From: Jonathan Richardson <jonathar@broadcom.com> To: Tim Kryger <tim.kryger@gmail.com> Cc: Scott Branden <sbranden@broadcom.com>, Arun Ramamurthy <arun.ramamurthy@broadcom.com>, Thierry Reding <thierry.reding@gmail.com>, Ray Jui <rjui@broadcom.com>, <bcm-kernel-feedback-list@broadcom.com>, "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>, <linux-pwm@vger.kernel.org> Subject: Re: [PATCH v2 1/2] pwm: kona: Fix incorrect enable, config, and disable procedures Date: Tue, 16 Dec 2014 11:36:58 -0800 [thread overview] Message-ID: <549089DA.9070405@broadcom.com> (raw) In-Reply-To: <CAD7vxxJ2++PNteSZ+F5epvPW_nrrSZT9pja325pmLVhq_MHL0w@mail.gmail.com> On 14-12-14 11:18 PM, Tim Kryger wrote: > On Wed, Dec 10, 2014 at 5:07 PM, Jonathan Richardson > <jonathar@broadcom.com> wrote: > >> If config is called when the pwm is disabled and there is nothing to do, >> the while loop to calculate duty cycle and period doesn't need to be >> done. The function now just returns if the pwm state is disabled. > > It doesn't take long to figure out whether the duty and period are achievable. > > If the caller specifies bad settings, why not return an error immediately? Sorry, not sure what you're suggesting here. It's returning as soon as it can isn't it? Nothing changed in the way the period and duty cycle were calculated and checked in the while loop. > >> @@ -207,13 +240,23 @@ static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm) >> { >> struct kona_pwmc *kp = to_kona_pwmc(chip); >> unsigned int chan = pwm->hwpwm; >> + unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET); >> + >> + /* Set smooth type to 0 and disable */ >> + value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan)); >> + value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan)); >> + writel(value, kp->base + PWM_CONTROL_OFFSET); >> >> /* Simulate a disable by configuring for zero duty */ >> writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); >> - kona_pwmc_apply_settings(kp, chan); >> + writel(0, kp->base + PERIOD_COUNT_OFFSET(chan)); >> >> - /* Wait for waveform to settle before gating off the clock */ >> - ndelay(400); >> + /* Set prescale to 0 for this channel */ >> + value = readl(kp->base + PRESCALE_OFFSET); >> + value &= ~PRESCALE_MASK(chan); >> + writel(value, kp->base + PRESCALE_OFFSET); >> + >> + kona_pwmc_apply_settings(kp, chan); >> >> clk_disable_unprepare(kp->clk); >> } > > I've mentioned this before but I will say it again, when the smooth > and trigger bit are both low, the output is constant high. > > If you look at the PWM output on a scope you will see it go high for > 400 ns during your disable even if the duty prior to the disable was > zero. > > How are you testing your proposed changes? > I see what you mean now and verified it. For a smooth transition even on disable the smooth bit should be set high, not low. It's the same procedure as in config. Setting the bit high instead of low gets rid of the 400ns transition high. I can make this change. > Thanks, > Tim Kryger >
WARNING: multiple messages have this Message-ID (diff)
