From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: "Tanwar, Rahul" <rahul.tanwar@linux.intel.com>
Cc: linux-pwm@vger.kernel.org, thierry.reding@gmail.com,
p.zabel@pengutronix.de, robh+dt@kernel.org,
linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
andriy.shevchenko@intel.com, songjun.Wu@intel.com,
cheol.yong.kim@intel.com, qi-ming.wu@intel.com,
rahul.tanwar.linux@gmail.com
Subject: Re: [PATCH v5 2/2] Add PWM fan controller driver for LGM SoC
Date: Mon, 27 Jul 2020 22:00:44 +0200 [thread overview]
Message-ID: <20200727200044.qmrpjua3fewli3vo@pengutronix.de> (raw)
In-Reply-To: <70fde2ba-b38f-a0d6-bc2d-89c074afd466@linux.intel.com>
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Hello,
On Mon, Jul 27, 2020 at 03:30:16PM +0800, Tanwar, Rahul wrote:
> On 27/7/2020 3:01 pm, Uwe Kleine-König wrote:
> > In v4 you had:
> >
> > if (state->polarity != PWM_POLARITY_NORMAL ||
> > state->period < pc->period)
> > return -EINVAL;
> >
> > That's the right thing to do (even though I was unsettled at one point
> > and wrote it was wrong). The check in v5 with state->period !=
> > pc->period is wrong.
>
> Does that mean we should allow state->period >= pc->period cases?
Yes, the driver is supposed to implement the longest period not longer
than the requested one. This implies everything >= pc->period is fine.
> If the state->period is greater than HW supported pc->period and
> if we allow it then the duty cycle will again be evaluated to be
> incorrect/higher than requested duty cycle. Am i missing something
> else? Thanks.
Yes, similar as with period you're supposed to implement the longest
duty cycle your hardware supports and that is not longer than the
requested duty cycle.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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prev parent reply other threads:[~2020-07-27 20:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-23 7:44 [PATCH v5 0/2] pwm: intel: Add PWM driver for a new SoC Rahul Tanwar
2020-07-23 7:44 ` [PATCH v5 1/2] Add DT bindings YAML schema for PWM fan controller of LGM SoC Rahul Tanwar
2020-07-23 15:42 ` Rob Herring
2020-07-23 7:44 ` [PATCH v5 2/2] Add PWM fan controller driver for " Rahul Tanwar
2020-07-23 16:15 ` Uwe Kleine-König
2020-07-27 6:04 ` Tanwar, Rahul
2020-07-27 7:01 ` Uwe Kleine-König
2020-07-27 7:30 ` Tanwar, Rahul
2020-07-27 20:00 ` Uwe Kleine-König [this message]
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