Hi all,

please include b65ba0c362be665192381cc59e3ac3ef6f0dd1e1 also on the stable-trees up to v5.10 (i think v5.13 was the first fixed tree).

Serial gadget on AM335X is also affected, breaks with NULL pointer references and needs this patch. Here is the patch for the v4.19 tree, cherry picked and manually applied from original commit b65ba0c362be665192381cc59e3ac3ef6f0dd1e1:

From 483d904168b08cf1497c73516c432bde9ae94055 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 --- drivers/usb/musb/musb_core.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c index 2a874058dff1..4d2de9ce03f9 100644 --- a/drivers/usb/musb/musb_core.c +++ b/drivers/usb/musb/musb_core.c @@ -1873,9 +1873,8 @@ static void musb_pm_runtime_check_session(struct musb *musb) schedule_delayed_work(&musb->irq_work, msecs_to_jiffies(1000)); musb->quirk_retries--; - break; } - /* fall through */ + break; case MUSB_QUIRK_B_INVALID_VBUS_91: if (musb->quirk_retries && !musb->flush_irq_work) { musb_dbg(musb,