[PATCH v10] usb: dwc3: fix gadget mode suspend interrupt handler issue

[Linyu Yuan <quic_linyyuan@quicinc.com>]

When work in gadget mode, currently driver doesn't update software level
link_state correctly as link state change event is not enabled for most
devices, in function dwc3_gadget_suspend_interrupt(), it will only pass
suspend event to UDC core when software level link state changes, so when
interrupt generated in sequences of suspend -> reset -> conndone ->
suspend, link state is not updated during reset and conndone, so second
suspend interrupt event will not pass to UDC core.

Remove link_state compare in dwc3_gadget_suspend_interrupt() and add a
suspended flag to replace the compare function.

Fixes: 799e9dc82968 ("usb: dwc3: gadget: conditionally disable Link State change events")
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
---

v10: (refer v9: https://lore.kernel.org/linux-usb/20230511054540.28239-1-quic_linyyuan@quicinc.com/)
1) update better changeset as Fixes tag 

v9: (refer v8 https://lore.kernel.org/linux-usb/20230510014718.13872-1-quic_linyyuan@quicinc.com/)
1) add a Fixes tag
2) add Acked-by tag from Thinh

v8: (refer v7 https://lore.kernel.org/linux-usb/20230509050743.5781-1-quic_linyyuan@quicinc.com/)
1) move some suspended flag clear to specific event handler

v7: (refer v6 https://lore.kernel.org/linux-usb/20230505014902.27313-1-quic_linyyuan@quicinc.com/)
1) reword suspended flag comment
2) remove one extra space in if operation
4) clear suspended flag for wakeup/reset/disconnect interrupt
3) clear suspended flag for remote wakeup related case.

v6: (refer v5 https://lore.kernel.org/linux-usb/1682476780-2367-1-git-send-email-quic_linyyuan@quicinc.com/)
1) change subject
2) only keep suspended flag related change

v5: (refer v4 https://lore.kernel.org/linux-usb/1682393256-15572-1-git-send-email-quic_linyyuan@quicinc.com/)
1) rename suspend_irq_happen to suspended and document it
2) add old_link_state for link change interrupt usage and change accordingly

v4: (refer v3 https://lore.kernel.org/linux-usb/1682053861-21737-1-git-send-email-quic_linyyuan@quicinc.com/)
1) remove link state checking in dwc3_gadget_wakeup_interrupt()
2) remove two switch/case to if opeartion

v3: (refer v2 https://lore.kernel.org/linux-usb/1682042472-21222-1-git-send-email-quic_linyyuan@quicinc.com/)
no code change since v2, changes compare v1 as below,
1) add a flag suspend_irq_happen to simplify dwc3_gadget_suspend_interrupt(),
   it will avoid refer to software level link_state, finally link_state will
   only used in dwc3_gadget_linksts_change_interrupt().
2) remove sw setting of link_state in dwc3_gadget_func_wakeup()
3) add dwc3_gadget_interrupt_early() to correct setting of link_state
   and suspend_irq_happen.

v2: update according v1 discussion
v1: https://lore.kernel.org/linux-usb/1675221286-23833-1-git-send-email-quic_linyyuan@quicinc.com/

 drivers/usb/dwc3/core.h   |  2 ++
 drivers/usb/dwc3/gadget.c | 12 +++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index d56457c02996..1f043c31a096 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1116,6 +1116,7 @@ struct dwc3_scratchpad_array {
  * @dis_metastability_quirk: set to disable metastability quirk.
  * @dis_split_quirk: set to disable split boundary.
  * @wakeup_configured: set if the device is configured for remote wakeup.
+ * @suspended: set to track suspend event due to U3/L2.
  * @imod_interval: set the interrupt moderation interval in 250ns
  *			increments or 0 to disable.
  * @max_cfg_eps: current max number of IN eps used across all USB configs.
@@ -1332,6 +1333,7 @@ struct dwc3 {
 	unsigned		dis_split_quirk:1;
 	unsigned		async_callbacks:1;
 	unsigned		wakeup_configured:1;
+	unsigned		suspended:1;
 
 	u16			imod_interval;
 
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index c0ca4d12f95d..f244bebf1ea0 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2440,6 +2440,7 @@ static int dwc3_gadget_func_wakeup(struct usb_gadget *g, int intf_id)
 			return -EINVAL;
 		}
 		dwc3_resume_gadget(dwc);
+		dwc->suspended = false;
 		dwc->link_state = DWC3_LINK_STATE_U0;
 	}
 
@@ -3938,6 +3939,8 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
 {
 	int			reg;
 
+	dwc->suspended = false;
+
 	dwc3_gadget_set_link_state(dwc, DWC3_LINK_STATE_RX_DET);
 
 	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
@@ -3962,6 +3965,8 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
 {
 	u32			reg;
 
+	dwc->suspended = false;
+
 	/*
 	 * Ideally, dwc3_reset_gadget() would trigger the function
 	 * drivers to stop any active transfers through ep disable.
@@ -4180,6 +4185,8 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
 
 static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc, unsigned int evtinfo)
 {
+	dwc->suspended = false;
+
 	/*
 	 * TODO take core out of low power mode when that's
 	 * implemented.
@@ -4277,6 +4284,7 @@ static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
 		if (dwc->gadget->wakeup_armed) {
 			dwc3_gadget_enable_linksts_evts(dwc, false);
 			dwc3_resume_gadget(dwc);
+			dwc->suspended = false;
 		}
 		break;
 	case DWC3_LINK_STATE_U1:
@@ -4303,8 +4311,10 @@ static void dwc3_gadget_suspend_interrupt(struct dwc3 *dwc,
 {
 	enum dwc3_link_state next = evtinfo & DWC3_LINK_STATE_MASK;
 
-	if (dwc->link_state != next && next == DWC3_LINK_STATE_U3)
+	if (!dwc->suspended && next == DWC3_LINK_STATE_U3) {
+		dwc->suspended = true;
 		dwc3_suspend_gadget(dwc);
+	}
 
 	dwc->link_state = next;
 }
-- 
2.17.1