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

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Message-ID: <fbe20a5f-0f64-cadf-2c1e-88a468d54a07@redhat.com>
Date:   Fri, 9 Aug 2019 13:06:01 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Yauhen Kharuzhy <jekhor@...il.com>, linux-kernel@...r.kernel.org,
        Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH] extcon-intel-cht-wc: Don't reset USB data connection at
 probe

Hi,

On 8/9/19 12:01 AM, Yauhen Kharuzhy 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.
> 
> 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..3ae573e93e6e 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_FLOAT)
> +		cht_wc_extcon_set_phymux(ext, MUX_SEL_PMIC);

The check here should be != INTEL_USB_ID_GND, when we are connected as
device we are charging from the host we are connected to and the port
we are connected to may be a CDP (charging downstream port) instead of
a SDP (standard downstream port) allowing us to charge at 1.5A instead
of 0.5A, also != INTEL_USB_ID_GND matches the condition used in
cht_wc_extcon_pwrsrc_event to determine if we should continue with
charger detection there.

Like your other patch I will try to give this one a  test-run tomorrow.

Regards,

Hans


>   
>   	/* Get initial state */
>   	cht_wc_extcon_pwrsrc_event(ext);
>