linux-kernel - Re: [PATCH v3 1/2] regulator: pwm: Add support for a fixed delay after duty cycle changes

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Date:   Fri, 2 Sep 2016 10:11:51 -0500
From:   Rob Herring <robh@...nel.org>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     Mark Brown <broonie@...nel.org>, lgirdwood@...il.com,
        mka@...omium.org, briannorris@...omium.org, javier@...hile0.org,
        linux-rockchip@...ts.infradead.org, mark.rutland@....com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v3 1/2] regulator: pwm: Add support for a fixed delay
 after duty cycle changes

On Tue, Aug 30, 2016 at 09:21:15PM -0700, Douglas Anderson wrote:
> From: Matthias Kaehlcke <mka@...omium.org>
> 
> A change of the duty cycle doesn't necessarily cause an immediate switch
> to the target voltage.  On many PWM regulators there is a fixed "settle
> time" (irrespective of the jump size) that we need to wait after an
> upward jump.  This change introduces the device tree property
> "settle-time-up-us" which allows us to specify a fixed delay after a
> voltage increase.
> 
> We don't add an option of a fixed delay on the way down for now because
> the way down is probably modelled best with a ramp rate, not a fixed
> delay.
> 
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
> Changes in v3:
> - Took out fixed delay for falling transitions
> - Updated description
> 
>  .../devicetree/bindings/regulator/pwm-regulator.txt   |  6 ++++++

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

>  drivers/regulator/pwm-regulator.c                     | 19 +++++++++++++++----
>  2 files changed, 21 insertions(+), 4 deletions(-)