Hello, I am writing a functionfs-based gadget, using the raspberry pi zero. Depending on the time my userland process takes between the moment the UDC is bound to the gadget and the moment it submits AIO transfers, it either works as expected or results in immediate transfer completion with status -11 (-EAGAIN). Enabling dynamic debug, I see the dev_dbg(hs->dev, "%s: submit request only in active state\n", line being output when this issue occurs (see log extract at the end of this email - note the 4 seconds gap between GINTSTS_ErlySusp - whatever that means - and io happening and being rejected). While I am sure there are hardware-dependent reasons to reject these transfers, and while I can shift processing around to reduce this delay and (apparently) reliably avoid this error, I think it is making using this UDC rather hard: if my understanding is correct, this is a race between userland and the bus. If the HCI suspends the bus first, I cannot even submit buffers to be ready to receive some future OUT transfer, but if the userland submits these buffers before suspension then they are accepted - even if they get filled hours later. In my case, the IN transfer is on an interrupt endpoint, so I also think it would make more sense for the UDC to accept it: then, data is ready for whenever the host wakes the bus and polls for interrupt transfers. Being a very occasional kernel contributor, have no immediate idea on how both sides could be conciliated, so this is more a "I noticed that it could be more convenient if..." than a proper bug report. Checking the dwc3 I do not identify such EAGAIN in its io submission code, and I did not (yet ?) trigger such error on my Intel Edison. Dec 24 12:29:19 sushi kernel: [218828.497937] dwc2 20980000.usb: ep0 state:1 Dec 24 12:29:19 sushi kernel: [218828.497948] dwc2 20980000.usb: dwc2_hsotg_start_req: DxEPCTL=0x84028000 Dec 24 12:29:19 sushi kernel: [218828.497959] dwc2 20980000.usb: dwc2_hsotg_start_req: DXEPCTL=0x80008000 Dec 24 12:29:19 sushi kernel: [218828.497984] dwc2 20980000.usb: dwc2_hsotg_irq: 04048028 00040000 (d0bc3cc4) retry 8 Dec 24 12:29:19 sushi kernel: [218828.497996] dwc2 20980000.usb: dwc2_hsotg_irq: daint=00000001 Dec 24 12:29:19 sushi kernel: [218828.498008] dwc2 20980000.usb: dwc2_hsotg_epint: ep0(in) DxEPINT=0x00000001 Dec 24 12:29:19 sushi kernel: [218828.498022] dwc2 20980000.usb: dwc2_hsotg_epint: XferCompl: DxEPCTL=0x00008000, DXEPTSIZ=00000000 Dec 24 12:29:19 sushi kernel: [218828.498034] dwc2 20980000.usb: dwc2_hsotg_complete_in: adjusting size done 0 => 36 Dec 24 12:29:19 sushi kernel: [218828.498046] dwc2 20980000.usb: req->length:36 req->actual:36 req->zero:1 Dec 24 12:29:19 sushi kernel: [218828.498056] dwc2 20980000.usb: Receiving zero-length packet on ep0 Dec 24 12:29:19 sushi kernel: [218828.498078] dwc2 20980000.usb: dwc2_hsotg_irq: 04088028 00080000 (d0bc3cc4) retry 8 Dec 24 12:29:19 sushi kernel: [218828.498089] dwc2 20980000.usb: dwc2_hsotg_irq: daint=00010000 Dec 24 12:29:19 sushi kernel: [218828.498101] dwc2 20980000.usb: dwc2_hsotg_epint: ep0(out) DxEPINT=0x00000001 Dec 24 12:29:19 sushi kernel: [218828.498113] dwc2 20980000.usb: dwc2_hsotg_epint: XferCompl: DxEPCTL=0x00028000, DXEPTSIZ=20000000 Dec 24 12:29:19 sushi kernel: [218828.498122] dwc2 20980000.usb: zlp packet received Dec 24 12:29:19 sushi kernel: [218828.498138] dwc2 20980000.usb: complete: ep 42dd5aad ep0, req 29f392ab, 0 => 5c316413 Dec 24 12:29:19 sushi kernel: [218828.498152] dwc2 20980000.usb: dwc2_hsotg_enqueue_setup: queueing setup request Dec 24 12:29:19 sushi kernel: [218828.498169] dwc2 20980000.usb: ep0: req 8e14c7b2: 8@d91bfc39, noi=0, zero=0, snok=0 Dec 24 12:29:19 sushi kernel: [218828.498186] dwc2 20980000.usb: dwc2_hsotg_start_req: DxEPCTL=0x00028000, ep 0, dir out Dec 24 12:29:19 sushi kernel: [218828.498198] dwc2 20980000.usb: ureq->length:8 ureq->actual:0 Dec 24 12:29:19 sushi kernel: [218828.498212] dwc2 20980000.usb: dwc2_hsotg_start_req: 1@8/8, 0x00080008 => 0x00000b10 Dec 24 12:29:19 sushi kernel: [218828.498225] dwc2 20980000.usb: dwc2_hsotg_start_req: 0x54ab8a20 => 0x00000b14 Dec 24 12:29:19 sushi kernel: [218828.498235] dwc2 20980000.usb: ep0 state:0 Dec 24 12:29:19 sushi kernel: [218828.498245] dwc2 20980000.usb: dwc2_hsotg_start_req: DxEPCTL=0x80028000 Dec 24 12:29:19 sushi kernel: [218828.498256] dwc2 20980000.usb: dwc2_hsotg_start_req: DXEPCTL=0x80028000 Dec 24 12:29:22 sushi kernel: [218830.967016] dwc2 20980000.usb: dwc2_hsotg_irq: 04008428 00000400 (d0bc3cc4) retry 8 Dec 24 12:29:22 sushi kernel: [218830.967035] dwc2 20980000.usb: GINTSTS_ErlySusp Dec 24 12:29:22 sushi kernel: [218830.970039] dwc2 20980000.usb: dwc2_hsotg_irq: 04008028 00000000 (d0bc3cc4) retry 8 Dec 24 12:29:25 sushi kernel: [218834.485152] dwc2 20980000.usb: ep1out: req 91851ac5: 10240@e55aa59c, noi=0, zero=0, snok=0 Dec 24 12:29:25 sushi kernel: [218834.485172] dwc2 20980000.usb: dwc2_hsotg_ep_queue: submit request only in active state Dec 24 12:29:25 sushi kernel: [218834.485261] dwc2 20980000.usb: ep1out: req 91851ac5: 10240@e55aa59c, noi=0, zero=0, snok=0 Dec 24 12:29:25 sushi kernel: [218834.485273] dwc2 20980000.usb: dwc2_hsotg_ep_queue: submit request only in active state Dec 24 12:29:25 sushi kernel: [218834.515516] dwc2 20980000.usb: ep2in: req 91851ac5: 2@8925e53a, noi=0, zero=0, snok=0 Dec 24 12:29:25 sushi kernel: [218834.515536] dwc2 20980000.usb: dwc2_hsotg_ep_queue: submit request only in active state Dec 24 12:29:31 sushi kernel: [218840.337809] dwc2 20980000.usb: dwc2_hsotg_pullup: is_on: 0 op_state: 3 Dec 24 12:29:31 sushi kernel: [218840.337844] dwc2 20980000.usb: complete: ep 42dd5aad ep0, req 8e14c7b2, -108 => 97e9bd28 Dec 24 12:29:31 sushi kernel: [218840.337865] dwc2 20980000.usb: dwc2_hsotg_complete_setup: failed -108 Regards, -- Vincent Pelletier
