From mboxrd@z Thu Jan 1 00:00:00 1970 From: Javier Martinez Canillas Subject: [PATCH] i2c: exynos5: Avoid transaction timeouts due TRANSFER_DONE_AUTO not set Date: Thu, 9 Mar 2017 11:05:33 -0300 Message-ID: <20170309140533.24618-1-javier@osg.samsung.com> Return-path: Received: from ec2-52-27-115-49.us-west-2.compute.amazonaws.com ([52.27.115.49]:49192 "EHLO osg.samsung.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754814AbdCIOF4 (ORCPT ); Thu, 9 Mar 2017 09:05:56 -0500 Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Inki Dae , Andi Shyti , Mauro Carvalho Chehab , Shuah Khan , Javier Martinez Canillas , Kukjin Kim , Wolfram Sang , linux-samsung-soc@vger.kernel.org, Krzysztof Kozlowski , linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org 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. Fixes: 7999eecb7e56 ("i2c: exynos5: fix arbitration lost handling") Signed-off-by: Javier Martinez Canillas Reviewed-by: Andrzej Hajda --- 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; -- 2.9.3