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From: Rob Herring <robh@kernel.org>
To: Matthias Kaehlcke <mka@chromium.org>
Cc: Mark Brown <broonie@kernel.org>,
	lgirdwood@gmail.com, Douglas Anderson <dianders@chromium.org>,
	briannorris@chromium.org, javier@dowhile0.org,
	mark.rutland@arm.com, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org
Subject: Re: [PATCH v5 6/6] regulator: core: Prevent falling too fast
Date: Fri, 23 Sep 2016 10:16:25 -0500	[thread overview]
Message-ID: <20160923151625.GA14369@rob-hp-laptop> (raw)
In-Reply-To: <1473871930-99603-6-git-send-email-mka@chromium.org>

On Wed, Sep 14, 2016 at 09:52:10AM -0700, Matthias Kaehlcke wrote:
> From: Douglas Anderson <dianders@chromium.org>
> 
> On some boards it is possible that transitioning the regulator downwards
> too fast will trigger the over voltage protection (OVP) on the
> regulator. This is because until the voltage actually falls there is
> time when the requested voltage is much lower than the actual voltage.
> 
> We'll fix this OVP problem by allowing users to specify the maximum
> voltage that we can safely fall. The maximum safe voltage decrease
> is specified as a percentage of the current voltage. The driver will
> then break things into separate steps with a delay in between.
> 
> In order to figure out what the delay should be we need to figure out
> how slowly the voltage rail might fall in the worst (slowest) case.
> We'll assume this worst case is present and delay so we know for sure
> that we've finished each step.
> 
> In this patch we actually block returning from the set_voltage() call
> until we've finished delaying. A future patch atop this one might
> choose to return more immediately and let the voltages fall in the
> background. That would possibly allow us to cancel a slow downward
> decay if there was a request to go back up.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> Changes in v5:
> - Leave set_voltage tracepoints where they were
> - Fixed error handling in code dealing with the device tree, return an error if configuration is invalid
> - Fixed coding style and formatting issues
> - Updated commit message
> 
>  .../devicetree/bindings/regulator/regulator.txt    |  7 ++++

For the binding:

Acked-by: Rob Herring <robh@kernel.org>

>  drivers/regulator/core.c                           | 49 +++++++++++++++++++---
>  drivers/regulator/of_regulator.c                   | 42 ++++++++++++++++++-
>  include/linux/regulator/machine.h                  |  2 +
>  4 files changed, 93 insertions(+), 7 deletions(-)

  parent reply	other threads:[~2016-09-23 15:16 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-14 16:52 [PATCH v5 1/6] regulator: core: Use local ops variable in _regulator_do_set_voltage() Matthias Kaehlcke
2016-09-14 16:52 ` [PATCH v5 2/6] regulator: core: Simplify error flow " Matthias Kaehlcke
2016-09-16 17:40   ` Applied "regulator: core: Simplify error flow in _regulator_do_set_voltage()" to the regulator tree Mark Brown
2016-09-16 17:40     ` Mark Brown
2016-09-14 16:52 ` [PATCH v5 3/6] regulator: core: Don't skip set_voltage_time when ramp delay disabled Matthias Kaehlcke
2016-09-16 17:40   ` Applied "regulator: core: Don't skip set_voltage_time when ramp delay disabled" to the regulator tree Mark Brown
2016-09-16 17:40     ` Mark Brown
2016-09-14 16:52 ` [PATCH v5 4/6] regulator: core: Add set_voltage_time op Matthias Kaehlcke
2016-09-16 17:40   ` Applied "regulator: core: Add set_voltage_time op" to the regulator tree Mark Brown
2016-09-16 17:40     ` Mark Brown
2016-09-14 16:52 ` [PATCH v5 5/6] regulator: core: Add support for a fixed delay after voltage changes Matthias Kaehlcke
2016-09-14 16:52   ` Matthias Kaehlcke
2016-09-23 15:14   ` Rob Herring
2016-09-14 16:52 ` [PATCH v5 6/6] regulator: core: Prevent falling too fast Matthias Kaehlcke
2016-09-14 16:52   ` Matthias Kaehlcke
2016-09-14 21:35   ` kbuild test robot
2016-09-14 21:35     ` kbuild test robot
2016-09-23 15:16   ` Rob Herring [this message]
2016-09-14 17:16 ` Applied "regulator: core: Use local ops variable in _regulator_do_set_voltage()" to the regulator tree Mark Brown
2016-09-14 17:16   ` Mark Brown

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