From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2617AC433FE for ; Tue, 7 Sep 2021 07:28:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EB396109D for ; Tue, 7 Sep 2021 07:28:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233285AbhIGH3r (ORCPT ); Tue, 7 Sep 2021 03:29:47 -0400 Received: from fllv0015.ext.ti.com ([198.47.19.141]:49966 "EHLO fllv0015.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231161AbhIGH3q (ORCPT ); Tue, 7 Sep 2021 03:29:46 -0400 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id 1877Sa0Y005653; Tue, 7 Sep 2021 02:28:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1630999716; bh=2kavq6nJdZBNNM94n6MDZBgCMxqFqFaFHgQiAgBTqFk=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=dGNV9gIgmZz/+VuTqpQiFWnhqUvbVwNzvD+vW5Cpz0VIYUF318qYhHU9XaYXBe5dk 3MnPZnC2OfmkvgPuX1RrS1l66LXrmL8wzbkJ0SCFwEdDKjHmv11NTFNOzEgw53kjdV jmuFMPbMzMz5NTPDNYO92dJCk7pOMWz9izkuzBQI= Received: from DLEE106.ent.ti.com (dlee106.ent.ti.com [157.170.170.36]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 1877SaQp123467 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 7 Sep 2021 02:28:36 -0500 Received: from DLEE109.ent.ti.com (157.170.170.41) by DLEE106.ent.ti.com (157.170.170.36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.14; Tue, 7 Sep 2021 02:28:35 -0500 Received: from lelv0326.itg.ti.com (10.180.67.84) by DLEE109.ent.ti.com (157.170.170.41) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.14 via Frontend Transport; Tue, 7 Sep 2021 02:28:35 -0500 Received: from [10.250.232.51] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0326.itg.ti.com (8.15.2/8.15.2) with ESMTP id 1877SWW6054093; Tue, 7 Sep 2021 02:28:33 -0500 Subject: Re: [PATCH] usb: cdns3: fix race condition before setting doorbell To: Pawel Laszczak , CC: , , , , , References: <20210907062619.34622-1-pawell@gli-login.cadence.com> From: Aswath Govindraju Message-ID: <774df0ea-76e5-b8e2-9bd6-55e4b1cc09f4@ti.com> Date: Tue, 7 Sep 2021 12:58:32 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210907062619.34622-1-pawell@gli-login.cadence.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 07/09/21 11:56 am, Pawel Laszczak wrote: > From: Pawel Laszczak > > For DEV_VER_V3 version there exist race condition between clearing > ep_sts.EP_STS_TRBERR and setting ep_cmd.EP_CMD_DRDY bit. > Setting EP_CMD_DRDY will be ignored by controller when > EP_STS_TRBERR is set. So, between these two instructions we have > a small time gap in which the EP_STSS_TRBERR can be set. In such case > the transfer will not start after setting doorbell. > > Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver") > cc: # 5.12.x > Signed-off-by: Pawel Laszczak > --- Reviewed-by: Aswath Govindraju Tested-by: Aswath Govindraju > drivers/usb/cdns3/cdns3-gadget.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c > index 80aaab159e58..e9769fab21ea 100644 > --- a/drivers/usb/cdns3/cdns3-gadget.c > +++ b/drivers/usb/cdns3/cdns3-gadget.c > @@ -1100,6 +1100,19 @@ static int cdns3_ep_run_stream_transfer(struct cdns3_endpoint *priv_ep, > return 0; > } > > +static void cdns3_rearm_drdy_if_needed(struct cdns3_endpoint *priv_ep) > +{ > + struct cdns3_device *priv_dev = priv_ep->cdns3_dev; > + > + if (priv_dev->dev_ver < DEV_VER_V3) > + return; > + > + if (readl(&priv_dev->regs->ep_sts) & EP_STS_TRBERR) { > + writel(EP_STS_TRBERR, &priv_dev->regs->ep_sts); > + writel(EP_CMD_DRDY, &priv_dev->regs->ep_cmd); > + } > +} > + > /** > * cdns3_ep_run_transfer - start transfer on no-default endpoint hardware > * @priv_ep: endpoint object > @@ -1351,6 +1364,7 @@ static int cdns3_ep_run_transfer(struct cdns3_endpoint *priv_ep, > /*clearing TRBERR and EP_STS_DESCMIS before seting DRDY*/ > writel(EP_STS_TRBERR | EP_STS_DESCMIS, &priv_dev->regs->ep_sts); > writel(EP_CMD_DRDY, &priv_dev->regs->ep_cmd); > + cdns3_rearm_drdy_if_needed(priv_ep); > trace_cdns3_doorbell_epx(priv_ep->name, > readl(&priv_dev->regs->ep_traddr)); > } >