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=-8.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 2C371C43457 for ; Wed, 14 Oct 2020 10:43:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D06AB22202 for ; Wed, 14 Oct 2020 10:43:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388364AbgJNKnv (ORCPT ); Wed, 14 Oct 2020 06:43:51 -0400 Received: from mga12.intel.com ([192.55.52.136]:12859 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730147AbgJNKnn (ORCPT ); Wed, 14 Oct 2020 06:43:43 -0400 IronPort-SDR: enc/vszMvt6+FN2C7aLOl7XMIubdZpwMuKrDZVq/0nZyXkG9OhrJME51fZpnvP2/xJTylYRR87 g4IrRXCSWLiw== X-IronPort-AV: E=McAfee;i="6000,8403,9773"; a="145391576" X-IronPort-AV: E=Sophos;i="5.77,374,1596524400"; d="scan'208";a="145391576" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2020 03:43:42 -0700 IronPort-SDR: 8wIME1GlY3GPDFzvauGIUIdcoh5YgtGDiqR8RW3Luq2f7r7X2NhaKLNT2UGDS/gTXPLrfwZvpo jYy6j5RFRRHQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,374,1596524400"; d="scan'208";a="357340046" Received: from mylly.fi.intel.com (HELO [10.237.72.56]) ([10.237.72.56]) by orsmga007.jf.intel.com with ESMTP; 14 Oct 2020 03:43:40 -0700 Subject: Re: [PATCH] i2c: designware: fix slave omitted IC_INTR_STOP_DET To: Michael Wu , Andy Shevchenko , Mika Westerberg , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Morgan Chang , Dean Hsiao , Paul Chen References: <20201014052532.3298-1-michael.wu@vatics.com> From: Jarkko Nikula Message-ID: Date: Wed, 14 Oct 2020 13:43:39 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201014052532.3298-1-michael.wu@vatics.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi On 10/14/20 8:25 AM, Michael Wu wrote: > When an I2C slave works, sometimes both IC_INTR_RX_FULL and > IC_INTR_STOP_DET are rising during an IRQ handle, especially when system > is busy or too late to handle interrupts. > > If IC_INTR_RX_FULL is rising and the system doesn't handle immediately, > IC_INTR_STOP_DET may be rising and the system has to handle these two > events. For this there may be two problems: > e > 1. IC_INTR_STOP_DET is rising after i2c_dw_read_clear_intrbits_slave() > done: It seems invalidated because WRITE_REQUESTED is done after the > 1st WRITE_RECEIVED. > > $ i2cset -f -y 2 0x42 0x00 0x41; dmesg -c > [0][clear_intrbits]0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x514 : INTR_STAT=0x4 > [1][irq_handler ]0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x514 : INTR_STAT=0x4 > WRITE_RECEIVED > [0][clear_intrbits]0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x514 : INTR_STAT=0x4 > [1][irq_handler ]0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x714 : INTR_STAT=0x204 > WRITE_REQUESTED > WRITE_RECEIVED > [0][clear_intrbits]0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x710 : INTR_STAT=0x200 > [1][irq_handler ]0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x510 : INTR_STAT=0x0 > STOP > [2][clear_intrbits]0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x510 : INTR_STAT=0x0 > > t1: ISR with the 1st IC_INTR_RX_FULL. > t2: Clear listed IC_INTR bits by i2c_dw_read_clear_intrbits_slave(). > t3: Enter i2c_dw_irq_handler_slave() and then do > i2c_slave_event(WRITE_RECEIVED) because > if (stat & DW_IC_INTR_RX_FULL). > t4: ISR with the 2nd IC_INTR_RX_FULL. > t5: Clear listed IC_INTR bits by i2c_dw_read_clear_intrbits_slave(), > while IC_INTR_STOP_DET has not risen yet. > t6: Enter i2c_dw_irq_handler_slave() and then IC_INTR_STOP_DET is > rising. i2c_slave_event(WRITE_REQUESTED) will be done first because > if ((stat & DW_IC_INTR_RX_FULL) && (stat & DW_IC_INTR_STOP_DET)) and > then doing i2c_slave_event(WRITE_RECEIVED). > t7: do i2c_slave_event(STOP) due to IC_INTR_STOP_DET not be cleared yet. > > 2. Both IC_INTR_STOP_DET and IC_INTR_RX_FULL are rising before > i2c_dw_read_clear_intrbits_slave(): STOP cannot wait because > IC_INTR_STOP_DET is cleared by i2c_dw_read_clear_intrbits_slave(). > > $ i2cset -f -y 2 0x42 0x00 0x41; dmesg -c > [0][clear_intrbits]0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x514 : INTR_STAT=0x4 > [1][irq_handler ]0x1 STATUS SLAVE_ACTIVITY=0x1 : RAW_INTR_STAT=0x514 : INTR_STAT=0x4 > WRITE_RECEIVED > [0][clear_intrbits]0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x714 : INTR_STAT=0x204 > [1][irq_handler ]0x1 STATUS SLAVE_ACTIVITY=0x0 : RAW_INTR_STAT=0x514 : INTR_STAT=0x4 > WRITE_RECEIVED > > t1: ISR with the 1st IC_INTR_RX_FULL. > t2: Clear listed IC_INTR bits by i2c_dw_read_clear_intrbits_slave(). > t3: Enter i2c_dw_irq_handler_slave() and then do > i2c_slave_event(WRITE_RECEIVED) because > if (stat & DW_IC_INTR_RX_FULL). > t4: ISR with both IC_INTR_STOP_DET and the 2nd IC_INTR_RX_FULL. > t5: Clear listed IC_INTR bits by i2c_dw_read_clear_intrbits_slave(). The > current IC_INTR_STOP_DET is cleared by this > i2c_dw_read_clear_intrbits_slave(). > t6: Enter i2c_dw_irq_handler_slave() and then do > i2c_slave_event(WRITE_RECEIVED) because > if (stat & DW_IC_INTR_RX_FULL). > t7: i2c_slave_event(STOP) never be done because IC_INTR_STOP_DET was > cleared in t5. > > In order to resolve these problems, i2c_dw_read_clear_intrbits_slave() > should be called only one time in ISR and take the returned stat to handle > those occurred events. > > Signed-off-by: Michael Wu > --- > drivers/i2c/busses/i2c-designware-slave.c | 79 ++++++++++++----------- > 1 file changed, 40 insertions(+), 39 deletions(-) > Thanks for the patch. I was thinking this too after your report but haven't found actually time to look at implementing it. But what I was thinking it is probably good to have two patches. First patch that changes only i2c_dw_read_clear_intrbits_slave() semantics so that it's called only once like here and second patch that does other logic changes. Makes easier to catch possible regressions I think. Jarkko