From: Thierry Reding <thierry.reding@gmail.com>
To: "Lothar Waßmann" <LW@karo-electronics.de>
Cc: "Vokáč Michal" <Michal.Vokac@ysoft.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Mark Rutland" <mark.rutland@arm.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-pwm@vger.kernel.org" <linux-pwm@vger.kernel.org>,
"Lukasz Majewski" <l.majewski@majess.pl>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Rob Herring" <robh+dt@kernel.org>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
"Fabio Estevam" <fabio.estevam@nxp.com>,
"Linus Walleij" <linus.walleij@linaro.org>,
"viresh kumar" <viresh.kumar@linaro.org>
Subject: Re: [RCF PATCH,v2,2/2] pwm: imx: Configure output to GPIO in disabled state
Date: Mon, 26 Nov 2018 14:34:41 +0100 [thread overview]
Message-ID: <20181126133441.GA19710@ulmo> (raw)
In-Reply-To: <20181126132316.541a4131@ipc1.ka-ro>
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On Mon, Nov 26, 2018 at 01:23:16PM +0100, Lothar Waßmann wrote:
> Thierry Reding <thierry.reding@gmail.com> wrote:
>
> > On Fri, Nov 23, 2018 at 03:15:11PM +0000, Vokáč Michal wrote:
> > > On 22.11.2018 20:03, Uwe Kleine-König wrote:
> > > > On Thu, Nov 22, 2018 at 04:46:39PM +0000, Vokáč Michal wrote:
> > > >> On 22.11.2018 17:23, Uwe Kleine-König wrote:
> > > >>> On Thu, Nov 22, 2018 at 03:42:14PM +0000, Vokáč Michal wrote:
> > > >>>> On 16.11.2018 09:25, Uwe Kleine-König wrote:
> > > >>>>> On Fri, Nov 16, 2018 at 08:34:30AM +0100, Lothar Waßmann wrote:
> > > >>>>>> No. You can disable the output driver via pinctrl, so that only the
> > > >>>>>> selected pull-up/down is relevant. The pin function and GPIO register
> > > >>>>>> settings don't matter at all in this case.
> > > >>>>
> > > >>>> Lothar, please can you be more specific how would you do that? IFAIK the
> > > >>>> pull-up/down internal resistors have effect only if the pin is configured
> > > >>>> as GPIO *input* (on i.MX6 at least). See the TRM, 29.4.2.2 Output driver:
> > > >>>>
> > > >>>> "Internal pull-up, pull-down resistors, and pad keeper are disabled in
> > > >>>> output mode."
> > > >
> > > > This would mean you'd have to rely on an external pull up for your use
> > > > case. I wouldn't be surprised however if DSE=0 wouldn't count as "output
> > > > mode". Given the reliability of NXP documentation I wouldn't bet neither
> > > > on one nor the other possibility.
> > >
> > > Yeah, the NXP documentation sometimes does not really match reality.
> > > My use case is based on the fact that I configure the pin as input in
> > > the driver. Then it works just fine.
> > >
> > > >>> So I'd expect this to really work on i.MX6 but not the earlier SoCs
> > > >>> without a gpio specifier.
> > > >>
> > > >> Maybe you would expect it to work but I already tested and measured
> > > >> that weeks ago ;) It did not work.
> > > >
> > > > Which pin/gpio do we talk about? Which i.MX6 variant did you test this
> > > > on? (Assuming i.MX6D or i.MX6Q and PAD_DISP0_DATA09, did you try setting
> > > >
> > > > IOMUXC_SW_MUX_CTL_PAD_DISP0_DATA09 (0x020E0194) = 0x00000005
> > > > IOMUXC_SW_PAD_CTL_PAD_DISP0_DATA09 (0x020E04A8) = 0x0000b080
> > > >
> > > > and then play with GPIO 4.30 direction and output value?)
> > >
> > > My test setup is as follows:
> > > - SoC is i.MX6DL or i.MX6S - I have three board variants in total.
> > > - Pin used for PWM/GPIO is PAD_GPIO9.
> > > - The pin is not connected to any circuit. Just a test point.
> > > - pinctrl setup in DT:
> > > - for "pwm":
> > > - fsl,pins = <MX6QDL_PAD_GPIO_9__PWM1_OUT 0x8>
> > > - IOMUXC_SW_MUX_CTL_PAD_GPIO09 = 0x00000004
> > > - IOMUXC_SW_PAD_CTL_PAD_GPIO09 = 0x00000008
> > >
> > > - for "gpio":
> > > - fsl,pins = <MX6QDL_PAD_GPIO_9__GPIO1_IO09 0xb000>
> > > - IOMUXC_SW_MUX_CTL_PAD_GPIO09 = 0x00000005
> > > - IOMUXC_SW_PAD_CTL_PAD_GPIO09 = 0x0000b000
> >
> > Does it help if you additionally set the ODE bit (bit 11) here?
