releases/4.16.17/usb-musb-fix-remote-wakeup-racing-with-suspend.patch

From foo@baz Sun Jun 17 12:07:34 CEST 2018
From: "Daniel Glöckner" <dg@emlix.com>
Date: Mon, 14 May 2018 09:40:05 -0500
Subject: usb: musb: fix remote wakeup racing with suspend

From: "Daniel Glöckner" <dg@emlix.com>

[ Upstream commit ebc3dd688cd988754a304147753b13e58de1b5a1 ]

It has been observed that writing 0xF2 to the power register while it
reads as 0xF4 results in the register having the value 0xF0, i.e. clearing
RESUME and setting SUSPENDM in one go does not work. It might also violate
the USB spec to transition directly from resume to suspend, especially
when not taking T_DRSMDN into account. But this is what happens when a
remote wakeup occurs between SetPortFeature USB_PORT_FEAT_SUSPEND on the
root hub and musb_bus_suspend being called.

This commit returns -EBUSY when musb_bus_suspend is called while remote
wakeup is signalled and thus avoids to reset the RESUME bit. Ignoring
this error when musb_port_suspend is called from musb_hub_control is ok.

Signed-off-by: Daniel Glöckner <dg@emlix.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/musb/musb_host.c    |    5 ++++-
 drivers/usb/musb/musb_host.h    |    7 +++++--
 drivers/usb/musb/musb_virthub.c |   25 +++++++++++++++----------
 3 files changed, 24 insertions(+), 13 deletions(-)

--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -2530,8 +2530,11 @@ static int musb_bus_suspend(struct usb_h
 {
 	struct musb	*musb = hcd_to_musb(hcd);
 	u8		devctl;
+	int		ret;
 
-	musb_port_suspend(musb, true);
+	ret = musb_port_suspend(musb, true);
+	if (ret)
+		return ret;
 
 	if (!is_host_active(musb))
 		return 0;
--- a/drivers/usb/musb/musb_host.h
+++ b/drivers/usb/musb/musb_host.h
@@ -67,7 +67,7 @@ extern void musb_host_rx(struct musb *,
 extern void musb_root_disconnect(struct musb *musb);
 extern void musb_host_resume_root_hub(struct musb *musb);
 extern void musb_host_poke_root_hub(struct musb *musb);
-extern void musb_port_suspend(struct musb *musb, bool do_suspend);
+extern int musb_port_suspend(struct musb *musb, bool do_suspend);
 extern void musb_port_reset(struct musb *musb, bool do_reset);
 extern void musb_host_finish_resume(struct work_struct *work);
 #else
@@ -99,7 +99,10 @@ static inline void musb_root_disconnect(
 static inline void musb_host_resume_root_hub(struct musb *musb)	{}
 static inline void musb_host_poll_rh_status(struct musb *musb)	{}
 static inline void musb_host_poke_root_hub(struct musb *musb)	{}
-static inline void musb_port_suspend(struct musb *musb, bool do_suspend) {}
+static inline int musb_port_suspend(struct musb *musb, bool do_suspend)
+{
+	return 0;
+}
 static inline void musb_port_reset(struct musb *musb, bool do_reset) {}
 static inline void musb_host_finish_resume(struct work_struct *work) {}
 #endif
--- a/drivers/usb/musb/musb_virthub.c
+++ b/drivers/usb/musb/musb_virthub.c
@@ -48,14 +48,14 @@ void musb_host_finish_resume(struct work
 	spin_unlock_irqrestore(&musb->lock, flags);
 }
 
-void musb_port_suspend(struct musb *musb, bool do_suspend)
+int musb_port_suspend(struct musb *musb, bool do_suspend)
 {
 	struct usb_otg	*otg = musb->xceiv->otg;
 	u8		power;
 	void __iomem	*mbase = musb->mregs;
 
 	if (!is_host_active(musb))
-		return;
+		return 0;
 
 	/* NOTE:  this doesn't necessarily put PHY into low power mode,
 	 * turning off its clock; that's a function of PHY integration and
@@ -66,16 +66,20 @@ void musb_port_suspend(struct musb *musb
 	if (do_suspend) {
 		int retries = 10000;
 
-		power &= ~MUSB_POWER_RESUME;
-		power |= MUSB_POWER_SUSPENDM;
-		musb_writeb(mbase, MUSB_POWER, power);
+		if (power & MUSB_POWER_RESUME)
+			return -EBUSY;
+
+		if (!(power & MUSB_POWER_SUSPENDM)) {
+			power |= MUSB_POWER_SUSPENDM;
+			musb_writeb(mbase, MUSB_POWER, power);
 
-		/* Needed for OPT A tests */
-		power = musb_readb(mbase, MUSB_POWER);
-		while (power & MUSB_POWER_SUSPENDM) {
+			/* Needed for OPT A tests */
 			power = musb_readb(mbase, MUSB_POWER);
-			if (retries-- < 1)
-				break;
+			while (power & MUSB_POWER_SUSPENDM) {
+				power = musb_readb(mbase, MUSB_POWER);
+				if (retries-- < 1)
+					break;
+			}
 		}
 
 		musb_dbg(musb, "Root port suspended, power %02x", power);
@@ -111,6 +115,7 @@ void musb_port_suspend(struct musb *musb
 		schedule_delayed_work(&musb->finish_resume_work,
 				      msecs_to_jiffies(USB_RESUME_TIMEOUT));
 	}
+	return 0;
 }
 
 void musb_port_reset(struct musb *musb, bool do_reset)