> > From: Peter Chen [mailto:peter.chen@xxxxxxxxxxxxx] > > Sent: 2014年2月25日 12:19 > > To: Neil Zhang > > Cc: balbi@xxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; > > linux-usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > > Subject: Re: [PATCH 5/6] USB: gadget: mv_udc: workaroud for missing > > dTD > > > > On Mon, Feb 24, 2014 at 04:03:15PM +0800, Neil Zhang wrote: > > > There is an issue with the add dTD tripwire semaphore (ATDTW bit in > > > USBCMD register) that can cause the controller to ignore a dTD that > > > is added to a primed endpoint. When this happens, the software can > > > read the tripwire bit and the status bit at '1' even though the > > > endpoint is unprimed. > > > > > > After executing a dTD, the device controller endpoint state machine > > > executes a final read of the dTD terminate bit to check if the > > > application added a dTD to the linked list at the last moment. This > > > read is done in the finpkt_read_latest_next_td (44) state. After the > > > read is performed, if the terminate bit is still set, the state > > > machine moves to unprime the endpoint. The decision to unprime the > > > endpoint is done in the checkqh_decision (59) state, based on the > > > value of > > the terminate bit. > > > > > > Before reaching the checkqh_decision state, the state machine > > > traverses the writeqhtd_status (57), writeqh_status (56), and > > > release_prime_mask > > > (42) states. As shown in the waveform, the ep_addtd_tripwire_clr > > > signal is not set to clear the tripwire bit in these states. > > > > > > Signed-off-by: Neil Zhang <zhangwm@xxxxxxxxxxx> > > > --- > > > drivers/usb/gadget/mv_udc_core.c | 20 ++++++++++++++++++++ > > > 1 file changed, 20 insertions(+) > > > > > > diff --git a/drivers/usb/gadget/mv_udc_core.c > > > b/drivers/usb/gadget/mv_udc_core.c > > > index a620cff..8df8606 100644 > > > --- a/drivers/usb/gadget/mv_udc_core.c > > > +++ b/drivers/usb/gadget/mv_udc_core.c > > > @@ -196,7 +196,27 @@ static int process_ep_req(struct mv_udc *udc, > > > int > > index, > > > while (readl(&udc->op_regs->epstatus) & bit_pos) > > > udelay(1); > > > break; > > > + } else { > > > + if (!(readl(&udc->op_regs->epstatus) & bit_pos)) { > > > + /* The DMA engine thinks there is no more dTD */ > > > + curr_dqh->next_dtd_ptr = curr_dtd->dtd_next > > > + & EP_QUEUE_HEAD_NEXT_POINTER_MASK; > > > + > > > + /* clear active and halt bit */ > > > + curr_dqh->size_ioc_int_sts &= > > > + ~(DTD_STATUS_ACTIVE > > > + | DTD_STATUS_HALTED); > > > + > > > + /* Do prime again */ > > > + wmb(); > > > + writel(bit_pos, &udc->op_regs->epprime); > > > + while (readl(&udc->op_regs->epprime) & bit_pos) > > > + cpu_relax(); > > > + > > > + break; > > > + } > > > } > > > + > > > udelay(1); > > > } > > > > > > > Is it a chipidea IP issue? Any errate number for this issue? > > Does we need it for chipidea driver? > > > > Yes, I think so. > 9000531823 B2-Medium Adding a dTD to a Primed Endpoint May Not Get > Recognized > Impacted Configuration: All device mode configurations. > Thanks for your information. Peter -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
