usb: dwc3: gadget: Disable GUSB2PHYCFG.SUSPHY for End Transfer

Upstream Linux commit 3aa07f72894d.

If there's a disconnection while operating in eSS, there may be a delay
in VBUS drop response from the connector. In that case, the internal
link state may drop to operate in usb2 speed while the controller thinks
the VBUS is still high. The driver must make sure to disable
GUSB2PHYCFG.SUSPHY when sending endpoint command while in usb2 speed.
The End Transfer command may be called, and only that command needs to
go through at this point. Let's keep it simple and unconditionally
disable GUSB2PHYCFG.SUSPHY whenever we issue the command.

This scenario is not seen in real hardware. In a rare case, our
prototype type-c controller/interface may have a slow response
triggerring this issue.

Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/5651117207803c26e2f22ddf4e5ce9e865dcf7c7.1668045468.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Link: https://lore.kernel.org/r/20240412202611.3565052-7-alexander.sverdlin@siemens.com
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index e8e8f82c05ed3126d1754cbfbccdbea0fd875191..fab32575647df72e993d4e79732fdc926d341b72 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -315,7 +315,8 @@ int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
         *
         * DWC_usb3 3.30a and DWC_usb31 1.90a programming guide section 3.2.2
         */
-       if (dwc->gadget.speed <= USB_SPEED_HIGH) {
+       if (dwc->gadget.speed <= USB_SPEED_HIGH ||
+           DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_ENDTRANSFER) {
                reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
                if (unlikely(reg & DWC3_GUSB2PHYCFG_SUSPHY)) {
                        saved_config |= DWC3_GUSB2PHYCFG_SUSPHY;