Patch "usb: musb: Fix host mode error -71 regression" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

usb: musb: Fix host mode error -71 regression

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-musb-fix-host-mode-error-71-regression.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Tony Lindgren <[email protected]>
Date: Tue, 24 Jan 2017 09:18:57 -0600
Subject: usb: musb: Fix host mode error -71 regression

From: Tony Lindgren <[email protected]>

commit 407788b51db6f6aab499d02420082f436abf3238 upstream.

Commit 467d5c980709 ("usb: musb: Implement session bit based runtime PM for musb-core") started implementing musb generic runtime PM support by introducing devctl register session bit based state control.

This caused a regression where if a USB mass storage device is connected to a USB hub, we can get:

usb 1-1: reset high-speed USB device number 2 using musb-hdrc usb 1-1: device descriptor read/64, error -71
usb 1-1.1: new high-speed USB device number 4 using musb-hdrc

This is because before the USB storage device is connected, musb is in OTG_STATE_A_SUSPEND. And we currently only set need_finish_resume in musb_stage0_irq() and the related code calling finish_resume_work in musb_resume() and musb_runtime_resume() never gets called.

To fix the issue, we can call schedule_delayed_work() directly in musb_stage0_irq() to have finish_resume_work run.

And we should no longer never get interrupts when when suspended. We have changed musb to no longer need pm_runtime_irqsafe(). The need_finish_resume flag was added in commit 9298b4aad37e ("usb:
musb: fix device hotplug behind hub") and no longer applies as far as I can tell. So let's just remove the earlier code that no longer is needed.

---
 drivers/usb/musb/musb_core.c |   15 ++-------------
 drivers/usb/musb/musb_core.h |    1 -
 2 files changed, 2 insertions(+), 14 deletions(-)

@@ -578,11 +578,11 @@ static irqreturn_t musb_stage0_irq(struc
 						| MUSB_PORT_STAT_RESUME;
 				musb->rh_timer = jiffies
 					+ msecs_to_jiffies(USB_RESUME_TIMEOUT);
-				musb->need_finish_resume = 1;
-
 				musb->xceiv->otg->state = OTG_STATE_A_HOST;
 				musb->is_active = 1;
 				musb_host_resume_root_hub(musb);
+				schedule_delayed_work(&musb->finish_resume_work,
+					msecs_to_jiffies(USB_RESUME_TIMEOUT));
 				break;
 			case OTG_STATE_B_WAIT_ACON:
 				musb->xceiv->otg->state = OTG_STATE_B_PERIPHERAL;

@@ -2691,11 +2691,6 @@ static int musb_resume(struct device *de
 	mask = MUSB_DEVCTL_BDEVICE | MUSB_DEVCTL_FSDEV | MUSB_DEVCTL_LSDEV;
 	if ((devctl & mask) != (musb->context.devctl & mask))
 		musb->port1_status = 0;
-	if (musb->need_finish_resume) {
-		musb->need_finish_resume = 0;
-		schedule_delayed_work(&musb->finish_resume_work,
-				      msecs_to_jiffies(USB_RESUME_TIMEOUT));
-	}
 
 	/*
 	 * The USB HUB code expects the device to be in RPM_ACTIVE once it came

@@ -2747,12 +2742,6 @@ static int musb_runtime_resume(struct de
 
 	musb_restore_context(musb);
 
-	if (musb->need_finish_resume) {
-		musb->need_finish_resume = 0;
-		schedule_delayed_work(&musb->finish_resume_work,
-				msecs_to_jiffies(USB_RESUME_TIMEOUT));
-	}
-
 	spin_lock_irqsave(&musb->lock, flags);
 	error = musb_run_resume_work(musb);
 	if (error)

@@ -410,7 +410,6 @@ struct musb {
 
 	/* is_suspended means USB B_PERIPHERAL suspend */
 	unsigned		is_suspended:1;
-	unsigned		need_finish_resume :1;
 
 	/* may_wakeup means remote wakeup is enabled */
 	unsigned		may_wakeup:1;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/dmaengine-cppi41-fix-runtime-pm-timeouts-with-usb-mass-storage.patch queue-4.9/dmaengine-cppi41-fix-oops-in-cppi41_runtime_resume.patch queue-4.9/usb-musb-fix-host-mode-error-71-regression.patch