linux-kernel - Re: [PATCH v13] pwm: opencores: Add PWM driver support

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Message-ID: <jptwjtzpoxzvzkcdicjrye46iy5uretz5oqxh6gu2zinv7ikae@3vpemq2ewywj>
Date: Wed, 7 Aug 2024 07:57:05 +0200
From: Uwe Kleine-König <u.kleine-koenig@...libre.com>
To: William Qiu <william.qiu@...rfivetech.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>, Hal Feng <hal.feng@...rfivetech.com>, 
	Philipp Zabel <p.zabel@...gutronix.de>
Subject: Re: [PATCH v13] pwm: opencores: Add PWM driver support

Hello William,

On Wed, Aug 07, 2024 at 03:41:15AM +0000, William Qiu wrote:
> > -----Original Message-----
> > From: Uwe Kleine-König <u.kleine-koenig@...libre.com>
> > [...]
> > On Tue, Jul 02, 2024 at 04:38:48PM +0800, William Qiu wrote:
> > > + * - The hardware will have a conversion cycle when reconfiguring.
> > 
> > I don't understand that.
> > .
> For example, after the PWM duty cycle is changed from 50% to 80%,
> it is not a direct change, but there is a conversion period. The waveform
> during the conversion period will vary depending on whether it is high or
> low when reconfigured.

Is it "just" that the new settings become active immediately and so if
you change the relative duty_cycle from 50% to 80% and the current
period is "done" between 50% and 80% you get three instead of one level
change during that period?

If it's that, I'd describe that as: When configuration changes are done,
they get active immediately without resetting the counter. This might
result in one period affected by both old and new settings.

Best regards
Uwe

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