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From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Paul Cercueil <paul@crapouillou.net>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ralf Baechle <ralf@linux-mips.org>,
	Paul Burton <paul.burton@mips.com>,
	James Hogan <jhogan@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
	linux-pwm@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org,
	linux-mips@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-clk@vger.kernel.org
Subject: Re: [PATCH v9 12/27] pwm: jz4740: Use regmap from TCU driver
Date: Sat, 5 Jan 2019 22:18:20 +0100	[thread overview]
Message-ID: <20190105211820.lax3opgdhyn662tw@pengutronix.de> (raw)
In-Reply-To: <1546721178.28727.0@crapouillou.net>

Hello Paul,

On Sat, Jan 05, 2019 at 05:46:18PM -0300, Paul Cercueil wrote:
> On Sat, Jan 5, 2019 at 4:42 PM, Uwe Kleine-König
> <u.kleine-koenig@pengutronix.de> wrote:
> > On Thu, Dec 27, 2018 at 07:13:04PM +0100, Paul Cercueil wrote:
> > >  The ingenic-timer "TCU" driver provides us with a regmap, that we
> > > can
> > >  use to safely access the TCU registers.
> > > 
> > >  While this driver is devicetree-compatible, it is never (as of now)
> > >  probed from devicetree, so this change does not introduce a ABI
> > > problem
> > >  with current devicetree files.
> > 
> > Does it change behaviour? If so, how?
> 
> No, it does not change the behaviour.

Then this paragraph in the commit log can better be dropped.

> > >  @@ -113,26 +117,37 @@ static int jz4740_pwm_apply(struct pwm_chip
> > > *chip, struct pwm_device *pwm,
> > > 
> > >   	jz4740_pwm_disable(chip, pwm);
> > > 
> > >  -	jz4740_timer_set_count(pwm->hwpwm, 0);
> > >  -	jz4740_timer_set_duty(pwm->hwpwm, duty);
> > >  -	jz4740_timer_set_period(pwm->hwpwm, period);
> > >  +	/* Set abrupt shutdown */
> > >  +	regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
> > >  +			   TCU_TCSR_PWM_SD, TCU_TCSR_PWM_SD);
> > 
> > I think I already pointed that out before: abrupt mode is wrong. If
> > .apply is called with a new set of parameters the currently running
> > period with the old values is expected to complete before the new values
> > take effect.
> 
> You pointed it, indeed; but I won't change it until I can verify that the
> behaviour is correct (which does not seem to be the case even if I leave
> this bit cleared). Besides, this is the TCU patchset, fixes and patches
> unrelated to the TCU don't belong here.

So abrupt mode was already used before? Then maybe note in a comment
that this is wrong but kept for now as this change is only refactoring
without changing behaviour.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

  reply	other threads:[~2019-01-05 21:18 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-27 18:12 [PATCH v9 00/27] Ingenic TCU patchset v9 Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 01/27] dt-bindings: ingenic: Add DT bindings for TCU clocks Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 02/27] doc: Add doc for the Ingenic TCU hardware Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 03/27] dt-bindings: Add doc for the Ingenic TCU drivers Paul Cercueil
2018-12-28 21:48   ` Rob Herring
2018-12-27 18:12 ` [PATCH v9 04/27] clocksource: Add a new timer-ingenic driver Paul Cercueil
2019-02-25 15:55   ` Daniel Lezcano
2019-02-25 22:59     ` Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 05/27] clocksource: Add driver for the Ingenic JZ47xx OST Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 06/27] MAINTAINERS: Add myself as maintainer for Ingenic TCU drivers Paul Cercueil
2018-12-27 18:12 ` [PATCH v9 07/27] watchdog: jz4740: Use WDT clock provided by TCU driver Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 08/27] watchdog: jz4740: Use regmap " Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 09/27] watchdog: jz4740: Avoid starting watchdog in set_timeout Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 10/27] watchdog: jz4740: Drop dependency on MACH_JZ47xx, use COMPILE_TEST Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 11/27] pwm: jz4740: Apply configuration atomically Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 12/27] pwm: jz4740: Use regmap from TCU driver Paul Cercueil
2019-01-05 19:42   ` Uwe Kleine-König
2019-01-05 20:46     ` Paul Cercueil
2019-01-05 21:18       ` Uwe Kleine-König [this message]
2018-12-27 18:13 ` [PATCH v9 13/27] pwm: jz4740: Use clocks " Paul Cercueil
2019-01-05 19:45   ` Uwe Kleine-König
2019-01-05 20:52     ` Paul Cercueil
2019-01-05 21:19       ` Uwe Kleine-König
2018-12-27 18:13 ` [PATCH v9 14/27] pwm: jz4740: Improve algorithm of clock calculation Paul Cercueil
2019-01-05 19:57   ` Uwe Kleine-König
2019-01-05 21:05     ` Paul Cercueil
2019-01-05 21:27       ` Uwe Kleine-König
2019-01-10 14:04         ` Paul Cercueil
2019-02-23  1:17           ` Paul Cercueil
2019-02-28 18:42             ` Stephen Boyd
2018-12-27 18:13 ` [PATCH v9 15/27] pwm: jz4740: Allow selection of PWM channels 0 and 1 Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 16/27] pwm: jz4740: Drop dependency on MACH_INGENIC, use COMPILE_TEST Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 17/27] pwm: jz4740: Remove unused devicetree compatible strings Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 18/27] clk: jz4740: Add TCU clock Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 19/27] MIPS: Kconfig: Select TCU timer driver when MACH_INGENIC is set Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 20/27] MIPS: jz4740: Add DTS nodes for the TCU drivers Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 21/27] MIPS: qi_lb60: Move PWM devices to devicetree Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 22/27] MIPS: qi_lb60: Reduce system timer and clocksource to 750 kHz Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 23/27] MIPS: CI20: Reduce system timer to 3 MHz Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 24/27] MIPS: CI20: defconfig: enable OST driver Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 25/27] MIPS: GCW0: Reduce system timer to 750 kHz Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 26/27] MIPS: GCW0: defconfig: Enable OST, watchdog, PWM drivers Paul Cercueil
2018-12-27 18:13 ` [PATCH v9 27/27] MIPS: jz4740: Drop obsolete code Paul Cercueil

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