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

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Date:   Thu, 1 Sep 2016 20:24:19 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     lgirdwood@...il.com, mka@...omium.org, briannorris@...omium.org,
        javier@...hile0.org, linux-rockchip@...ts.infradead.org,
        robh+dt@...nel.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:

> 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.

Why is this specific to regulators implemented with PWM controllers?
Most DCDCs have a PWM element and the concept of a hard time limit for
transition rather than a ramp rate doesn't seem like it'd be unique.

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