> >
> That only helps to NOT actively pulling the pin HIGH, but the opposite
> is what is needed here.
From the description in the reference manual it sounded like the ODE
would avoid the pin from actively being driven anywhere if configured as
output. So I was hoping that in conjunction with the pull-up it would
actually do the right thing.
Thierry
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next prev parent reply other threads:[~2018-11-26 13:34 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-10 9:33 [RCF PATCH v2 0/2] pwm: imx: Configure output to GPIO in disabled state Vokáč Michal
2018-10-10 9:33 ` [RCF PATCH v2 1/2] dt-bindings: pwm: imx: Allow switching PWM output between PWM and GPIO Vokáč Michal
2018-10-10 13:39 ` Thierry Reding
2018-10-29 15:52 ` Vokáč Michal
2018-10-10 9:33 ` [RCF PATCH v2 2/2] pwm: imx: Configure output to GPIO in disabled state Vokáč Michal
2018-10-12 8:57 ` [RCF PATCH,v2,2/2] " Uwe Kleine-König
2018-10-12 15:04 ` Vokáč Michal
2018-10-12 15:54 ` Thierry Reding
2018-10-12 16:08 ` Uwe Kleine-König
2018-10-14 20:24 ` Uwe Kleine-König
2018-10-15 8:45 ` Thierry Reding
2018-10-29 15:55 ` Vokáč Michal
2018-10-29 15:54 ` Vokáč Michal
2018-11-07 9:33 ` Uwe Kleine-König
2018-11-07 13:32 ` Vokáč Michal
2018-11-07 15:01 ` Uwe Kleine-König
2018-11-08 15:21 ` Vokáč Michal
2018-11-08 19:18 ` Uwe Kleine-König
2018-11-09 14:24 ` Vokáč Michal
2018-11-09 16:55 ` Uwe Kleine-König
2018-11-14 9:09 ` Uwe Kleine-König
2018-11-14 11:34 ` Thierry Reding
2018-11-14 21:51 ` Uwe Kleine-König
2018-11-15 15:25 ` Thierry Reding
2018-11-15 20:37 ` Uwe Kleine-König
2018-11-16 7:34 ` Lothar Waßmann
2018-11-16 8:25 ` Uwe Kleine-König
2018-11-22 15:42 ` Vokáč Michal
2018-11-22 16:23 ` Uwe Kleine-König
2018-11-22 16:46 ` Vokáč Michal
2018-11-22 19:03 ` Uwe Kleine-König
2018-11-23 15:15 ` Vokáč Michal
2018-11-25 20:56 ` Uwe Kleine-König
2018-11-26 9:11 ` Lothar Waßmann
2018-11-26 9:18 ` Uwe Kleine-König
2018-11-26 10:03 ` Lothar Waßmann
2018-11-26 11:51 ` Thierry Reding
2018-11-26 12:23 ` Lothar Waßmann
2018-11-26 13:34 ` Thierry Reding [this message]
2018-11-26 15:50 ` Vokáč Michal
2018-11-16 9:51 ` Thierry Reding
2018-11-16 10:39 ` Uwe Kleine-König
2018-11-16 11:56 ` Lothar Waßmann
2018-11-18 11:30 ` Uwe Kleine-König
2018-11-16 12:24 ` Thierry Reding
2018-11-18 20:08 ` Uwe Kleine-König
2018-11-19 8:48 ` Uwe Kleine-König
2018-11-22 15:03 ` Thierry Reding
2018-11-22 16:17 ` Uwe Kleine-König
2018-11-20 13:14 ` Vokáč Michal
2018-11-20 16:54 ` Uwe Kleine-König
2018-11-22 14:23 ` Vokáč Michal
2018-11-19 7:44 ` Linus Walleij
2018-11-19 8:32 ` Uwe Kleine-König
2018-11-20 8:35 ` Linus Walleij
2018-11-20 9:16 ` Viresh Kumar
2018-11-20 9:53 ` Uwe Kleine-König
2018-11-14 11:14 ` Thierry Reding
2018-10-12 16:00 ` [RCF PATCH v2 2/2] " Thierry Reding
2018-10-29 15:53 ` Vokáč Michal
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