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UPSTREAM: usb: dwc3: Avoid waking up gadget during startxfer

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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>

Bug: 365464688
(cherry picked from commit 00dcf2fa44)
Change-Id: If6b97cdd5c9326052ec3730e8183986606806687
Signed-off-by: Prashanth K <quic_prashk@quicinc.com>
This commit is contained in:
Prashanth K 2024-08-28 12:13:02 +05:30 committed by Treehugger Robot
parent cd188cc0b5
commit a338a543b3
1 changed files with 17 additions and 24 deletions
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41
drivers/usb/dwc3/gadget.c
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@ -287,6 +287,23 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc, bool async);
* *
* Caller should handle locking. This function will issue @cmd with given * Caller should handle locking. This function will issue @cmd with given
* @params to @dep and wait for its completion. * @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, int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
struct dwc3_gadget_ep_cmd_params *params) struct dwc3_gadget_ep_cmd_params *params)
@ -327,30 +344,6 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg); 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 * For some commands such as Update Transfer command, DEPCMDPARn
* registers are reserved. Since the driver often sends Update Transfer * registers are reserved. Since the driver often sends Update Transfer