Messages in this thread | | | Date | Thu, 12 Oct 2023 12:25:26 -0700 | Subject | Re: [RFC] usb: dwc3: core: Fix RAM interface getting stuck during enumeration | From | Wesley Cheng <> |
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Hi Krishna,
On 10/11/2023 3:02 AM, Krishna Kurapati wrote: > This implementation is to fix RAM interface getting stuck during > enumeration and controller not responding to any command. > > During plug-out test cases, it is sometimes seen that no events > are generated by the controller and all CSR register reads give "0" > and CSR_Timeout bit gets set indicating that CSR reads/writes are > timing out or timed out. > > The issue comes up on different instnaces of enumeration on different > platforms. On one platform, the debug log is as follows: > > Prepared a TRB on ep0out and did start transfer to get set > address request from host: > > <...>-7191 [000] D..1. 66.421006: dwc3_gadget_ep_cmd: ep0out: > cmd 'Start Transfer' [406] params 00000000 efffa000 00000000 --> > status: Successful > > <...>-7191 [000] D..1. 66.421196: dwc3_event: event (0000c040): > ep0out: Transfer Complete (sIL) [Setup Phase] > > <...>-7191 [000] D..1. 66.421197: dwc3_ctrl_req: Set > Address(Addr = 01) > > Then XFER NRDY received on ep0in for zero length status phase and > a Start Transfer was done on ep0in with 0-length packet in 2 Stage > status phase: > > <...>-7191 [000] D..1. 66.421249: dwc3_event: event (000020c2): > ep0in: Transfer Not Ready [00000000] (Not Active) [Status Phase] > > <...>-7191 [000] D..1. 66.421266: dwc3_prepare_trb: ep0in: trb > ffffffc00fcfd000 (E0:D0) buf 00000000efffa000 size 0 ctrl 00000c33 > sofn 00000000 (HLcs:SC:status2) > > <...>-7191 [000] D..1. 66.421387: dwc3_gadget_ep_cmd: ep0in: cmd > 'Start Transfer' [406] params 00000000 efffa000 00000000 -->status: > Successful > > Then a bus reset was received directly after 500 msec. Software never > got the cmd complete for the start transfer done in status phase. Here > the RAM interface is stuck. So host issues a bus reset as link is > idle for 500 msec: > > <...>-7191 [000] D..1. 66.935603: dwc3_event: event (00000101): > Reset [U0] > > Then software sees that it is in status phase and we issue an ENDXFER > on ep0in and it gets timedout waiting for the CMDACT to go '0': > > <...>-7191 [000] D..1. 66.958249: dwc3_gadget_ep_cmd: ep0in: cmd > 'End Transfer' [10508] params 00000000 00000000 00000000 --> status: > Timed Out > > Upon debug with Synopsys, it turns out that the root cause is as > follows: > > During any transfer, if the data is not successfully transmitted, > then a Done (with failure) handshake is returned, so that the BMU > can re-attempt the same data again by rewinding its data pointers. > > But, if the USB IN is a 0-length payload (which is what is happening > in this case - 2 stage status phase of set_address), then there is no > need to rewind the pointers and the Done (with failure) handshake is > not returned for failure case. This keeps the Request-Done interface > busy till the next Done handshake. The MAC sends the 0-length payload > again when the host requests. If the transmission is successful this > time, the Done (with success) handshake is provided back. Otherwise, > it repeats the same steps again. > > If the cable is disconnected or if the Host aborts the transfer on 3 > consecutive failed attempts, the Request-Done handshake is not > complete. This keeps the interface busy. > > The subsequent RAM access cannot proceed until the above pending > transfer is complete. This results in failure of any access to RAM > address locations. Many of the EndPoint commands need to access the > RAM and they would fail to complete successfully. > > Furthermore when cable removal happens, this would not generate a > disconnect event and the "connected" flag remains true always blockin > suspend. > > Synopsys confirmed that the issue is present on all USB3 devices and > as a workaround, suggested to re-initialize device mode. > > Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com> > --- > drivers/usb/dwc3/core.c | 20 ++++++++++++++++++++ > drivers/usb/dwc3/core.h | 4 ++++ > drivers/usb/dwc3/drd.c | 5 +++++ > drivers/usb/dwc3/gadget.c | 6 ++++-- > 4 files changed, 33 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c > index 44ee8526dc28..d18b81cccdc5 100644 > --- a/drivers/usb/dwc3/core.c > +++ b/drivers/usb/dwc3/core.c > @@ -122,6 +122,7 @@ static void __dwc3_set_mode(struct work_struct *work) > unsigned long flags; > int ret; > u32 reg; > + u8 timeout = 100; > u32 desired_dr_role; > > mutex_lock(&dwc->mutex); > @@ -137,6 +138,25 @@ static void __dwc3_set_mode(struct work_struct *work) > if (!desired_dr_role) > goto out; > > + /* > + * STAR 5001544 - If cable disconnect doesn't generate > + * disconnect event in device mode, then re-initialize the > + * controller. > + */ > + if ((dwc->cable_disconnected == true) && > + (dwc->current_dr_role == DWC3_GCTL_PRTCAP_DEVICE)) { > + while (dwc->connected == true && timeout != 0) { > + mdelay(10); > + timeout--; > + } > + > + if (timeout == 0) { > + dwc3_gadget_soft_disconnect(dwc); > + udelay(100); > + dwc3_gadget_soft_connect(dwc); > + } > + } > + > if (desired_dr_role == dwc->current_dr_role) > goto out; > > diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h > index c6c87acbd376..7642330cf608 100644 > --- a/drivers/usb/dwc3/core.h > +++ b/drivers/usb/dwc3/core.h > @@ -1355,6 +1355,7 @@ struct dwc3 { > int last_fifo_depth; > int num_ep_resized; > struct dentry *debug_root; > + bool cable_disconnected; > }; > > #define INCRX_BURST_MODE 0 > @@ -1568,6 +1569,9 @@ void dwc3_event_buffers_cleanup(struct dwc3 *dwc); > > int dwc3_core_soft_reset(struct dwc3 *dwc); > > +int dwc3_gadget_soft_disconnect(struct dwc3 *dwc); > +int dwc3_gadget_soft_connect(struct dwc3 *dwc); > + > #if IS_ENABLED(CONFIG_USB_DWC3_HOST) || IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE) > int dwc3_host_init(struct dwc3 *dwc); > void dwc3_host_exit(struct dwc3 *dwc); > diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c > index 039bf241769a..593c023fc39a 100644 > --- a/drivers/usb/dwc3/drd.c > +++ b/drivers/usb/dwc3/drd.c > @@ -446,6 +446,8 @@ static int dwc3_usb_role_switch_set(struct usb_role_switch *sw, > struct dwc3 *dwc = usb_role_switch_get_drvdata(sw); > u32 mode; > > + dwc->cable_disconnected = false; > + > switch (role) { > case USB_ROLE_HOST: > mode = DWC3_GCTL_PRTCAP_HOST; > @@ -454,6 +456,9 @@ static int dwc3_usb_role_switch_set(struct usb_role_switch *sw, > mode = DWC3_GCTL_PRTCAP_DEVICE; > break; > default: > + if (role == USB_ROLE_NONE) > + dwc->cable_disconnected = true; > +
How do we handle cases where role switch isn't used? (ie extcon or maybe no cable connection notification at all)
Thanks Wesley Cheng
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