linux-kernel - [PATCH 17/20] phy_sun4i_usb: set_mode: Allow using set

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Date:   Fri, 18 Nov 2016 18:58:40 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     <gregkh@...uxfoundation.org>
CC:     <kishon@...com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 17/20] phy_sun4i_usb: set_mode: Allow using set_mode to force end the current session

From: Hans de Goede <hdegoede@...hat.com>

The sunxi musb has a bug where sometimes it will generate a babble
error on device disconnect instead of a disconnect irq. When this
happens the musb-controller switches from host mode to device mode
(it clears MUSB_DEVCTL_SESSION and sets MUSB_DEVCTL_BDEVICE) and
gets stuck in this state.

Clearing this requires reporting Vbus low for 200 or more ms, but
on some devices Vbus is simply always high (host-only mode, no Vbus
control).

This commit modifies sun4i_usb_phy_set_mode so that it will force
end the current session when called with the current mode, before this
commit calling set_mode with the current mode was a nop since id_det
would stay the same resulting in the detect_work not doing anything.

This allows the sunxi-musb glue to use sun4i_usb_phy_set_mode to force
end the current session without changing the mode, to fixup the stuck
state after a babble error.

Signed-off-by: Hans de Goede <hdegoede@...hat.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
---
 drivers/phy/phy-sun4i-usb.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/phy/phy-sun4i-usb.c b/drivers/phy/phy-sun4i-usb.c
index fec34f5..bf28a0f 100644
--- a/drivers/phy/phy-sun4i-usb.c
+++ b/drivers/phy/phy-sun4i-usb.c
@@ -436,25 +436,31 @@ static int sun4i_usb_phy_set_mode(struct phy *_phy, enum phy_mode mode)
 {
 	struct sun4i_usb_phy *phy = phy_get_drvdata(_phy);
 	struct sun4i_usb_phy_data *data = to_sun4i_usb_phy_data(phy);
+	int new_mode;

 	if (phy->index != 0)
 		return -EINVAL;

 	switch (mode) {
 	case PHY_MODE_USB_HOST:
-		data->dr_mode = USB_DR_MODE_HOST;
+		new_mode = USB_DR_MODE_HOST;
 		break;
 	case PHY_MODE_USB_DEVICE:
-		data->dr_mode = USB_DR_MODE_PERIPHERAL;
+		new_mode = USB_DR_MODE_PERIPHERAL;
 		break;
 	case PHY_MODE_USB_OTG:
-		data->dr_mode = USB_DR_MODE_OTG;
+		new_mode = USB_DR_MODE_OTG;
 		break;
 	default:
 		return -EINVAL;
 	}

-	dev_info(&_phy->dev, "Changing dr_mode to %d\n", (int)data->dr_mode);
+	if (new_mode != data->dr_mode) {
+		dev_info(&_phy->dev, "Changing dr_mode to %d\n", new_mode);
+		data->dr_mode = new_mode;
+	}
+
+	data->id_det = -1; /* Force reprocessing of id */
 	data->force_session_end = true;
 	queue_delayed_work(system_wq, &data->detect, 0);

-- 
1.7.9.5