs (Exynos 7) so I do not know how it works there.
> >
> > Hi guys,
> >
> > I know what Olof want to know and actually several days ago someone asked me about that. As you guys
> talked, a couple of years ago there were some discussions...BTW I need to contact to hardware designer
> before let you guys know because something needs to be confirmed by them even I know roughly.
> >
> > Note I'm in vacation with my family. Will be back on this in several days with exact information.
> >
> > BRs,
> > Kukjin

k-gene