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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 A877CC83003 for ; Wed, 29 Apr 2020 08:13:36 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7D79D2083B for ; Wed, 29 Apr 2020 08:13:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="nR8yrCNt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7D79D2083B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=aspeedtech.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:In-Reply-To:References: Message-ID:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=WiwkJE1IIi5pT5pYHZ3Ulf5sCVivWEF/gL7IM0vljtk=; b=nR8yrCNtBPa/do T0T6UQvDufcc7ECcPCcDVZdvb2p+YDa4jBFptwElXGNdvnPuGlLRT7KI9YvmOtECnsYBieAqxcr3e vz8MlRMeRtcJBumRGnAillAhsxEVCPiLGm6MWXylI06lNquWP1clTVSh+9GmtZA1gmuqitlaIzqGo cJmx9ppktE2UTkoXzphf6P9AkAnF5cTBjiDzXRHefU7IfAn+DKecw1gZMSekaI2y7OBd9C99poimz ZuPAK0tpZqf54NgkKXOYZFJFhe5fPHQsu1h52dmlOE8zx+qq1r6sM89ad8OliqHTAt930yhP1Xzdi mLY7iVsHrrcoKPpYiS5Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jThqJ-0001UL-E5; Wed, 29 Apr 2020 08:13:19 +0000 Received: from twspam01.aspeedtech.com ([211.20.114.71]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jThqF-0001T6-8Y for linux-arm-kernel@lists.infradead.org; Wed, 29 Apr 2020 08:13:16 +0000 Received: from mail.aspeedtech.com (twmbx02.aspeed.com [192.168.0.24]) by twspam01.aspeedtech.com with ESMTP id 03T82qFe086043; Wed, 29 Apr 2020 16:02:52 +0800 (GMT-8) (envelope-from ryan_chen@aspeedtech.com) Received: from TWMBX02.aspeed.com (192.168.0.24) by TWMBX02.aspeed.com (192.168.0.24) with Microsoft SMTP Server (TLS) id 15.0.620.29; Wed, 29 Apr 2020 16:12:46 +0800 Received: from TWMBX02.aspeed.com ([fe80::997d:c0a7:f01f:e1a7]) by TWMBX02.aspeed.com ([fe80::997d:c0a7:f01f:e1a7%12]) with mapi id 15.00.0620.020; Wed, 29 Apr 2020 16:12:45 +0800 From: Ryan Chen To: Wolfram Sang Subject: RE: [PATCH v0 linux master] i2c/busses: Avoid i2c interrupt status clear race condition. Thread-Topic: [PATCH v0 linux master] i2c/busses: Avoid i2c interrupt status clear race condition. Thread-Index: AQHWHdeQ1mqTBOPAdE+n+yVhmYVsFKiPNOCAgACLErA= Date: Wed, 29 Apr 2020 08:12:45 +0000 Message-ID: <56add9c6e6b5410986325a1360466e4b@TWMBX02.aspeed.com> References: <20200429033737.2781-1-ryan_chen@aspeedtech.com> <20200429075357.GA1957@kunai> In-Reply-To: <20200429075357.GA1957@kunai> Accept-Language: zh-TW, en-US Content-Language: zh-TW X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [192.168.2.87] MIME-Version: 1.0 X-DNSRBL: X-MAIL: twspam01.aspeedtech.com 03T82qFe086043 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200429_011315_558177_05DED900 X-CRM114-Status: GOOD ( 13.64 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-aspeed@lists.ozlabs.org" , Andrew Jeffery , Benjamin Herrenschmidt , "openbmc@lists.ozlabs.org" , Brendan Higgins , "linux-kernel@vger.kernel.org" , Joel Stanley , "linux-arm-kernel@lists.infradead.org" , "linux-i2c@vger.kernel.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org -----Original Message----- From: Wolfram Sang [mailto:wsa@the-dreams.de] Sent: Wednesday, April 29, 2020 3:54 PM To: Ryan Chen Cc: Brendan Higgins ; Benjamin Herrenschmidt ; Joel Stanley ; Andrew Jeffery ; linux-i2c@vger.kernel.org; openbmc@lists.ozlabs.org; linux-arm-kernel@lists.infradead.org; linux-aspeed@lists.ozlabs.org; linux-kernel@vger.kernel.org Subject: Re: [PATCH v0 linux master] i2c/busses: Avoid i2c interrupt status clear race condition. On Wed, Apr 29, 2020 at 11:37:37AM +0800, ryan_chen wrote: > In AST2600 there have a slow peripheral bus between CPU and i2c > controller. > Therefore GIC i2c interrupt status clear have delay timing, when CPU > issue write clear i2c controller interrupt status. > To avoid this issue, the driver need have read after write clear at > i2c ISR. > > Signed-off-by: ryan_chen v0? is it a prototype? [Ryan Chen] It is not prototype it is official patch. And is there maybe a Fixes: tag for it? [Ryan Chen] Yes it is a fix patch. > --- > drivers/i2c/busses/i2c-aspeed.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/busses/i2c-aspeed.c > b/drivers/i2c/busses/i2c-aspeed.c index 07c1993274c5..f51702d86a90 > 100644 > --- a/drivers/i2c/busses/i2c-aspeed.c > +++ b/drivers/i2c/busses/i2c-aspeed.c > @@ -603,6 +603,7 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id) > /* Ack all interrupts except for Rx done */ > writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE, > bus->base + ASPEED_I2C_INTR_STS_REG); > + readl(bus->base + ASPEED_I2C_INTR_STS_REG); > irq_remaining = irq_received; > > #if IS_ENABLED(CONFIG_I2C_SLAVE) > @@ -645,9 +646,11 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id) > irq_received, irq_handled); > > /* Ack Rx done */ > - if (irq_received & ASPEED_I2CD_INTR_RX_DONE) > + if (irq_received & ASPEED_I2CD_INTR_RX_DONE) { > writel(ASPEED_I2CD_INTR_RX_DONE, > bus->base + ASPEED_I2C_INTR_STS_REG); > + readl(bus->base + ASPEED_I2C_INTR_STS_REG); > + } > spin_unlock(&bus->lock); > return irq_remaining ? IRQ_NONE : IRQ_HANDLED; } > -- > 2.17.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel