From: Jeff LaBundy <jeff@labundy.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"lars@metafoo.de" <lars@metafoo.de>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
"linux-pwm@vger.kernel.org" <linux-pwm@vger.kernel.org>,
"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
"dmitry.torokhov@gmail.com" <dmitry.torokhov@gmail.com>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
"thierry.reding@gmail.com" <thierry.reding@gmail.com>,
"pmeerw@pmeerw.net" <pmeerw@pmeerw.net>,
"linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
"lee.jones@linaro.org" <lee.jones@linaro.org>,
"jic23@kernel.org" <jic23@kernel.org>,
"knaack.h@gmx.de" <knaack.h@gmx.de>
Subject: Re: [PATCH v2 4/7] pwm: Add support for Azoteq IQS620A PWM generator
Date: Wed, 1 Jan 2020 22:39:36 +0000 [thread overview]
Message-ID: <20200101223933.GB14339@labundy.com> (raw)
In-Reply-To: <20191222214851.kapsro6b6qylke43@pengutronix.de>
Hi Uwe,
On Sun, Dec 22, 2019 at 10:48:51PM +0100, Uwe Kleine-König wrote:
> Hello Jeff,
>
> On Sat, Dec 21, 2019 at 03:28:01AM +0000, Jeff LaBundy wrote:
> > I heard back from the vendor today; they've acknowledged the limitation and
> > are considering adding support for 0% in a future ROM spin. In the meantime,
> > they've agreed to describe the high-impedance behavior in the data sheet as
> > well as include the pull-down resistor in an example schematic.
>
> Oh wow, seems like a good vendor then. :-)
>
> > > > Option (3) seems like overkill for such a simple PWM, and ultimately doesn't
> > > > add any value because I don't want to allow option (1) behavior in any case.
> > > > Whether the PWM is disabled because it is truly disabled or to simulate a 0%
> > > > duty cycle as in option (2), the pull-down is ultimately required regardless
> > > > of whether or not the data sheet happens to go into such detail.
> > >
> > > Actually I like option 3 best.
> > >
> >
> > Based on your other feedback, I'm moving forward under the impression that
> > you'll still accept option (2); please let me know if I have misunderstood
> > (thank you for being flexible).
>
> Yeah, that's fine. If in the end it shows that this is a bad idea we can
> still change to (3).
>
Sounds great. As soon as 5.5-rc5 lands this weekend, I'll rebase v3 and
send it out.
I failed to catch this in my previous reply, but the comment I've added
to iqs620_pwm_get_state actually reads as follows:
/*
* Since the device cannot generate a 0% duty cycle, requests to do so
* force subsequent calls to iqs620_pwm_get_state to report the output
* as disabled with duty cycle equal to that which was in use prior to
* the request. This is not ideal, but is the best compromise based on
* the capabilities of the device.
*/
This matches the present implementation, not your proposed comment that
claims duty cycle is clamped to 1 / 256 ms following a request for a 0%
duty cycle.
This seems OK since the concept of a duty cycle or period aren't really
relevant if the output is disabled in my opinion. However if you prefer
I update iqs620_pwm_apply to clamp duty cycle to 1 / 256 ms (instead of
leaving it untouched) in this case, please let me know.
> Best regards
> Uwe
>
> --
> Pengutronix e.K. | Uwe Kleine-König |
> Industrial Linux Solutions | https://www.pengutronix.de/ |
Wishing you a Happy New Year,
Jeff LaBundy
next prev parent reply other threads:[~2020-01-01 22:39 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 0:38 [PATCH v2 0/7] Add support for Azoteq IQS620A/621/622/624/625 Jeff LaBundy
2019-12-09 0:38 ` [PATCH v2 1/7] dt-bindings: Add bindings " Jeff LaBundy
2019-12-18 23:52 ` Rob Herring
2019-12-20 4:00 ` Jeff LaBundy
2019-12-24 21:55 ` Rob Herring
2020-01-01 21:32 ` Jeff LaBundy
2019-12-09 0:38 ` [PATCH v2 2/7] mfd: Add support " Jeff LaBundy
2019-12-09 0:38 ` [PATCH v2 3/7] input: keyboard: " Jeff LaBundy
2019-12-09 0:38 ` [PATCH v2 4/7] pwm: Add support for Azoteq IQS620A PWM generator Jeff LaBundy
2019-12-09 7:32 ` Uwe Kleine-König
2019-12-10 0:03 ` Jeff LaBundy
2019-12-10 7:22 ` Uwe Kleine-König
2019-12-15 20:36 ` Jeff LaBundy
2019-12-16 9:19 ` Uwe Kleine-König
2019-12-20 3:19 ` Jeff LaBundy
2019-12-20 8:59 ` Uwe Kleine-König
2019-12-21 3:28 ` Jeff LaBundy
2019-12-22 21:48 ` Uwe Kleine-König
2020-01-01 22:39 ` Jeff LaBundy [this message]
2020-01-07 11:19 ` Uwe Kleine-König
2020-01-10 4:29 ` Jeff LaBundy
2020-01-10 7:25 ` Uwe Kleine-König
2019-12-09 0:38 ` [PATCH v2 5/7] iio: temperature: Add support for Azoteq IQS620AT temperature sensor Jeff LaBundy
2019-12-15 16:34 ` Jonathan Cameron
2019-12-09 0:38 ` [PATCH v2 6/7] iio: light: Add support for Azoteq IQS621/622 ambient light sensors Jeff LaBundy
2019-12-15 16:47 ` Jonathan Cameron
2019-12-09 0:38 ` [PATCH v2 7/7] iio: position: Add support for Azoteq IQS624/625 angle sensors Jeff LaBundy
2019-12-15 16:53 ` Jonathan Cameron
2020-01-01 22:51 ` Jeff LaBundy
2020-01-02 7:57 ` Lee Jones
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