6.6-stable review patch. If anyone has any objections, please let me know.
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From: Prashanth K quic_prashk@quicinc.com
commit 00dcf2fa449f23a263343d7fe051741bdde65d0b upstream.
When operating in High-Speed, it is observed that DSTS[USBLNKST] doesn't update link state immediately after receiving the wakeup interrupt. Since wakeup event handler calls the resume callbacks, there is a chance that function drivers can perform an ep queue, which in turn tries to perform remote wakeup from send_gadget_ep_cmd(STARTXFER). This happens because DSTS[[21:18] wasn't updated to U0 yet, it's observed that the latency of DSTS can be in order of milli-seconds. Hence avoid calling gadget_wakeup during startxfer to prevent unnecessarily issuing remote wakeup to host.
Fixes: c36d8e947a56 ("usb: dwc3: gadget: put link to U0 before Start Transfer") Cc: stable@vger.kernel.org Suggested-by: Thinh Nguyen Thinh.Nguyen@synopsys.com Signed-off-by: Prashanth K quic_prashk@quicinc.com Acked-by: Thinh Nguyen Thinh.Nguyen@synopsys.com Link: https://lore.kernel.org/r/20240828064302.3796315-1-quic_prashk@quicinc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/dwc3/gadget.c | 41 +++++++++++++++++------------------------ 1 file changed, 17 insertions(+), 24 deletions(-)
--- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -287,6 +287,23 @@ static int __dwc3_gadget_wakeup(struct d * * Caller should handle locking. This function will issue @cmd with given * @params to @dep and wait for its completion. + * + * According to the programming guide, if the link state is in L1/L2/U3, + * then sending the Start Transfer command may not complete. The + * programming guide suggested to bring the link state back to ON/U0 by + * performing remote wakeup prior to sending the command. However, don't + * initiate remote wakeup when the user/function does not send wakeup + * request via wakeup ops. Send the command when it's allowed. + * + * Notes: + * For L1 link state, issuing a command requires the clearing of + * GUSB2PHYCFG.SUSPENDUSB2, which turns on the signal required to complete + * the given command (usually within 50us). This should happen within the + * command timeout set by driver. No additional step is needed. + * + * For L2 or U3 link state, the gadget is in USB suspend. Care should be + * taken when sending Start Transfer command to ensure that it's done after + * USB resume. */ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd, struct dwc3_gadget_ep_cmd_params *params) @@ -327,30 +344,6 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg); }
- if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_STARTTRANSFER) { - int link_state; - - /* - * Initiate remote wakeup if the link state is in U3 when - * operating in SS/SSP or L1/L2 when operating in HS/FS. If the - * link state is in U1/U2, no remote wakeup is needed. The Start - * Transfer command will initiate the link recovery. - */ - link_state = dwc3_gadget_get_link_state(dwc); - switch (link_state) { - case DWC3_LINK_STATE_U2: - if (dwc->gadget->speed >= USB_SPEED_SUPER) - break; - - fallthrough; - case DWC3_LINK_STATE_U3: - ret = __dwc3_gadget_wakeup(dwc, false); - dev_WARN_ONCE(dwc->dev, ret, "wakeup failed --> %d\n", - ret); - break; - } - } - /* * For some commands such as Update Transfer command, DEPCMDPARn * registers are reserved. Since the driver often sends Update Transfer