From: Jonathan Richardson <jonathar@broadcom.com> To: Tim Kryger <tim.kryger@gmail.com> Cc: Scott Branden <sbranden@broadcom.com>, Arun Ramamurthy <arun.ramamurthy@broadcom.com>, Thierry Reding <thierry.reding@gmail.com>, Ray Jui <rjui@broadcom.com>, bcm-kernel-feedback-list@broadcom.com, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-pwm@vger.kernel.org Subject: Re: [PATCH v2 1/2] pwm: kona: Fix incorrect enable, config, and disable procedures Date: Tue, 16 Dec 2014 11:36:58 -0800 [thread overview] Message-ID: <549089DA.9070405@broadcom.com> (raw) In-Reply-To: <CAD7vxxJ2++PNteSZ+F5epvPW_nrrSZT9pja325pmLVhq_MHL0w@mail.gmail.com> On 14-12-14 11:18 PM, Tim Kryger wrote: > On Wed, Dec 10, 2014 at 5:07 PM, Jonathan Richardson > <jonathar@broadcom.com> wrote: > >> If config is called when the pwm is disabled and there is nothing to do, >> the while loop to calculate duty cycle and period doesn't need to be >> done. The function now just returns if the pwm state is disabled. > > It doesn't take long to figure out whether the duty and period are achievable. > > If the caller specifies bad settings, why not return an error immediately? Sorry, not sure what you're suggesting here. It's returning as soon as it can isn't it? Nothing changed in the way the period and duty cycle were calculated and checked in the while loop. > >> @@ -207,13 +240,23 @@ static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm) >> { >> struct kona_pwmc *kp = to_kona_pwmc(chip); >> unsigned int chan = pwm->hwpwm; >> + unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET); >> + >> + /* Set smooth type to 0 and disable */ >> + value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan)); >> + value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan)); >> + writel(value, kp->base + PWM_CONTROL_OFFSET); >> >> /* Simulate a disable by configuring for zero duty */ >> writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); >> - kona_pwmc_apply_settings(kp, chan); >> + writel(0, kp->base + PERIOD_COUNT_OFFSET(chan)); >> >> - /* Wait for waveform to settle before gating off the clock */ >> - ndelay(400); >> + /* Set prescale to 0 for this channel */ >> + value = readl(kp->base + PRESCALE_OFFSET); >> + value &= ~PRESCALE_MASK(chan); >> + writel(value, kp->base + PRESCALE_OFFSET); >> + >> + kona_pwmc_apply_settings(kp, chan); >> >> clk_disable_unprepare(kp->clk); >> } > > I've mentioned this before but I will say it again, when the smooth > and trigger bit are both low, the output is constant high. > > If you look at the PWM output on a scope you will see it go high for > 400 ns during your disable even if the duty prior to the disable was > zero. > > How are you testing your proposed changes? > I see what you mean now and verified it. For a smooth transition even on disable the smooth bit should be set high, not low. It's the same procedure as in config. Setting the bit high instead of low gets rid of the 400ns transition high. I can make this change. > Thanks, > Tim Kryger >
next prev parent reply other threads:[~2014-12-16 19:36 UTC|newest] Thread overview: 222+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <Jonathan Richardson <jonathar@broadcom.com> 2014-09-16 19:58 ` [PATCH 0/6] Add initial support for Broadcom Cygnus SoC Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` [PATCH 1/6] ARM: cygnus: Initial " Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-17 0:00 ` Mark Rutland 2014-09-17 0:00 ` Mark Rutland 2014-09-17 0:00 ` Mark Rutland 2014-09-18 23:33 ` Jonathan Richardson 2014-09-18 23:33 ` Jonathan Richardson 2014-09-18 23:33 ` Jonathan Richardson 2014-09-16 19:58 ` [PATCH 2/6] clk: