Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752903AbaBXIDb (ORCPT ); Mon, 24 Feb 2014 03:03:31 -0500 Received: from mx0a-0016f401.pphosted.com ([67.231.148.174]:47760 "EHLO mx0a-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752256AbaBXID2 (ORCPT ); Mon, 24 Feb 2014 03:03:28 -0500 From: Neil Zhang To: , , , CC: Neil Zhang Subject: [PATCH 5/6] USB: gadget: mv_udc: workaroud for missing dTD Date: Mon, 24 Feb 2014 16:03:15 +0800 Message-ID: <1393228996-14787-6-git-send-email-zhangwm@marvell.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1393228996-14787-1-git-send-email-zhangwm@marvell.com> References: <1393228996-14787-1-git-send-email-zhangwm@marvell.com> MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.11.87,1.0.14,0.0.0000 definitions=2014-02-23_03:2014-02-21,2014-02-23,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=7.0.1-1305240000 definitions=main-1402230265 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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); } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/