linux-kernel - Re: [PATCH v2] extcon-intel-cht-wc: Don't reset USB data connection at probe

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Message-ID: <CAHp75VeCFYZ11c0jW3aXZTXHROfU5k0YRcJC4Vz3S2_tvDwt4w@mail.gmail.com>
Date:   Fri, 20 Sep 2019 11:25:45 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Yauhen Kharuzhy <jekhor@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v2] extcon-intel-cht-wc: Don't reset USB data connection
 at probe

On Tue, Sep 17, 2019 at 10:29 AM Yauhen Kharuzhy <jekhor@...il.com> wrote:
>
> Intel Cherry Trail Whiskey Cove extcon driver connect USB data lines to
> PMIC at driver probing for further charger detection. This causes reset of
> USB data sessions and removing all devices from bus. If system was
> booted from Live CD or USB dongle, this makes system unusable.
>
> Check if USB ID pin is floating and re-route data lines in this case
> only, don't touch otherwise.
>

FWIW,
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Signed-off-by: Yauhen Kharuzhy <jekhor@...il.com>
> ---
>  drivers/extcon/extcon-intel-cht-wc.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/extcon/extcon-intel-cht-wc.c b/drivers/extcon/extcon-intel-cht-wc.c
> index 9d32150e68db..da1886a92f75 100644
> --- a/drivers/extcon/extcon-intel-cht-wc.c
> +++ b/drivers/extcon/extcon-intel-cht-wc.c
> @@ -338,6 +338,7 @@ static int cht_wc_extcon_probe(struct platform_device *pdev)
>         struct intel_soc_pmic *pmic = dev_get_drvdata(pdev->dev.parent);
>         struct cht_wc_extcon_data *ext;
>         unsigned long mask = ~(CHT_WC_PWRSRC_VBUS | CHT_WC_PWRSRC_USBID_MASK);
> +       int pwrsrc_sts, id;
>         int irq, ret;
>
>         irq = platform_get_irq(pdev, 0);
> @@ -387,8 +388,19 @@ static int cht_wc_extcon_probe(struct platform_device *pdev)
>                 goto disable_sw_control;
>         }
>
> -       /* Route D+ and D- to PMIC for initial charger detection */
> -       cht_wc_extcon_set_phymux(ext, MUX_SEL_PMIC);
> +       ret = regmap_read(ext->regmap, CHT_WC_PWRSRC_STS, &pwrsrc_sts);
> +       if (ret) {
> +               dev_err(ext->dev, "Error reading pwrsrc status: %d\n", ret);
> +               goto disable_sw_control;
> +       }
> +
> +       id = cht_wc_extcon_get_id(ext, pwrsrc_sts);
> +
> +       /* If no USB host or device connected, route D+ and D- to PMIC for
> +        * initial charger detection
> +        */
> +       if (id != INTEL_USB_ID_GND)
> +               cht_wc_extcon_set_phymux(ext, MUX_SEL_PMIC);
>
>         /* Get initial state */
>         cht_wc_extcon_pwrsrc_event(ext);
> --
> 2.23.0.rc1
>


-- 
With Best Regards,
Andy Shevchenko