The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From b65ba0c362be665192381cc59e3ac3ef6f0dd1e1 Mon Sep 17 00:00:00 2001
From: Thomas Petazzoni thomas.petazzoni@bootlin.com Date: Fri, 28 May 2021 16:04:46 +0200 Subject: [PATCH] usb: musb: fix MUSB_QUIRK_B_DISCONNECT_99 handling
In commit 92af4fc6ec33 ("usb: musb: Fix suspend with devices connected for a64"), the logic to support the MUSB_QUIRK_B_DISCONNECT_99 quirk was modified to only conditionally schedule the musb->irq_work delayed work.
This commit badly breaks ECM Gadget on AM335X. Indeed, with this commit, one can observe massive packet loss:
$ ping 192.168.0.100 ... 15 packets transmitted, 3 received, 80% packet loss, time 14316ms
Reverting this commit brings back a properly functioning ECM Gadget. An analysis of the commit seems to indicate that a mistake was made: the previous code was not falling through into the MUSB_QUIRK_B_INVALID_VBUS_91, but now it is, unless the condition is taken.
Changing the logic to be as it was before the problematic commit *and* only conditionally scheduling musb->irq_work resolves the regression:
$ ping 192.168.0.100 ... 64 packets transmitted, 64 received, 0% packet loss, time 64475ms
Fixes: 92af4fc6ec33 ("usb: musb: Fix suspend with devices connected for a64") Cc: stable@vger.kernel.org Tested-by: Alexandre Belloni alexandre.belloni@bootlin.com Tested-by: Drew Fustini drew@beagleboard.org Acked-by: Tony Lindgren tony@atomide.com Signed-off-by: Thomas Petazzoni thomas.petazzoni@bootlin.com Link: https://lore.kernel.org/r/20210528140446.278076-1-thomas.petazzoni@bootlin.c... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c index 8f09a387b773..4c8f0112481f 100644 --- a/drivers/usb/musb/musb_core.c +++ b/drivers/usb/musb/musb_core.c @@ -2009,9 +2009,8 @@ static void musb_pm_runtime_check_session(struct musb *musb) schedule_delayed_work(&musb->irq_work, msecs_to_jiffies(1000)); musb->quirk_retries--; - break; } - fallthrough; + break; case MUSB_QUIRK_B_INVALID_VBUS_91: if (musb->quirk_retries && !musb->flush_irq_work) { musb_dbg(musb,