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

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Date:   Tue, 17 Sep 2019 00:15:36 +0300
From:   Yauhen Kharuzhy <jekhor@...il.com>
To:     linux-kernel@...r.kernel.org, Chanwoo Choi <cw00.choi@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Yauhen Kharuzhy <jekhor@...il.com>
Subject: [PATCH v2] extcon-intel-cht-wc: Don't reset USB data connection at probe

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..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