6.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Xu Yang xu.yang_2@nxp.com
commit 31a6afbe86e8e9deba9ab53876ec49eafc7fd901 upstream.
Shawn and John reported a hang issue during system suspend as below:
- USB gadget is enabled as Ethernet - There is data transfer over USB Ethernet (scp a big file between host and device) - Device is going in/out suspend (echo mem > /sys/power/state)
The root cause is the USB device controller is suspended but the USB bus is still active which caused the USB host continues to transfer data with device and the device continues to queue USB requests (in this case, a delayed TCP ACK packet trigger the issue) after controller is suspended, however the USB controller clock is already gated off. Then if udc driver access registers after that point, the system will hang.
The correct way to avoid such issue is to disconnect device from host when the USB bus is not at suspend state. Then the host will receive disconnect event and stop data transfer in time. To continue make USB gadget device work after system resume, this will reconnect device automatically.
To make usb wakeup work if USB bus is already at suspend state, this will keep connection for it only when USB device controller has enabled wakeup capability.
Reported-by: Shawn Guo shawnguo@kernel.org Reported-by: John Ernberg john.ernberg@actia.se Closes: https://lore.kernel.org/linux-usb/aEZxmlHmjeWcXiF3@dragon/ Tested-by: John Ernberg john.ernberg@actia.se # iMX8QXP Fixes: 235ffc17d014 ("usb: chipidea: udc: add suspend/resume support for device controller") Cc: stable stable@kernel.org Reviewed-by: Jun Li jun.li@nxp.com Signed-off-by: Xu Yang xu.yang_2@nxp.com Acked-by: Peter Chen peter.chen@kernel.org Link: https://lore.kernel.org/r/20250614124914.207540-1-xu.yang_2@nxp.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/chipidea/udc.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/drivers/usb/chipidea/udc.c +++ b/drivers/usb/chipidea/udc.c @@ -2374,6 +2374,10 @@ static void udc_suspend(struct ci_hdrc * */ if (hw_read(ci, OP_ENDPTLISTADDR, ~0) == 0) hw_write(ci, OP_ENDPTLISTADDR, ~0, ~0); + + if (ci->gadget.connected && + (!ci->suspended || !device_may_wakeup(ci->dev))) + usb_gadget_disconnect(&ci->gadget); }
static void udc_resume(struct ci_hdrc *ci, bool power_lost) @@ -2384,6 +2388,9 @@ static void udc_resume(struct ci_hdrc *c OTGSC_BSVIS | OTGSC_BSVIE); if (ci->vbus_active) usb_gadget_vbus_disconnect(&ci->gadget); + } else if (ci->vbus_active && ci->driver && + !ci->gadget.connected) { + usb_gadget_connect(&ci->gadget); }
/* Restore value 0 if it was set for power lost check */