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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E90CC001E0 for ; Mon, 23 Oct 2023 11:32:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234096AbjJWLcL (ORCPT ); Mon, 23 Oct 2023 07:32:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52024 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230404AbjJWLcI (ORCPT ); Mon, 23 Oct 2023 07:32:08 -0400 Received: from out30-98.freemail.mail.aliyun.com (out30-98.freemail.mail.aliyun.com [115.124.30.98]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64867DF; Mon, 23 Oct 2023 04:32:05 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R941e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046056;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0Vukm8c._1698060721; Received: from 30.97.48.63(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Vukm8c._1698060721) by smtp.aliyun-inc.com; Mon, 23 Oct 2023 19:32:02 +0800 Message-ID: <27d2f363-e24a-736a-9c4e-cff79ff958e0@linux.alibaba.com> Date: Mon, 23 Oct 2023 19:32:17 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH V2 3/7] i2c: sprd: Use global variables to record I2C ack/nack status instead of local variables To: Huangzheng Lai , Andi Shyti Cc: Orson Zhai , Chunyan Zhang , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, huangzheng lai , Xiongpeng Wu References: <20231023081158.10654-1-Huangzheng.Lai@unisoc.com> <20231023081158.10654-4-Huangzheng.Lai@unisoc.com> From: Baolin Wang In-Reply-To: <20231023081158.10654-4-Huangzheng.Lai@unisoc.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/23/2023 4:11 PM, Huangzheng Lai wrote: > We found that when the interrupt bit of the I2C controller is cleared, > the ack/nack bit is also cleared at the same time. After clearing the > interrupt bit in sprd_i2c_isr(), incorrect ack/nack information will be > obtained in sprd_i2c_isr_thread(), resulting in incorrect communication > when nack cannot be recognized. To solve this problem, we used a global This is a hardware bug? > variable to record ack/nack information before clearing the interrupt > bit instead of a local variable. > > Fixes: 8b9ec0719834 ("i2c: Add Spreadtrum I2C controller driver") > Cc: # v4.14+ > Signed-off-by: Huangzheng Lai > --- > drivers/i2c/busses/i2c-sprd.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c > index aa602958d4fd..dec627ef408c 100644 > --- a/drivers/i2c/busses/i2c-sprd.c > +++ b/drivers/i2c/busses/i2c-sprd.c > @@ -85,6 +85,7 @@ struct sprd_i2c { > struct clk *clk; > u32 src_clk; > u32 bus_freq; > + bool ack_flag; > struct completion complete; > struct reset_control *rst; > u8 *buf; > @@ -119,6 +120,7 @@ static void sprd_i2c_clear_ack(struct sprd_i2c *i2c_dev) > { > u32 tmp = readl(i2c_dev->base + I2C_STATUS); > > + i2c_dev->ack_flag = 0; > writel(tmp & ~I2C_RX_ACK, i2c_dev->base + I2C_STATUS); > } > > @@ -393,7 +395,6 @@ static irqreturn_t sprd_i2c_isr_thread(int irq, void *dev_id) > { > struct sprd_i2c *i2c_dev = dev_id; > struct i2c_msg *msg = i2c_dev->msg; > - bool ack = !(readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK); Before this patch, we will re-read the ack bit form the register, but now we just read it in sprd_i2c_isr(). Is it possible that we will miss the ack bit? > u32 i2c_tran; > > if (msg->flags & I2C_M_RD) > @@ -409,7 +410,7 @@ static irqreturn_t sprd_i2c_isr_thread(int irq, void *dev_id) > * For reading data, ack is always true, if i2c_tran is not 0 which > * means we still need to contine to read data from slave. > */ > - if (i2c_tran && ack) { > + if (i2c_tran && i2c_dev->ack_flag) { > sprd_i2c_data_transfer(i2c_dev); > return IRQ_HANDLED; > } > @@ -420,7 +421,7 @@ static irqreturn_t sprd_i2c_isr_thread(int irq, void *dev_id) > * If we did not get one ACK from slave when writing data, we should > * return -EIO to notify users. > */ > - if (!ack) > + if (!i2c_dev->ack_flag) > i2c_dev->err = -EIO; > else if (msg->flags & I2C_M_RD && i2c_dev->count) > sprd_i2c_read_bytes(i2c_dev, i2c_dev->buf, i2c_dev->count); > @@ -437,7 +438,6 @@ static irqreturn_t sprd_i2c_isr(int irq, void *dev_id) > { > struct sprd_i2c *i2c_dev = dev_id; > struct i2c_msg *msg = i2c_dev->msg; > - bool ack = !(readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK); > u32 i2c_tran; > > if (msg->flags & I2C_M_RD) > @@ -456,7 +456,8 @@ static irqreturn_t sprd_i2c_isr(int irq, void *dev_id) > * means we can read all data in one time, then we can finish this > * transmission too. > */ > - if (!i2c_tran || !ack) { > + i2c_dev->ack_flag = !(readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK); > + if (!i2c_tran || !i2c_dev->ack_flag) { > sprd_i2c_clear_start(i2c_dev); > sprd_i2c_clear_irq(i2c_dev); > }