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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 3BE77C46469 for ; Wed, 12 Sep 2018 08:26:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C445A20890 for ; Wed, 12 Sep 2018 08:26:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C445A20890 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kaod.org 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 S1727659AbeILN3w (ORCPT ); Wed, 12 Sep 2018 09:29:52 -0400 Received: from 11.mo6.mail-out.ovh.net ([188.165.38.119]:58600 "EHLO 11.mo6.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726442AbeILN3w (ORCPT ); Wed, 12 Sep 2018 09:29:52 -0400 X-Greylist: delayed 7829 seconds by postgrey-1.27 at vger.kernel.org; Wed, 12 Sep 2018 09:29:51 EDT Received: from player726.ha.ovh.net (unknown [10.109.143.220]) by mo6.mail-out.ovh.net (Postfix) with ESMTP id DADAB17C9CC for ; Wed, 12 Sep 2018 07:57:36 +0200 (CEST) Received: from zorba.kaod.org (LFbn-1-10605-110.w90-89.abo.wanadoo.fr [90.89.196.110]) (Authenticated sender: postmaster@kaod.org) by player726.ha.ovh.net (Postfix) with ESMTPSA id 5AAAA2A0098; Wed, 12 Sep 2018 07:57:24 +0200 (CEST) Subject: Re: [PATCH i2c-next v6] i2c: aspeed: Handle master/slave combined irq events properly To: Guenter Roeck , Joel Stanley Cc: Jae Hyun Yoo , linux-aspeed@lists.ozlabs.org, Vernon Mauery , OpenBMC Maillist , Brendan Higgins , Linux Kernel Mailing List , jarkko.nikula@linux.intel.com, James Feist , Linux ARM , linux-i2c@vger.kernel.org References: <20180823225731.19063-1-jae.hyun.yoo@linux.intel.com> <20180911183734.GA21976@roeck-us.net> <1f34fe8c-69ef-5f2d-25dc-d5f6037cc558@linux.intel.com> <20180911204107.GA26017@roeck-us.net> <20180911233302.GA18799@roeck-us.net> From: =?UTF-8?Q?C=c3=a9dric_Le_Goater?= Message-ID: Date: Wed, 12 Sep 2018 07:57:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180911233302.GA18799@roeck-us.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Ovh-Tracer-Id: 12308337782753168372 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedtjedrjeefgdduuddtucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuqfggjfdpvefjgfevmfevgfenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddm Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/12/2018 01:33 AM, Guenter Roeck wrote: > On Wed, Sep 12, 2018 at 08:23:29AM +0930, Joel Stanley wrote: >> On Wed, 12 Sep 2018 at 07:48, Jae Hyun Yoo wrote: >>> >>> On 9/11/2018 1:41 PM, Guenter Roeck wrote: >>>> On Tue, Sep 11, 2018 at 01:30:41PM -0700, Jae Hyun Yoo wrote: >> >>>>> I checked this patch again but it doesn't have any change that could >>>>> affect to the probing flow. I'll debug the issue on qemu 3.0 environment >>>>> and will share if I find something. >>>>> >>>> The problem may be that qemu and the new code disagree how interrupts >>>> should be generated and handled, and the new code does not handle the >>>> interrupts it receives from the simulated hardware. This will result >>>> in i2c device probe failure, which in turn can cause all kinds of >>>> problems. >>>> >>> >>> Yes, that makes sense. Looks like it should be reverted until the issue >>> is fixed. Will submit a patch to revert it. >> >> Let's not rush. The qemu model was written in order to allow us to >> test the kernel code, and was validated by the kernel driver we have. >> We've had situations in the past (with the i2c driver in fact) where a >> change in the driver required an update of the model to be more >> accurate. >> >> I suggest we wait until Cedric has a chance to look at the issue >> before reverting the patch. >> > > Looking into the patch, clearing the interrupt status at the end of an > interrupt handler is always suspicious and tends to result in race yes. That happened in the past with the I2C aspeed driver. I can not find the thread anymore but we had to move up the ack of the interrupts. QEMU tends to be much faster to fire interrupts than real HW. > conditions (because additional interrupts may have arrived while handling > the existing interrupts, or because interrupt handling itself may trigger > another interrupt). With that in mind, the following patch fixes the > problem for me. Acked-by: Cédric Le Goater Thanks, C. > Guenter > > --- > > diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c > index c258c4d9a4c0..c488e6950b7c 100644 > --- a/drivers/i2c/busses/i2c-aspeed.c > +++ b/drivers/i2c/busses/i2c-aspeed.c > @@ -552,6 +552,8 @@ 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 interrupt bits. */ > + writel(irq_received, bus->base + ASPEED_I2C_INTR_STS_REG); > irq_remaining = irq_received; > > #if IS_ENABLED(CONFIG_I2C_SLAVE) > @@ -584,8 +586,6 @@ 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); > spin_unlock(&bus->lock); > return irq_remaining ? IRQ_NONE : IRQ_HANDLED; > } >