Clock driver " Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-17 0:47 ` Mark Rutland 2014-09-17 0:47 ` Mark Rutland 2014-09-17 0:47 ` Mark Rutland 2014-09-18 23:43 ` Jonathan Richardson 2014-09-18 23:43 ` Jonathan Richardson 2014-09-18 23:43 ` Jonathan Richardson 2014-09-16 19:58 ` [PATCH 3/6] dt-bindings: Document Broadcom Cygnus SoC and clock driver Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` [PATCH 4/6] ARM: dts: Enable Broadcom Cygnus SoC Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` [PATCH 5/6] ARM: cygnus defconfig : Initial defconfig for " Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` [PATCH 6/6] MAINTAINERS: Entry for Cygnus/iproc arm architecture and clock drivers Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-16 19:58 ` Jonathan Richardson 2014-09-18 22:31 ` [PATCH 0/6] Add initial support for Broadcom Cygnus SoC Hauke Mehrtens 2014-09-18 22:31 ` Hauke Mehrtens 2014-09-18 22:31 ` Hauke Mehrtens 2014-09-18 22:39 ` Florian Fainelli 2014-09-18 22:39 ` Florian Fainelli 2014-09-18 22:54 ` Hauke Mehrtens 2014-09-18 22:54 ` Hauke Mehrtens 2014-09-18 22:54 ` Hauke Mehrtens 2014-09-19 0:58 ` Scott Branden 2014-09-19 0:58 ` Scott Branden 2014-09-23 21:17 ` [PATCH v2 " Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` [PATCH v2 1/6] ARM: cygnus: Initial " Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` [PATCH v2 2/6] clk: Clock driver " Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` [PATCH v2 3/6] dt-bindings: Document Broadcom Cygnus SoC and clock driver Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` [PATCH v2 4/6] ARM: dts: Enable Broadcom Cygnus SoC Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` [PATCH v2 5/6] ARM: cygnus defconfig : Initial defconfig for " Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` [PATCH v2 6/6] MAINTAINERS: Entry for Cygnus/iproc arm architecture and clock drivers Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-23 21:17 ` Jonathan Richardson 2014-09-25 21:04 ` [PATCH v2 0/6] Add initial support for Broadcom Cygnus SoC Scott Branden 2014-09-25 21:04 ` Scott Branden 2014-09-25 21:04 ` Scott Branden 2014-09-25 21:22 ` Florian Fainelli 2014-09-25 21:22 ` Florian Fainelli 2014-09-25 21:22 ` Florian Fainelli 2014-09-26 0:14 ` Florian Fainelli 2014-09-26 0:14 ` Florian Fainelli 2014-09-26 0:14 ` Florian Fainelli 2014-09-26 0:28 ` Jonathan Richardson 2014-09-26 0:28 ` Jonathan Richardson 2014-09-26 0:28 ` Jonathan Richardson 2014-09-26 0:34 ` Florian Fainelli 2014-09-26 0:34 ` Florian Fainelli 2014-09-26 0:34 ` Florian Fainelli 2014-12-11 1:07 ` [PATCH v2 1/2] pwm: kona: Fix incorrect enable, config, and disable procedures Jonathan Richardson 2014-12-11 1:07 ` Jonathan Richardson 2014-12-11 1:07 ` [PATCH v2 2/2] pwm: kona: Remove setting default smooth type and polarity for all channels Jonathan Richardson 2014-12-11 1:07 ` Jonathan Richardson 2014-12-15 7:18 ` [PATCH v2 1/2] pwm: kona: Fix incorrect enable, config, and disable procedures Tim Kryger 2014-12-16 19:36 ` Jonathan Richardson [this message] 2014-12-16 19:36 ` Jonathan Richardson 2014-12-17 18:46 ` [PATCH v3 " Jonathan Richardson 2014-12-17 18:46 ` Jonathan Richardson 2014-12-17 18:46 ` [PATCH v3 2/2] pwm: kona: Remove setting default smooth type and polarity for all channels Jonathan Richardson 2014-12-17 18:46 ` Jonathan Richardson 2014-12-20 