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From:   Bartosz Golaszewski <brgl@bgdev.pl>
Date:   Wed, 3 Apr 2019 17:36:07 +0200
Message-ID: <CAMRc=MdNxZ0L+j7VBz32y-nJgJmgN73-o0YWQct8DkWoyttFGg@mail.gmail.com>
Subject: Re: [PATCH v2 3/6] usb: ohci-da8xx: disable the regulator if the
 overcurrent irq fired
To:     Sekhar Nori <nsekhar@ti.com>, Kevin Hilman <khilman@kernel.org>,
        Alan Stern <stern@rowland.harvard.edu>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-usb@vger.kernel.org,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>
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pt., 29 mar 2019 o 10:33 Bartosz Golaszewski <brgl@bgdev.pl> napisa=C5=82(a=
):
>
> From: Bartosz Golaszewski <bgolaszewski@baylibre.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@baylibre.com>
> ---
>  drivers/usb/host/ohci-da8xx.c | 29 ++++++++++++++++++++++++-----
>  1 file changed, 24 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/host/ohci-da8xx.c b/drivers/usb/host/ohci-da8xx.=
c
> index 9c6d1f03b871..35eb2cb96a8f 100644
> --- a/drivers/usb/host/ohci-da8xx.c
> +++ b/drivers/usb/host/ohci-da8xx.c
> @@ -206,8 +206,25 @@ static irqreturn_t ohci_da8xx_oc_handler(int irq, vo=
id *data)
>  {
>         struct da8xx_ohci_hcd *da8xx_ohci =3D data;
>
> -       if (gpiod_get_value(da8xx_ohci->oc_gpio))
> -               gpiod_set_value(da8xx_ohci->vbus_gpio, 0);
> +       if (gpiod_get_value(da8xx_ohci->oc_gpio)) {
> +               if (da8xx_ohci->vbus_gpio)
> +                       gpiod_set_value(da8xx_ohci->vbus_gpio, 0);
> +               else if (da8xx_ohci->vbus_reg)
> +                       return IRQ_WAKE_THREAD;
> +       }
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t ohci_da8xx_oc_thread(int irq, void *data)
> +{
> +       struct da8xx_ohci_hcd *da8xx_ohci =3D data;
> +       struct device *dev =3D da8xx_ohci->hcd->self.controller;
> +       int ret;
> +
> +       ret =3D regulator_disable(da8xx_ohci->vbus_reg);
> +       if (ret)
> +               dev_err(dev, "Failed to disable regulator: %d\n", ret);
>
>         return IRQ_HANDLED;
>  }
> @@ -434,9 +451,11 @@ static int ohci_da8xx_probe(struct platform_device *=
pdev)
>                 if (oc_irq < 0)
>                         goto err;
>
> -               error =3D devm_request_irq(dev, oc_irq, ohci_da8xx_oc_han=
dler,
> -                               IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLIN=
G,
> -                               "OHCI over-current indicator", da8xx_ohci=
);
> +               error =3D devm_request_threaded_irq(dev, oc_irq,
> +                               ohci_da8xx_oc_handler, ohci_da8xx_oc_thre=
ad,
> +                               IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLIN=
G |
> +                               IRQF_ONESHOT, "OHCI over-current indicato=
r",
> +                               da8xx_ohci);

Ugh I noticed a problem with this patch if the module is built-in -
after calling devm_request_threaded_irq() any subsequent msleep() will
hang. This doesn't happen if the driver is built as a module. I'm not
sure what the reason is yet.

Bart

>                 if (error)
>                         goto err;
>         }
> --
> 2.21.0
>