diff options
| author | Prashanth K <quic_prashk@quicinc.com> | 2024-08-28 12:13:02 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-09-03 10:03:06 +0200 |
| commit | 00dcf2fa449f23a263343d7fe051741bdde65d0b (patch) | |
| tree | 45069781f210e60743663afb43e4e1d6d0b4f1b2 /drivers | |
| parent | 431c1646e1f86b949fa3685efc50b660a364c2b6 (diff) | |
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: 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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/usb/dwc3/gadget.c | 41 |
1 files changed, 17 insertions, 24 deletions
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 89fc690fdf34..291bc549935b 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -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 * @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_ep *dep, unsigned int cmd, 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 |