lkml.org 
[lkml]   [2018]   [Dec]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH v3 2/2] pwm: imx: Configure output to GPIO in disabled state
On Thu, Dec 06, 2018 at 03:37:55PM +0000, Vokáč Michal wrote:
> On 6.12.2018 14:59, Uwe Kleine-König wrote:
> > On Thu, Dec 06, 2018 at 01:41:31PM +0000, Vokáč Michal wrote:
> >> +{
> >> + imx_chip->pinctrl = devm_pinctrl_get(&pdev->dev);
> >> + if (IS_ERR(imx_chip->pinctrl)) {
> >> + dev_dbg(&pdev->dev, "can not get pinctrl\n");
> >> + return PTR_ERR(imx_chip->pinctrl);
> >> + }
> >> +
> >> + imx_chip->pinctrl_pins_pwm = pinctrl_lookup_state(imx_chip->pinctrl,
> >> + "pwm");
> >> + imx_chip->pinctrl_pins_gpio = pinctrl_lookup_state(imx_chip->pinctrl,
> >> + "gpio");
> >> + imx_chip->pwm_gpiod = devm_gpiod_get_optional(&pdev->dev, "pwm",
> >> + GPIOD_IN);
> >> +
> >> + if (PTR_ERR(imx_chip->pwm_gpiod) == -EPROBE_DEFER) {
> >> + return -EPROBE_DEFER;
> >> + } else if (IS_ERR(imx_chip->pwm_gpiod) ||
> >> + IS_ERR(imx_chip->pinctrl_pins_pwm) ||
> >> + IS_ERR(imx_chip->pinctrl_pins_gpio)) {
> >> + dev_dbg(&pdev->dev, "PWM pinctrl information incomplete\n");
> >> + devm_pinctrl_put(imx_chip->pinctrl);
> >> + imx_chip->pinctrl = NULL;
> >
> > Can it happen, that pinctrl_pins_pwm is PTR_ERR(-EPROBE_DEFER)?
>
> No. The pinctrl_lookup_state either returns pointer to the pinctrl state
> or ERR_PTR(-ENODEV). But I do not explicitly test the pinctrl_pins_pwm
> for PTR_ERR(-EPROBE_DEFER), or do I?

You don't, I just wondered if this could happen and the function should
return -EPROBE_DEFER in this case, too.

> > Maybe you only want to ignore PTR_ERR(-ENODEV) and for example propagate
> > -EIO? I think you want to put the gpio if the failure is because there
> > is a pinctrl related error.
>
> I think that is what I am doing. In case the GPIO is not ready the probe
> is deferred. In case of any other error with the GPIO or pinctrl failure
> I put the pinctrl. Or maybe I do not really understand what you mean.

Yes, you put the pinctrl, but not the GPIO. I.e. you're not undoing
devm_gpiod_get_optional(). Maybe only do this if the pinctrl stuff
succeeded to not touch the GPIO if it won't be used?

> > ISTR that there was a patch that implements get_state for imx. Is there
> > a dependency on that one? Otherwise the state returned by
> > pwm_get_state() might not be what is actually configured.
>
> No, it should be independent. One can go without the other. I tested all
> three combinations (mainline with .get_state, mainline with this series,
> mainline with .get_state AND this series) and got the expected results.
> Without the .get_state() patch the core always returns the default which
> is disabled state so the gpio pinctrl state is selected in probe.

Without .get_state it won't be possible to smoothly take over a running
PWM. It doesn't hurt if the PWM isn't running though. Still I'd like to
see the .get_state patch to go in first to not get this (admittedly
small) regression.

> > Do you know if this is required for the old i.MX pwm, e.g. on i.MX21?
> > I ask because of https://patchwork.ozlabs.org/patch/1000071/
>
> Yep, I am aware of that patch. IMHO this is not needed for the v1 on
> older i.MX SoCs but I do not have a hands-on experience with those.

OK. If you agree with my split and as you have to rework your patch
anyhow: Would you mind to rebase on top of my patch series? (Unless
Thierry disagrees with my patches, but unfortunately he didn't comment
yet.)

Best regards
Uwe

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

\
 
 \ /
  Last update: 2018-12-06 17:16    [W:0.066 / U:8.696 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site