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From: Sven Van Asbroeck <thesven73@gmail.com>
To: Clemens Gruber <clemens.gruber@pqgruber.com>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	linux-pwm@vger.kernel.org
Subject: Re: [PATCH v5 2/7] pwm: pca9685: Support hardware readout
Date: Fri, 29 Jan 2021 16:24:06 -0500	[thread overview]
Message-ID: <CAGngYiXxfz7rtsw4zSj5QX7Lj7hvnoESqyUE_2__=oDaRmGGJQ@mail.gmail.com> (raw)
In-Reply-To: <YBRyG0vv3gRzygSB@workstation.tuxnet>

Hi Clemens,

On Fri, Jan 29, 2021 at 3:37 PM Clemens Gruber
<clemens.gruber@pqgruber.com> wrote:
>
> Is the driver really responsible for bootloaders that program the chip
> with invalid values?

No, but it's responsible for correcting invalid values. Otherwise the driver
doesn't work.

> The chip comes out of PoR with sane default values. If the bootloader of
> a user messes them up, isn't that a bootloader problem instead of a
> Linux kernel driver problem?

Invalid values are only half the problem. The other half is that two valid
values might produce the same output, e.g.:

LEN_ON = 409, LED_OFF = 1228 and
LED_ON = 419, LED_OFF = 1238
produce the same result. you can't see the difference between the two
when scoping the channel. there are probably more ways to do this,
some might surprise us. It's a tricky chip.

  reply	other threads:[~2021-01-29 21:25 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20201216125320.5277-1-clemens.gruber@pqgruber.com>
     [not found] ` <20201216125320.5277-2-clemens.gruber@pqgruber.com>
2020-12-17  4:00   ` [PATCH v5 2/7] pwm: pca9685: Support hardware readout Sven Van Asbroeck
2020-12-17 17:43     ` Clemens Gruber
2020-12-17 17:52       ` Sven Van Asbroeck
2021-01-03 17:04         ` Clemens Gruber
2021-01-07 14:18           ` Sven Van Asbroeck
2021-01-11 20:43           ` Uwe Kleine-König
2021-03-22  8:34             ` Thierry Reding
2021-03-31 10:25               ` Uwe Kleine-König
2021-03-31 15:52                 ` Thierry Reding
2021-04-06  6:33                   ` Uwe Kleine-König
2021-04-06 13:47                     ` Thierry Reding
2021-04-06 20:44                       ` Uwe Kleine-König
2021-03-22  8:15           ` Thierry Reding
2021-01-11 20:35       ` Uwe Kleine-König
2021-01-14 17:16         ` Clemens Gruber
2021-01-14 18:05           ` Uwe Kleine-König
2021-03-22  8:53           ` Thierry Reding
2021-01-29 13:42         ` Sven Van Asbroeck
2021-01-29 16:31           ` Clemens Gruber
2021-01-29 18:05             ` Sven Van Asbroeck
2021-01-29 20:37               ` Clemens Gruber
2021-01-29 21:24                 ` Sven Van Asbroeck [this message]
2021-01-29 22:16                   ` Sven Van Asbroeck
2021-02-01 17:24                     ` Clemens Gruber
2021-03-01 21:52                       ` Uwe Kleine-König
2021-03-04 13:22                         ` Clemens Gruber
2021-02-14 14:46                 ` Clemens Gruber
2021-03-22  9:19                 ` Thierry Reding
2021-03-22  9:38                   ` Andy Shevchenko
2021-03-22 11:22                     ` Uwe Kleine-König
2021-03-22 11:40                       ` Andy Shevchenko
2021-03-22 11:48                         ` Uwe Kleine-König
2021-03-22 12:15                           ` Andy Shevchenko
2021-03-22 13:25                             ` Uwe Kleine-König
2021-03-27 16:05                   ` Clemens Gruber
2021-03-22  9:14               ` Thierry Reding
2021-03-22  8:47         ` Thierry Reding
2020-12-15 21:22 [PATCH v5 1/7] pwm: pca9685: Switch to atomic API Clemens Gruber
2020-12-15 21:22 ` [PATCH v5 2/7] pwm: pca9685: Support hardware readout Clemens Gruber

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