FAILED: Patch "usb: dwc2: fix resume failure if dr_mode is host" failed to apply to 5.15-stable tree

FAILED: Patch "usb: dwc2: fix resume failure if dr_mode is host" failed to apply to 5.15-stable tree

[Sasha Levin]

The patch below does not apply to the 5.15-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,
Sasha

------------------ original commit in Linus's tree ------------------

From a52e4f2dff413b58c7200e89bb6540bd995e1269 Mon Sep 17 00:00:00 2001
From: Jisheng Zhang <jszhang@kernel.org>
Date: Thu, 29 Jan 2026 10:15:34 +0800
Subject: [PATCH] usb: dwc2: fix resume failure if dr_mode is host

commit 13b1f8e25bfd1 ("usb: dwc2: Force mode optimizations") removed the
dwc2_force_mode(hsotg, true) in dwc2_force_dr_mode() if dr_mode is host.

But this brings a bug: the controller fails to resume back as host,
further debugging shows that the controller is resumed as peripheral.
The reason is dwc2_force_dr_mode() missed the host mode forcing, and
when resuming from s2ram, GINTSTS is 0 by default, dwc2_is_device_mode
in dwc2_resume() misreads this as the controller is in peripheral mode.

Fix the resume failure by adding back the dwc2_force_mode(hsotg, true).

Then an obvious question is: why this bug hasn't been observed and fixed
for about six years? There are two resons: most dwc2 platforms set the
dr_mode as otg; Some platforms don't have suspend & resume support yet.

Fixes: 13b1f8e25bfd1 ("usb: dwc2: Force mode optimizations")
Cc: stable <stable@kernel.org>
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://patch.msgid.link/20260129021534.10411-1-jszhang@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/dwc2/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
index c3d24312db0fe..f375c5185bfe2 100644
--- a/drivers/usb/dwc2/core.c
+++ b/drivers/usb/dwc2/core.c
@@ -578,6 +578,7 @@ void dwc2_force_dr_mode(struct dwc2_hsotg *hsotg)
 {
 	switch (hsotg->dr_mode) {
 	case USB_DR_MODE_HOST:
+		dwc2_force_mode(hsotg, true);
 		/*
 		 * NOTE: This is required for some rockchip soc based
 		 * platforms on their host-only dwc2.
-- 
2.51.0