22:38 ` [PATCH v3 1/2] pwm: kona: Fix incorrect enable, config, and disable procedures Tim Kryger 2014-12-22 22:49 ` Jonathan Richardson 2014-12-22 22:49 ` Jonathan Richardson 2014-12-18 1:59 ` [PATCH 0/2] Add support for Broadcom iProc touchscreen Jonathan Richardson 2014-12-18 1:59 ` Jonathan Richardson 2014-12-18 1:59 ` Jonathan Richardson 2014-12-18 1:59 ` [PATCH 1/2] Input: touchscreen-iproc: Add Broadcom iProc touchscreen driver Jonathan Richardson 2014-12-18 1:59 ` Jonathan Richardson 2014-12-18 1:59 ` Jonathan Richardson 2014-12-18 2:14 ` Joe Perches 2014-12-18 2:14 ` Joe Perches 2014-12-19 19:51 ` Jonathan Richardson 2014-12-19 19:51 ` Jonathan Richardson 2014-12-19 19:51 ` Jonathan Richardson 2014-12-19 19:56 ` Dmitry Torokhov 2014-12-19 19:56 ` Dmitry Torokhov 2014-12-18 1:59 ` [PATCH 2/2] Input: touchscreen-iproc: add device tree bindings Jonathan Richardson 2014-12-18 1:59 ` Jonathan Richardson 2014-12-18 1:59 ` Jonathan Richardson 2014-12-19 22:17 ` [PATCH v2 0/2] Add support for Broadcom iProc touchscreen Jonathan Richardson 2014-12-19 22:17 ` Jonathan Richardson 2014-12-19 22:17 ` Jonathan Richardson 2014-12-19 22:17 ` [PATCH v2 1/2] Input: touchscreen-iproc: Add Broadcom iProc touchscreen driver Jonathan Richardson 2014-12-19 22:17 ` Jonathan Richardson 2014-12-19 22:17 ` Jonathan Richardson 2014-12-19 22:26 ` Joe Perches 2014-12-19 22:26 ` Joe Perches 2014-12-19 22:26 ` Joe Perches 2014-12-19 23:03 ` Jonathan Richardson 2014-12-19 23:03 ` Jonathan Richardson 2014-12-19 23:03 ` Jonathan Richardson 2015-01-01 0:55 ` Jonathan Richardson 2015-01-01 0:55 ` Jonathan Richardson 2015-01-01 0:55 ` Jonathan Richardson 2015-01-15 1:08 ` Florian Fainelli 2015-01-15 1:08 ` Florian Fainelli 2015-01-15 19:19 ` Jonathan Richardson 2015-01-15 19:19 ` Jonathan Richardson 2015-01-15 19:19 ` Jonathan Richardson 2015-01-15 1:02 ` Dmitry Torokhov 2015-01-15 1:02 ` Dmitry Torokhov 2015-01-15 5:44 ` Scott Branden 2015-01-15 5:44 ` Scott Branden 2015-01-15 5:44 ` Scott Branden 2015-01-15 6:07 ` Dmitry Torokhov 2015-01-15 6:07 ` Dmitry Torokhov 2015-01-15 19:51 ` Jonathan Richardson 2015-01-15 19:51 ` Jonathan Richardson 2015-01-15 19:51 ` Jonathan Richardson 2015-02-11 18:45 ` Jonathan Richardson 2015-02-11 18:45 ` Jonathan Richardson 2015-02-11 18:45 ` Jonathan Richardson 2015-02-24 23:18 ` Dmitry Torokhov 2015-02-24 23:18 ` Dmitry Torokhov 2015-02-24 23:18 ` Dmitry Torokhov 2015-02-27 1:02 ` Jonathan Richardson 2015-02-27 1:02 ` Jonathan Richardson 2015-02-27 1:02 ` Jonathan Richardson 2015-02-24 23:29 ` Dmitry Torokhov 2015-02-24 23:29 ` Dmitry Torokhov 2015-02-24 23:29 ` Dmitry Torokhov 2015-03-02 19:13 ` Jonathan Richardson 2015-03-02 19:13 ` Jonathan Richardson 2015-03-02 19:13 ` Jonathan Richardson 2014-12-19 22:17 ` [PATCH v2 2/2] Input: touchscreen-iproc: add device tree bindings Jonathan Richardson 2014-12-19 22:17 ` Jonathan Richardson 2014-12-19 22:17 ` Jonathan Richardson 2014-12-30 22:43 ` [PATCH v4 0/3] Fix bugs in kona pwm driver and pwm core Jonathan Richardson 2014-12-30 22:43 ` Jonathan Richardson 2014-12-30 22:43 ` [PATCH v4 1/3] pwm: kona: Fix incorrect config, disable, and polarity procedures Jonathan Richardson 2014-12-30 22:43 ` Jonathan Richardson 2014-12-30 22:43 ` [PATCH v4 2/3] pwm: kona: Remove setting default smooth type and polarity for all channels Jonathan Richardson 2014-12-30 