[RFC PATCH v2 2/3] usb: dwc3: gadget: Wait for ep0 xfers to complete during dequeue

Wesley Cheng
2022-02-16T00:09:02Z

If the request being dequeued is currently active, then the current
logic is to issue a stop transfer command, and allow the command
completion to cleanup the cancelled list. The DWC3 controller will
run into endxfer command timeouts if there is an ongoing EP0
transaction. If this is the case, wait for the EP0 completion event
before proceeding to retry the endxfer command again.

Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
drivers/usb/dwc3/core.h | 5 +++++
drivers/usb/dwc3/ep0.c | 2 ++
drivers/usb/dwc3/gadget.c | 47 +++++++++++++++++++++++++++++++++------
3 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index a411682e7f44..00348d6d479b 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -736,6 +736,7 @@ struct dwc3_ep {
#define DWC3_EP_FIRST_STREAM_PRIMED BIT(10)
#define DWC3_EP_PENDING_CLEAR_STALL BIT(11)
#define DWC3_EP_TXFIFO_RESIZED BIT(12)
+#define DWC3_EP_PENDING_DEQUEUE BIT(13)

/* This last one is specific to EP0 */
#define DWC3_EP0_DIR_IN BIT(31)
@@ -1272,6 +1273,7 @@ struct dwc3 {
unsigned delayed_status:1;
unsigned ep0_bounced:1;
unsigned ep0_expect_in:1;
+ unsigned ep_dequeue_pending:1;
unsigned has_hibernation:1;
unsigned sysdev_is_parent:1;
unsigned has_lpm_erratum:1;
@@ -1553,6 +1555,7 @@ int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc);
void dwc3_ep0_stall_and_restart(struct dwc3 *dwc);
void dwc3_ep0_end_control_data(struct dwc3 *dwc, struct dwc3_ep *dep);
+int dwc3_gadget_check_ep_dequeue(struct dwc3 *dwc);
#else
static inline int dwc3_gadget_init(struct dwc3 *dwc)
{ return 0; }
@@ -1579,6 +1582,8 @@ static inline void dwc3_ep0_stall_and_restart(struct dwc3 *dwc)
static inline void dwc3_ep0_end_control_data(struct dwc3 *dwc,
struct dwc3_ep *dep)
{ }
+static inline int dwc3_gadget_check_ep_dequeue(struct dwc3 *dwc)
+{ return 0; }
#endif

#if IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)
diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index a2cc94c25dcf..99202f5a613e 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -243,6 +243,7 @@ void dwc3_ep0_stall_and_restart(struct dwc3 *dwc)

dwc->ep0state = EP0_SETUP_PHASE;
complete(&dwc->ep0_in_setup);
+ dwc3_gadget_check_ep_dequeue(dwc);
if (dwc->softconnect)
dwc3_ep0_out_start(dwc);
}
@@ -925,6 +926,7 @@ static void dwc3_ep0_complete_status(struct dwc3 *dwc,

dwc->ep0state = EP0_SETUP_PHASE;
complete(&dwc->ep0_in_setup);
+ dwc3_gadget_check_ep_dequeue(dwc);
if (dwc->softconnect)
dwc3_ep0_out_start(dwc);
}
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index f6801199440c..0c89baedf220 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -654,7 +654,7 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
return dwc3_send_gadget_ep_cmd(dep, DWC3_DEPCMD_SETEPCONFIG, &params);
}

-static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
+static int dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
bool interrupt);

/**
@@ -1081,6 +1081,31 @@ static int dwc3_gadget_ep_enable(struct usb_ep *ep,
return ret;
}

+int dwc3_gadget_check_ep_dequeue(struct dwc3 *dwc)
+{
+ struct dwc3_ep *dep;
+ int ret = 0;
+ int i;
+
+ if (!dwc->ep_dequeue_pending)
+ return 0;
+
+ for (i = 0; i < dwc->num_eps; i++) {
+ dep = dwc->eps[i];
+ if (dep->flags & DWC3_EP_PENDING_DEQUEUE) {
+ ret = dwc3_stop_active_transfer(dep, false, true);
+ if (ret)
+ goto exit;
+
+ dep->flags &= ~DWC3_EP_PENDING_DEQUEUE;
+ }
+ }
+
+ dwc->ep_dequeue_pending = 0;
+exit:
+ return ret;
+}
+
static int dwc3_gadget_ep_disable(struct usb_ep *ep)
{
struct dwc3_ep *dep;
@@ -2033,10 +2058,6 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
list_for_each_entry(r, &dep->started_list, list) {
if (r == req) {
struct dwc3_request *t;
-
- /* wait until it is processed */
- dwc3_stop_active_transfer(dep, true, true);
-
/*
* Remove any started request if the transfer is
* cancelled.
@@ -2045,6 +2066,12 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
dwc3_gadget_move_cancelled_request(r,
DWC3_REQUEST_STATUS_DEQUEUED);

+ ret = dwc3_stop_active_transfer(dep, false, true);
+ if (ret == -ETIMEDOUT) {
+ dep->flags |= DWC3_EP_PENDING_DEQUEUE;
+ dwc->ep_dequeue_pending = 1;
+ }
+
dep->flags &= ~DWC3_EP_WAIT_TRANSFER_COMPLETE;

goto out;
@@ -2319,6 +2346,7 @@ static void dwc3_stop_active_transfers(struct dwc3 *dwc)
continue;

dwc3_remove_requests(dwc, dep);
+ dep->flags &= ~DWC3_EP_PENDING_DEQUEUE;
}
}

@@ -2715,6 +2743,7 @@ static int __dwc3_gadget_start(struct dwc3 *dwc)
dwc->ep0state = EP0_SETUP_PHASE;
dwc->link_state = DWC3_LINK_STATE_SS_DIS;
dwc->delayed_status = false;
+ dwc->ep_dequeue_pending = 0;
dwc3_ep0_out_start(dwc);

dwc3_gadget_enable_irq(dwc);
@@ -3433,6 +3462,7 @@ static void dwc3_gadget_endpoint_command_complete(struct dwc3_ep *dep,
if (dep->stream_capable)
dep->flags |= DWC3_EP_IGNORE_NEXT_NOSTREAM;

+ dep->flags &= ~DWC3_EP_PENDING_DEQUEUE;
dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
dwc3_gadget_ep_cleanup_cancelled_requests(dep);
@@ -3609,7 +3639,7 @@ static void dwc3_reset_gadget(struct dwc3 *dwc)
}
}

-static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
+static int dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
bool interrupt)
{
struct dwc3_gadget_ep_cmd_params params;
@@ -3620,7 +3650,7 @@ static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,

if (!(dep->flags & DWC3_EP_TRANSFER_STARTED) ||
(dep->flags & DWC3_EP_END_TRANSFER_PENDING))
- return;
+ return 0;

/*
* NOTICE: We are violating what the Databook says about the
@@ -3671,6 +3701,8 @@ static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
dwc3_ep0_out_start(dwc);
goto retry;
}
+ } else {
+ return ret;
}
}
dep->resource_index = 0;
@@ -3679,6 +3711,7 @@ static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
else
dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
+ return ret;
}

static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)