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Re: [PATCH V3 0/9] PM / OPP: Multiple regulator support

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  Re: [PATCH V3 0/9] PM / OPP: Multiple regulator support Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-02 06:00 +0100
    Re: [PATCH V3 0/9] PM / OPP: Multiple regulator support Stephen Boyd <sboyd@codeaurora.org> - 2016-11-10 02:20 +0100
      Re: [PATCH V3 0/9] PM / OPP: Multiple regulator support Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-10 05:20 +0100

#1513644 — Re: [PATCH V3 0/9] PM / OPP: Multiple regulator support

On 26-10-16, 12:02, Viresh Kumar wrote:
> Hi,
> 
> Some platforms (like TI) have complex DVFS configuration for CPU
> devices, where multiple regulators are required to be configured to
> change DVFS state of the device. This was explained well by Nishanth
> earlier [1].
> 
> One of the major complaints around multiple regulators case was that the
> DT isn't responsible in any way to represent the ordering in which
> multiple supplies need to be programmed, before or after frequency
> change. It was considered in this patch and such information is left to
> the platform specific OPP driver now, which can register its own
> opp_set_rate() callback with the OPP core and the OPP core will then
> call it during DVFS.
> 
> The patches are tested on Exynos5250 (Dual A15). I have hacked around DT
> and code to pass values for multiple regulators and verified that they
> are all properly read by the kernel (using debugfs interface).
> 
> Dave Gerlach has already tested it on the real TI platforms and it works
> well for him.
> 
> This is rebased over: linux-next branch in the PM tree.
> 
> V2->V3:
> - The last patch is new
> - Removed a debug leftover pr_info() message
> - Renamed few names as s/set_rate/set_opp
> - Removed a TODO comment (as it is done now with this series)
> - created struct for min_uV and max_uV
> - kerneldoc comments for structures in pm_opp.h
> - s/const char */const char * const
> - use kasprintf()
> - Some more minor reformatting
> - More Ack/RBY tags added

@Stephen: Can you please provide further comments or Acks ?

-- 
viresh

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#1518615

On 11/02, Viresh Kumar wrote:
> On 26-10-16, 12:02, Viresh Kumar wrote:
> > Hi,
> > 
> > Some platforms (like TI) have complex DVFS configuration for CPU
> > devices, where multiple regulators are required to be configured to
> > change DVFS state of the device. This was explained well by Nishanth
> > earlier [1].
> > 
> > One of the major complaints around multiple regulators case was that the
> > DT isn't responsible in any way to represent the ordering in which
> > multiple supplies need to be programmed, before or after frequency
> > change. It was considered in this patch and such information is left to
> > the platform specific OPP driver now, which can register its own
> > opp_set_rate() callback with the OPP core and the OPP core will then
> > call it during DVFS.
> > 
> > The patches are tested on Exynos5250 (Dual A15). I have hacked around DT
> > and code to pass values for multiple regulators and verified that they
> > are all properly read by the kernel (using debugfs interface).
> > 
> > Dave Gerlach has already tested it on the real TI platforms and it works
> > well for him.
> > 
> > This is rebased over: linux-next branch in the PM tree.
> > 
> > V2->V3:
> > - The last patch is new
> > - Removed a debug leftover pr_info() message
> > - Renamed few names as s/set_rate/set_opp
> > - Removed a TODO comment (as it is done now with this series)
> > - created struct for min_uV and max_uV
> > - kerneldoc comments for structures in pm_opp.h
> > - s/const char */const char * const
> > - use kasprintf()
> > - Some more minor reformatting
> > - More Ack/RBY tags added
> 
> @Stephen: Can you please provide further comments or Acks ?
> 

Where did we end up on the topic of RCU usage in OPP? I'd rather
we figure that out before investing more time in reviewing code
that we may end up completely rewriting in the future.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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#1518684

On 09-11-16, 17:19, Stephen Boyd wrote:
> On 11/02, Viresh Kumar wrote:
> > On 26-10-16, 12:02, Viresh Kumar wrote:
> > > Hi,
> > > 
> > > Some platforms (like TI) have complex DVFS configuration for CPU
> > > devices, where multiple regulators are required to be configured to
> > > change DVFS state of the device. This was explained well by Nishanth
> > > earlier [1].
> > > 
> > > One of the major complaints around multiple regulators case was that the
> > > DT isn't responsible in any way to represent the ordering in which
> > > multiple supplies need to be programmed, before or after frequency
> > > change. It was considered in this patch and such information is left to
> > > the platform specific OPP driver now, which can register its own
> > > opp_set_rate() callback with the OPP core and the OPP core will then
> > > call it during DVFS.
> > > 
> > > The patches are tested on Exynos5250 (Dual A15). I have hacked around DT
> > > and code to pass values for multiple regulators and verified that they
> > > are all properly read by the kernel (using debugfs interface).
> > > 
> > > Dave Gerlach has already tested it on the real TI platforms and it works
> > > well for him.
> > > 
> > > This is rebased over: linux-next branch in the PM tree.
> > > 
> > > V2->V3:
> > > - The last patch is new
> > > - Removed a debug leftover pr_info() message
> > > - Renamed few names as s/set_rate/set_opp
> > > - Removed a TODO comment (as it is done now with this series)
> > > - created struct for min_uV and max_uV
> > > - kerneldoc comments for structures in pm_opp.h
> > > - s/const char */const char * const
> > > - use kasprintf()
> > > - Some more minor reformatting
> > > - More Ack/RBY tags added
> > 
> > @Stephen: Can you please provide further comments or Acks ?
> > 
> 
> Where did we end up on the topic of RCU usage in OPP? I'd rather
> we figure that out before investing more time in reviewing code
> that we may end up completely rewriting in the future.

We haven't decided anything on that yet and I don't think there is any reason to
block this series for that. There is lots of existing code that needs to be
updated if we decide to walk that path and I wouldn't mind a small addition to
that from this series.

Lots of effort Coding/testing/reviewing has already gone into this work and we
better get it merged now.

-- 
viresh

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