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=-0.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,URIBL_SBL,URIBL_SBL_A autolearn=ham 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 4A15DFC6182 for ; Fri, 14 Sep 2018 16:31:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0EFB920861 for ; Fri, 14 Sep 2018 16:31:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0EFB920861 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728241AbeINVrC (ORCPT ); Fri, 14 Sep 2018 17:47:02 -0400 Received: from mga06.intel.com ([134.134.136.31]:45349 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726845AbeINVrC (ORCPT ); Fri, 14 Sep 2018 17:47:02 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Sep 2018 09:31:47 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,374,1531810800"; d="scan'208";a="80489367" Received: from yoojae-mobl1.amr.corp.intel.com (HELO [10.7.153.151]) ([10.7.153.151]) by FMSMGA003.fm.intel.com with ESMTP; 14 Sep 2018 09:28:43 -0700 Subject: Re: [PATCH] i2c: aspeed: Acknowledge most interrupts early in interrupt handler To: Guenter Roeck , Brendan Higgins Cc: linux-aspeed@lists.ozlabs.org, Andrew Jeffery , openbmc@lists.ozlabs.org, linux-kernel@vger.kernel.org, =?UTF-8?Q?C=c3=a9dric_Le_Goater?= , linux-i2c@vger.kernel.org References: <1536895810-28903-1-git-send-email-linux@roeck-us.net> From: Jae Hyun Yoo Message-ID: Date: Fri, 14 Sep 2018 09:28:43 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1536895810-28903-1-git-send-email-linux@roeck-us.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/13/2018 8:30 PM, Guenter Roeck wrote: > Commit 3e9efc3299dd ("i2c: aspeed: Handle master/slave combined irq events > properly") moved interrupt acknowledgment to the end of the interrupt > handler. In part this was done because the AST2500 datasheet says: > > I2CD10 Interrupt Status Register > bit 2 Receive Done Interrupt status > S/W needs to clear this status bit to allow next data receiving. > > Acknowledging Receive Done before receive data was handled resulted in > receive errors on high speed I2C busses. > > However, interrupt acknowledgment was not only moved to the end of the > interrupt handler for Receive Done Interrupt status, but for all interrupt > status bits. This could result in race conditions if a second interrupt was > received during interrupt handling and not handled but still acknowledged > at the end of the interrupt handler. > > Acknowledge only "Receive Done Interrupt status" late in the interrupt > handler to solve the problem. > > Fixes: 3e9efc3299dd ("i2c: aspeed: Handle master/slave combined irq events properly") > Cc: Jae Hyun Yoo > Cc: Joel Stanley > Signed-off-by: Guenter Roeck > --- > drivers/i2c/busses/i2c-aspeed.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c > index c258c4d9a4c0..3d518e09369f 100644 > --- a/drivers/i2c/busses/i2c-aspeed.c > +++ b/drivers/i2c/busses/i2c-aspeed.c > @@ -552,6 +552,9 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id) > > spin_lock(&bus->lock); > irq_received = readl(bus->base + ASPEED_I2C_INTR_STS_REG); > + /* Ack all interrupts except for Rx done */ > + writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE, > + bus->base + ASPEED_I2C_INTR_STS_REG); > irq_remaining = irq_received; > > #if IS_ENABLED(CONFIG_I2C_SLAVE) > @@ -584,8 +587,10 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id) > "irq handled != irq. expected 0x%08x, but was 0x%08x\n", > irq_received, irq_handled); > > - /* Ack all interrupt bits. */ > - writel(irq_received, bus->base + ASPEED_I2C_INTR_STS_REG); > + /* Ack Rx done */ > + if (irq_received & ASPEED_I2CD_INTR_RX_DONE) > + writel(ASPEED_I2CD_INTR_RX_DONE, > + bus->base + ASPEED_I2C_INTR_STS_REG); > spin_unlock(&bus->lock); > return irq_remaining ? IRQ_NONE : IRQ_HANDLED; > } > Looks good to me. Thanks! :) Acked-by: Jae Hyun Yoo