22:43 ` Jonathan Richardson 2015-01-05 1:12 ` Tim Kryger 2015-01-05 1:33 ` Tim Kryger 2014-12-30 22:43 ` [PATCH v4 3/3] pwm: core: Set enable state properly on failed call to enable Jonathan Richardson 2014-12-30 22:43 ` Jonathan Richardson 2015-01-07 19:42 ` [PATCH v5 0/2] Fix bugs in kona pwm driver and pwm core Jonathan Richardson 2015-01-07 19:42 ` Jonathan Richardson 2015-01-07 19:42 ` [PATCH v5 1/2] pwm: kona: Fix incorrect config, disable, and polarity procedures Jonathan Richardson 2015-01-07 19:42 ` Jonathan Richardson 2015-01-07 19:42 ` [PATCH v5 2/2] pwm: core: Set enable state properly on failed call to enable Jonathan Richardson 2015-01-07 19:42 ` Jonathan Richardson 2015-02-11 23:59 ` Dmitry Torokhov 2015-02-24 19:13 ` [PATCH 0/1] Enable Broadcom Cygnus BCM958305K Jonathan Richardson 2015-02-24 19:13 ` Jonathan Richardson 2015-02-24 19:13 ` Jonathan Richardson 2015-02-24 19:13 ` [PATCH 1/1] ARM: dts: " Jonathan Richardson 2015-02-24 19:13 ` Jonathan Richardson 2015-02-24 19:13 ` Jonathan Richardson 2015-02-25 19:04 ` [PATCH 0/1] Synopsis 8250 serial port driver fix Jonathan Richardson 2015-02-25 19:04 ` Jonathan Richardson 2015-02-25 19:04 ` [PATCH 1/1] serial: 8250_dw: Fix get_mctrl behaviour Jonathan Richardson 2015-02-25 19:04 ` Jonathan Richardson 2015-02-25 19:21 ` Arnd Bergmann 2015-02-25 20:00 ` Jonathan Richardson 2015-02-25 20:00 ` Jonathan Richardson 2015-02-25 20:07 ` Arnd Bergmann 2015-02-27 0:35 ` [PATCH v2 0/1] Synopsis 8250 serial port driver fix Jonathan Richardson 2015-02-27 0:35 ` Jonathan Richardson 2015-02-27 0:35 ` [PATCH v2 1/1] serial: 8250_dw: Fix get_mctrl behaviour Jonathan Richardson 2015-02-27 0:35 ` Jonathan Richardson 2015-03-09 18:40 ` Dmitry Torokhov 2015-03-09 18:51 ` Jonathan Richardson 2015-03-09 18:51 ` Jonathan Richardson 2015-03-02 22:41 ` [PATCH RESEND 0/1] Enable Broadcom Cygnus BCM958305K Jonathan Richardson 2015-03-02 22:41 ` Jonathan Richardson 2015-03-02 22:41 ` Jonathan Richardson 2015-03-02 22:41 ` [PATCH RESEND 1/1] ARM: dts: " Jonathan Richardson 2015-03-02 22:41 ` Jonathan Richardson 2015-03-02 22:41 ` Jonathan Richardson 2015-03-02 23:45 ` Florian Fainelli 2015-03-02 23:45 ` Florian Fainelli 2015-03-02 23:45 ` Florian Fainelli 2015-03-11 1:17 ` [PATCH v3 0/2] Add support for Broadcom iProc touchscreen Jonathan Richardson 2015-03-11 1:17 ` Jonathan Richardson 2015-03-11 1:17 ` [PATCH v3 1/2] Input: touchscreen-iproc: Add Broadcom iProc touchscreen driver Jonathan Richardson 2015-03-11 1:17 ` Jonathan Richardson 2015-03-11 9:46 ` Paul Bolle 2015-03-11 17:05 ` Jonathan Richardson 2015-03-11 17:05 ` Jonathan Richardson 2015-03-11 1:17 ` [PATCH v3 2/2] Input: touchscreen-iproc: add device tree bindings Jonathan Richardson 2015-03-11 1:17 ` Jonathan Richardson 2015-03-12 17:45 ` [PATCH v4 0/2] Add support for Broadcom iProc touchscreen Jonathan Richardson 2015-03-12 17:45 ` Jonathan Richardson 2015-03-12 17:45 ` [PATCH v4 1/2] Input: touchscreen-iproc: Add Broadcom iProc touchscreen driver Jonathan Richardson 2015-03-12 17:45 ` Jonathan Richardson 2015-03-12 17:59 ` Joe Perches 2015-03-12 22:44 ` Jonathan Richardson 2015-03-12 22:44 ` Jonathan Richardson 2015-03-12 17:45 ` [PATCH v4 2/2] Input: touchscreen-iproc: add device tree bindings Jonathan Richardson 2015-03-12 17:45 ` Jonathan Richardson
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