From: Laxman Dewangan <ldewangan@nvidia.com>
To: Douglas Anderson <dianders@chromium.org>,
Mark Brown <broonie@kernel.org>
Cc: <boris.brezillon@free-electrons.com>, <lee.jones@linaro.org>,
<briannorris@chromium.org>, <linux-rockchip@lists.infradead.org>,
"Heiko Stuebner" <heiko@sntech.de>, <thierry.reding@gmail.com>,
<lgirdwood@gmail.com>, <linux-kernel@vger.kernel.org>,
<afrid@nvidia.com>
Subject: Re: [PATCH v2] regulator: pwm: Fix regulator ramp delay for continuous mode
Date: Thu, 7 Jul 2016 14:06:23 +0530 [thread overview]
Message-ID: <577E1487.9010000@nvidia.com> (raw)
In-Reply-To: <1467830521-15300-1-git-send-email-dianders@chromium.org>
On Thursday 07 July 2016 12:12 AM, Douglas Anderson wrote:
> The original commit adding support for continuous voltage mode didn't
> handle the regulator ramp delay properly. It treated the delay as a
> fixed delay in uS despite the property being defined as uV / uS. Let's
> adjust it. Luckily there appear to be no users of this ramp delay for
> PWM regulators (as per grepping through device trees in linuxnext).
>
> Note also that the upper bound of usleep_range probably shouldn't be a
> full 1 ms longer than the lower bound since I've seen plenty of hardware
> with a ramp rate of ~5000 uS / uV and for small jumps the total delays
> are in the tens of uS. 1000 is way too much. We'll try to be dynamic
> and use 10%.
>
> NOTE: This commit doesn't add support for regulator-enable-ramp-delay.
> That could be done in a future patch when someone has a user of that
> featre.
>
> Though this patch is shows as "fixing" a bug, there are no actual known
> users of continuous mode PWM regulator w/ ramp delay in mainline and so
> this likely won't have any effect on anyone unless they are working
> out-of-tree with private patches. For anyone in this state, it is
> highly encouraged to also pick Boris Brezillon's WIP patches to get
> yourself a reliable and glitch-free regulator.
>
> Fixes: 4773be185a0f ("regulator: pwm-regulator: Add support for continuous-voltage")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
Looks fine here.
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
BTW, for some PWM regulator, the settling time for voltage change is
same for any steps.
next prev parent reply other threads:[~2016-07-07 8:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-06 18:42 [PATCH v2] regulator: pwm: Fix regulator ramp delay for continuous mode Douglas Anderson
2016-07-07 8:36 ` Laxman Dewangan [this message]
2016-07-07 16:30 ` Doug Anderson
2016-07-07 18:23 ` Aleksandr Frid
2016-07-07 18:31 ` Doug Anderson
2016-07-07 18:43 ` Aleksandr Frid
2016-07-08 8:53 ` Mark Brown
2016-07-07 10:01 ` Applied "regulator: pwm: Fix regulator ramp delay for continuous mode" to the regulator tree Mark Brown
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