From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Emil Lenngren <emil.lenngren@gmail.com>
Cc: Roman Beranek <roman.beranek@prusa3d.cz>,
Thierry Reding <thierry.reding@gmail.com>,
Lee Jones <lee.jones@linaro.org>,
Maxime Ripard <mripard@kernel.org>, Chen-Yu Tsai <wens@csie.org>,
Jernej Skrabec <jernej.skrabec@siol.net>,
linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-sunxi@lists.linux.dev, linux-sunxi@googlegroups.com,
Roman Beranek <roman.beranek@prusa3d.com>
Subject: Re: [PATCH] pwm: sun4i: Avoid waiting until the next period
Date: Wed, 12 May 2021 06:41:33 +0200 [thread overview]
Message-ID: <20210512044133.6yfwyluzdx6yfh4c@pengutronix.de> (raw)
In-Reply-To: <CAO1O6seU7t==O=yCVBQK0iAkeEyO3dbRQ71obJh3Jm26xxWobw@mail.gmail.com>
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Hello Emil,
On Wed, May 12, 2021 at 02:55:26AM +0200, Emil Lenngren wrote:
> Well that's one way of "solving it" ;)
>
> But on what hardware do you really need to wait until one full pulse
> cycle ends, before a disable command takes effect?
>
> On the hardware I've tested on (GR8 and V3s), it's enough to wait at
> most two clock cycles in order for it to take effect before we can
> close the gate. And with clock cycle I mean 24 MHz divided by the
> prescaler. With prescaler 1, that's 84 nanoseconds. By closing the
> gate when the pwm should be disabled, I guess we could save some
> nanoampere or microampere (is this important?)
If I understood correctly you really have to wait longer to achieve that
the output is inactive in the disabled state. Do you talk about the same
thing?
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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next prev parent reply other threads:[~2021-05-12 4:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 22:00 [PATCH] pwm: sun4i: Avoid waiting until the next period Roman Beranek
2021-05-12 0:55 ` Emil Lenngren
2021-05-12 4:13 ` Roman Beranek
2021-05-12 4:41 ` Uwe Kleine-König [this message]
2021-05-12 9:18 ` Emil Lenngren
2021-05-25 16:41 ` Thierry Reding
2021-05-27 12:10 ` Roman Beranek
2021-05-27 13:53 ` Alexandre Belloni
2021-06-25 17:25 ` Uwe Kleine-König
2021-05-12 5:31 ` Roman Beranek
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