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usb: dwc3: Avoid waking up gadget during startxfer
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: c36d8e947a
("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>
This commit is contained in:
parent
431c1646e1
commit
00dcf2fa44
1 changed files with 17 additions and 24 deletions
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@ -287,6 +287,23 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc, bool async);
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*
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* Caller should handle locking. This function will issue @cmd with given
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* @params to @dep and wait for its completion.
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*
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* According to the programming guide, if the link state is in L1/L2/U3,
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* then sending the Start Transfer command may not complete. The
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* programming guide suggested to bring the link state back to ON/U0 by
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* performing remote wakeup prior to sending the command. However, don't
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* initiate remote wakeup when the user/function does not send wakeup
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* request via wakeup ops. Send the command when it's allowed.
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*
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* Notes:
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* For L1 link state, issuing a command requires the clearing of
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* GUSB2PHYCFG.SUSPENDUSB2, which turns on the signal required to complete
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* the given command (usually within 50us). This should happen within the
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* command timeout set by driver. No additional step is needed.
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*
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* For L2 or U3 link state, the gadget is in USB suspend. Care should be
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* taken when sending Start Transfer command to ensure that it's done after
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* USB resume.
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*/
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int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
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struct dwc3_gadget_ep_cmd_params *params)
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@ -327,30 +344,6 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
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dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
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}
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if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_STARTTRANSFER) {
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int link_state;
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/*
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* Initiate remote wakeup if the link state is in U3 when
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* operating in SS/SSP or L1/L2 when operating in HS/FS. If the
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* link state is in U1/U2, no remote wakeup is needed. The Start
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* Transfer command will initiate the link recovery.
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*/
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link_state = dwc3_gadget_get_link_state(dwc);
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switch (link_state) {
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case DWC3_LINK_STATE_U2:
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if (dwc->gadget->speed >= USB_SPEED_SUPER)
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break;
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fallthrough;
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case DWC3_LINK_STATE_U3:
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ret = __dwc3_gadget_wakeup(dwc, false);
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dev_WARN_ONCE(dwc->dev, ret, "wakeup failed --> %d\n",
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ret);
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break;
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}
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}
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/*
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* For some commands such as Update Transfer command, DEPCMDPARn
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* registers are reserved. Since the driver often sends Update Transfer
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