linux-kernel - Re: [PATCH v4 3/6] usb: ohci-da8xx: disable the regulator if the overcurrent irq fired

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Message-ID: <CAMRc=MeCxEM+q2m55_2LV6C9kLxJqZqtQytNrsdO5AiV6rT8gA@mail.gmail.com>
Date:   Fri, 12 Apr 2019 14:12:36 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Sekhar Nori <nsekhar@...com>
Cc:     Kevin Hilman <khilman@...nel.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-usb@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH v4 3/6] usb: ohci-da8xx: disable the regulator if the
 overcurrent irq fired

pt., 12 kwi 2019 o 12:39 Sekhar Nori <nsekhar@...com> napisał(a):
>
> Hi Bartosz,
>
> On 11/04/19 3:00 PM, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> >
> > Historically the power supply management in this driver has been handled
> > in two separate places in parallel. Device-tree users simply defined an
> > appropriate regulator, while two boards with no DT support (da830-evm and
> > omapl138-hawk) passed functions defined in their respective board files
> > over platform data. These functions simply used legacy GPIO calls to
> > watch the oc GPIO for interrupts and disable the vbus GPIO when the irq
> > fires.
> >
> > Commit d193abf1c913 ("usb: ohci-da8xx: add vbus and overcurrent gpios")
> > updated these GPIO calls to the modern API and moved them inside the
> > driver.
> >
> > This however is not the optimal solution for the vbus GPIO which should
> > be modeled as a fixed regulator that can be controlled with a GPIO.
> >
> > In order to keep the overcurrent protection available once we move the
> > board files to using fixed regulators we need to disable the enable_reg
> > regulator when the overcurrent indicator interrupt fires. Since we
> > cannot call regulator_disable() from interrupt context, we need to
> > switch to using a oneshot threaded interrupt.
> >
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
>
> I thought a bit on whether it makes sense to merge this patch into 6/6
> since that is modifying some code you introduce here. But I think its
> probably better to keep it separate like you have it now.
>
> 6/6 is about dropping support for vbus gpio, where as here you are
> letting regulator be used for handing overcurrent detected using oci gpio.
>
> Having it separate makes it possible to revert dropping support for vbus
> gpio while keeping this functionality ;)
>

These two changes were together in v1, but I too think that having it
separate keeps the series bisectable.

Bart

> > -static irqreturn_t ohci_da8xx_oc_handler(int irq, void *data)
> > +static irqreturn_t ohci_da8xx_oc_thread(int irq, void *data)
> >  {
> >       struct da8xx_ohci_hcd *da8xx_ohci = data;
> > +     struct device *dev = da8xx_ohci->hcd->self.controller;
> > +     int ret;
> >
> > -     if (gpiod_get_value(da8xx_ohci->oc_gpio))
> > -             gpiod_set_value(da8xx_ohci->vbus_gpio, 0);
> > +     if (gpiod_get_value_cansleep(da8xx_ohci->oc_gpio)) {
> > +             if (da8xx_ohci->vbus_gpio) {
> > +                     gpiod_set_value_cansleep(da8xx_ohci->vbus_gpio, 0);
> > +             } else if (da8xx_ohci->vbus_reg) {
> > +                     ret = regulator_disable(da8xx_ohci->vbus_reg);
> > +                     if (ret)
> > +                             dev_err(dev,
> > +                                     "Failed to disable regulator: %d\n",
> > +                                     ret);
> > +             }
> > +
>
> Unnecessary empty line here, that too one that introduces white space
> error. Please drop.
>
> Thanks,
> Sekhar