From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: "Mårten Lindahl" <marten.lindahl@axis.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
Thierry Reding <thierry.reding@gmail.com>,
Lee Jones <lee.jones@linaro.org>,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-pwm@vger.kernel.org,
kernel@axis.com
Subject: Re: [PATCH v3] pwm: pwm-samsung: Trigger manual update when disabling PWM
Date: Fri, 29 Oct 2021 18:06:44 +0200 [thread overview]
Message-ID: <20211029160644.vtaaxy2txszcjybn@pengutronix.de> (raw)
In-Reply-To: <20210909101042.17431-1-marten.lindahl@axis.com>
[-- Attachment #1: Type: text/plain, Size: 1406 bytes --]
On Thu, Sep 09, 2021 at 12:10:42PM +0200, Mårten Lindahl wrote:
> When duty-cycle is at full level (100%), the TCNTn and TCMPn registers
> needs to be flushed in order to disable the signal. The PWM manual does
> not say anything about this, but states that only clearing the TCON
> auto-reload bit should be needed, and this seems to be true when the PWM
> duty-cycle is not at full level. This can be observed on an Axis
> ARTPEC-8, by running:
>
> echo <period> > pwm/period
> echo <period> > pwm/duty_cycle
> echo 1 > pwm/enable
> echo 0 > pwm/enable
>
> Since the TCNTn and TCMPn registers are activated when enabling the PWM
> (setting TCON auto-reload bit), and are not touched when disabling the
> PWM, the double buffered auto-reload function seems to be still active.
> Lowering duty-cycle, and restoring it again in between the enabling and
> disabling, makes the disable work since it triggers a reload of the
> TCNTn and TCMPn registers.
>
> Fix this by securing a reload of the TCNTn and TCMPn registers when
> disabling the PWM and having a full duty-cycle.
>
> Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Thanks
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
prev parent reply other threads:[~2021-10-29 16:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-09 10:10 [PATCH v3] pwm: pwm-samsung: Trigger manual update when disabling PWM Mårten Lindahl
2021-09-09 10:40 ` Krzysztof Kozlowski
2021-10-29 16:06 ` Uwe Kleine-König [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211029160644.vtaaxy2txszcjybn@pengutronix.de \
--to=u.kleine-koenig@pengutronix.de \
--cc=kernel@axis.com \
--cc=krzysztof.kozlowski@canonical.com \
--cc=lee.jones@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-pwm@vger.kernel.org \
--cc=linux-samsung-soc@vger.kernel.org \
--cc=marten.lindahl@axis.com \
--cc=thierry.reding@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).