Re: [PATCH] usb: musb: fix idling for suspend after disconnect interrupt

[Tony Lindgren <tony@atomide.com>]

Hi,

* Bhushan Shah <bshah@kde.org> [201027 04:55]:
> Hi Tony,
> 
> On Mon, Nov 25, 2019 at 07:41:51PM -0800, Tony Lindgren wrote:
> > When disconnected as USB B-device, we sometimes get a suspend interrupt
> > after disconnect interrupt. In that case we have devctl set to 99 with
> > VBUS still valid and musb_pm_runtime_check_session() wrongly things we
> > have an active session. We have no other interrupts after disconnect
> > coming in this case at least with the omap2430 glue.
> 
> So I had been debugging a issue with musb_hrdc driver preventing a
> suspend on the pinephone, which is Allwinner A64 platform.

Great. After that you might want to take a look and make sure that musb
also gets idled properly during runtime with no devices connected :)

> Namely, if I have USB connected, and I try to suspend, it would hang
> until USB is disconnected. After enabling tracing, I realized that is
> hanging after this commit. Reverting it makes device suspend and resume
> correctly.
> 
> Some more of debugging notes can be found at,
> 
> https://gitlab.com/postmarketOS/pmaports/-/issues/839
> 
> I wonder what would be right solution here? Disable this quirk somehow
> for device?

Hmm maybe we're just missing the check for suspend here. Maybe
give the following untested patch a try?

I'll give it a try here too but it might be few days.

Seems like we might be able to eventually simplify the suspend and
quirk check stuff, but let's fix the $subject issue first.

Regards,

Tony

8< ----------------------
diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -2005,10 +2005,14 @@ static void musb_pm_runtime_check_session(struct musb *musb)
 		MUSB_DEVCTL_HR;
 	switch (devctl & ~s) {
 	case MUSB_QUIRK_B_DISCONNECT_99:
-		musb_dbg(musb, "Poll devctl in case of suspend after disconnect\n");
-		schedule_delayed_work(&musb->irq_work,
-				      msecs_to_jiffies(1000));
-		break;
+		if (musb->quirk_retries && !musb->flush_irq_work) {
+			musb_dbg(musb, "Poll devctl in case of suspend after disconnect\n");
+			schedule_delayed_work(&musb->irq_work,
+					      msecs_to_jiffies(1000));
+			musb->quirk_retries--;
+			break;
+		}
+		/* fall through */
 	case MUSB_QUIRK_B_INVALID_VBUS_91:
 		if (musb->quirk_retries && !musb->flush_irq_work) {
 			musb_dbg(musb,