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

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Date:   Tue, 17 Sep 2019 14:13:22 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Yauhen Kharuzhy <jekhor@...il.com>
Cc:     linux-kernel@...r.kernel.org, Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH v2] extcon-intel-cht-wc: Don't reset USB data connection
 at probe

On Tue, Sep 17, 2019 at 12:15:36AM +0300, 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.

> +	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);

We have second implementation of this. Would it make sense to split to some
helper?

> +	/* If no USB host or device connected, route D+ and D- to PMIC for
> +	 * initial charger detection
> +	 */

I'm not sure it's acceptable style of multi-line comment, but it's up to
maintainer.

> +	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