Hi Thinh,
On 4/3/2023 6:11 PM, Thinh Nguyen wrote:
On Fri, Mar 31, 2023, Wesley Cheng wrote:
It was observed that there are hosts that may complete pending SETUP
transactions before the stop active transfers and controller halt occurs,
leading to lingering endxfer commands on DEPs on subsequent pullup/gadget
start iterations.
Can you clarify this a bit further? Even though the controller is
halted, you still observed activity?
Yes...I didn't understand how that was possible either, but traces
clearly showed that the controller halt was successful even though there
were no endxfers issued on some EPs. Although, I can't say for certain
if those EPs were actively being used at that time.
dwc3_gadget_ep_disable name=ep8in flags=0x3009 direction=1
dwc3_gadget_ep_disable name=ep4in flags=1 direction=1
dwc3_gadget_ep_disable name=ep3out flags=1 direction=0
usb_gadget_disconnect deactivated=0 connected=0 ret=0
The sequence shows that the USB gadget disconnect (dwc3_gadget_pullup(0))
routine completed successfully, allowing for the USB gadget to proceed with
a USB gadget connect. However, if this occurs the system runs into an
issue where:
BUG: spinlock already unlocked on CPU
spin_bug+0x0
dwc3_remove_requests+0x278
dwc3_ep0_out_start+0xb0
__dwc3_gadget_start+0x25c
This is due to the pending endxfers, leading to gadget start (w/o lock
held) to execute the remove requests, which will unlock the dwc3 spinlock
as part of giveback.
To mitigate this, resolve the pending endxfers on the pullup disable path
by:
1. Re-locating the SETUP phase check after stop active transfers, since
that is where the DWC3_EP_DELAY_STOP is potentially set. This also allows
for handling of a host that may be unresponsive by using the completion
timeout to trigger the stall and restart for EP0.
2. Do not call gadget stop until the poll for controller halt is
completed. DEVTEN is cleared as part of gadget stop, so the intention to
allow ep0 events to continue while waiting for controller halt is not
happening.
Fixes: c96683798e27 ("usb: dwc3: ep0: Don't prepare beyond Setup stage")
Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
---
drivers/usb/dwc3/gadget.c | 101 ++++++++++++++++++++++----------------
1 file changed, 58 insertions(+), 43 deletions(-)
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 3c63fa97a680..9715de8e99bc 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -139,6 +139,24 @@ int dwc3_gadget_set_link_state(struct dwc3 *dwc, enum dwc3_link_state state)
return -ETIMEDOUT;
}
+static void dwc3_ep0_reset_state(struct dwc3 *dwc)
+{
+ unsigned int dir;
+
+ if (dwc->ep0state != EP0_SETUP_PHASE) {
+ dir = !!dwc->ep0_expect_in;
+ if (dwc->ep0state == EP0_DATA_PHASE)
+ dwc3_ep0_end_control_data(dwc, dwc->eps[dir]);
+ else
+ dwc3_ep0_end_control_data(dwc, dwc->eps[!dir]);
+
+ dwc->eps[0]->trb_enqueue = 0;
+ dwc->eps[1]->trb_enqueue = 0;
+
+ dwc3_ep0_stall_and_restart(dwc);
+ }
+}
+
Can we separate refactoring changes other functional changes? It's
difficult to review with too many things to keep track of.
Sure I can split this into another patch.
Thanks
Wesley Cheng
