| Message ID | 20230413195317.7468-1-quic_wcheng@quicinc.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Avoid having pending end transfers on soft disconnect | expand |
Sorry please disregard this submission, tools used added improper stable tag. Thanks Wesley Cheng On 4/13/2023 12:53 PM, Wesley Cheng wrote: > In case there is a host which takes time to complete a SETUP transaction, > during the soft disconnect sequence multiple DWC3 EPs will have their > DWC3_EP_DELAY_STOP flag set w/o issuing the end transfer command. Once the > controller halt sequence occurs, the soft disconnect is successful, and > the subsequent soft connect will attempt to flush the pending end transfers. > > Soft disconnect sequence: > 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 > > Soft connect bug: > BUG: spinlock already unlocked on CPU > spin_bug+0x0 > dwc3_remove_requests+0x278 > dwc3_ep0_out_start+0xb0 > __dwc3_gadget_start+0x25c > > The bug occurs due to the flush of the pending end transfers, as the gadget > start routine is not held with a spinlock. However, if the DWC3_EP_DELAY_STOP > is set, it will call the giveback API, which attempts to unlock the dwc->lock. > Ideally, the DWC3 gadget should not have pending end transfers on a soft > connect, so fix this 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. > > Changes in v4: > - Added stable to patches that address the actual issue > - Re-ordered patch series to include the refactor change at the end to remove > any dependencies to the actual fix. > > Changes in v3: > - Removed fixes tag in the refactor change > > Wesley Cheng (3): > usb: dwc3: gadget: Stall and restart EP0 if host is unresponsive > usb: dwc3: gadget: Execute gadget stop after halting the controller > usb: dwc3: gadget: Refactor EP0 forced stall/restart into a separate > API > > drivers/usb/dwc3/gadget.c | 101 ++++++++++++++++++++++---------------- > 1 file changed, 58 insertions(+), 43 deletions(-) >
In case there is a host which takes time to complete a SETUP transaction, during the soft disconnect sequence multiple DWC3 EPs will have their DWC3_EP_DELAY_STOP flag set w/o issuing the end transfer command. Once the controller halt sequence occurs, the soft disconnect is successful, and the subsequent soft connect will attempt to flush the pending end transfers. Soft disconnect sequence: 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 Soft connect bug: BUG: spinlock already unlocked on CPU spin_bug+0x0 dwc3_remove_requests+0x278 dwc3_ep0_out_start+0xb0 __dwc3_gadget_start+0x25c The bug occurs due to the flush of the pending end transfers, as the gadget start routine is not held with a spinlock. However, if the DWC3_EP_DELAY_STOP is set, it will call the giveback API, which attempts to unlock the dwc->lock. Ideally, the DWC3 gadget should not have pending end transfers on a soft connect, so fix this 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. Changes in v4: - Added stable to patches that address the actual issue - Re-ordered patch series to include the refactor change at the end to remove any dependencies to the actual fix. Changes in v3: - Removed fixes tag in the refactor change Wesley Cheng (3): usb: dwc3: gadget: Stall and restart EP0 if host is unresponsive usb: dwc3: gadget: Execute gadget stop after halting the controller usb: dwc3: gadget: Refactor EP0 forced stall/restart into a separate API drivers/usb/dwc3/gadget.c | 101 ++++++++++++++++++++++---------------- 1 file changed, 58 insertions(+), 43 deletions(-)