From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrzej Hajda Subject: Re: [PATCH v2] i2c: exynos5: fix arbitration lost handling Date: Thu, 09 Mar 2017 14:57:08 +0100 Message-ID: <2666bc34-b25d-d5f0-b13d-7f13248d1cda@samsung.com> References: <1487761474-11547-1-git-send-email-a.hajda@samsung.com> <2fb11816-85e7-14f6-7b61-5d3eba6096aa@osg.samsung.com> <7f287a39-a8a4-1b9d-2d9a-36e849bd726b@samsung.com> <20935f7d-a41c-2987-daea-50e4c3aa4ab6@samsung.com> <1a9ff664-9321-70db-3a69-8adc0e04dca5@osg.samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:44142 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754086AbdCIN5P (ORCPT ); Thu, 9 Mar 2017 08:57:15 -0500 In-reply-to: <1a9ff664-9321-70db-3a69-8adc0e04dca5@osg.samsung.com> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Javier Martinez Canillas , Wolfram Sang , Krzysztof Kozlowski , linux-i2c@vger.kernel.org, linux-samsung-soc@vger.kernel.org Cc: Bartlomiej Zolnierkiewicz , Marek Szyprowski , Andi Shyti On 09.03.2017 14:13, Javier Martinez Canillas wrote: > (...) > Sure, would something like the following work for you? > > >From cba9f00ee7c419cee5ff980b583d92092d3ceaac Mon Sep 17 00:00:00 2001 > From: Javier Martinez Canillas > Date: Thu, 9 Mar 2017 10:06:21 -0300 > Subject: [PATCH] i2c: exynos5: Avoid transaction timeouts due TRANSFER_DONE_AUTO not set > > After commit 7999eecb7e56 ("i2c: exynos5: fix arbitration lost handling"), > some I2C transactions are failing because the TRANSFER_DONE_AUTO field is > not set in the I2C_TRANS_STATUS register so the i2c->status value is left > to -EINVAL causing the i2c->msg_complete completion to never be signaled. > > For example, when reading the time of an I2C rtc on an Exynos5800 machine: > > $ cat /sys/class/rtc/rtc0/time > [ 25.924594] exynos5-hsi2c 12e10000.i2c: rx timeout > [ 65.028365] max77686-rtc max77802-rtc: Fail to read time reg(-22) > cat: /sys/class/rtc/rtc0/time: Invalid argument > > The Exynos5422 manual states clearly that most I2C_TRANS_STATUS reg bits > (including TRANSFER_DONE_AUTO) are cleared after the register is read. So > reading has side effects and should only be done if HSI2C_INT_I2C was set. > > Signed-off-by: Javier Martinez Canillas Looks OK, you can add Fixes tag and my Reviewed-by: Andrzej Hajda . Regards Andrzej > --- > drivers/i2c/busses/i2c-exynos5.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c > index cbd93ce0661f..736a82472101 100644 > --- a/drivers/i2c/busses/i2c-exynos5.c > +++ b/drivers/i2c/busses/i2c-exynos5.c > @@ -457,7 +457,6 @@ static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id) > > int_status = readl(i2c->regs + HSI2C_INT_STATUS); > writel(int_status, i2c->regs + HSI2C_INT_STATUS); > - trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS); > > /* handle interrupt related to the transfer status */ > if (i2c->variant->hw == HSI2C_EXYNOS7) { > @@ -482,11 +481,13 @@ static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id) > goto stop; > } > > + trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS); > if ((trans_status & HSI2C_MASTER_ST_MASK) == HSI2C_MASTER_ST_LOSE) { > i2c->state = -EAGAIN; > goto stop; > } > } else if (int_status & HSI2C_INT_I2C) { > + trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS); > if (trans_status & HSI2C_NO_DEV_ACK) { > dev_dbg(i2c->dev, "No ACK from device\n"); > i2c->state = -ENXIO;