From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Gardner Subject: [PATCH] i2c: designware: must wait for enable Date: Wed, 14 Feb 2018 09:29:52 -0600 Message-ID: <1518622192-19700-1-git-send-email-gardner.ben@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: Received: from mail-io0-f195.google.com ([209.85.223.195]:45662 "EHLO mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031179AbeBNPaB (ORCPT ); Wed, 14 Feb 2018 10:30:01 -0500 Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Jarkko Nikula , linux-i2c@vger.kernel.org Cc: Ben Gardner , Andy Shevchenko , Mika Westerberg , =?UTF-8?q?Jos=C3=A9=20Roberto=20de=20Souza?= , "linux-stable #4 . 13+" One I2C bus on my Atom E3845 board has been broken since 4.9. It has two devices, both declared by ACPI and with built-in drivers. There are two back-to-back transactions originating from the kernel, one targeting each device. The first transaction works, the second one locks up the I2C controller. The controller never recovers. These kernel logs show up whenever an I2C transaction is attempted after this failure. i2c-designware-pci 0000:00:18.3: timeout in disabling adapter i2c-designware-pci 0000:00:18.3: timeout waiting for bus ready Waiting for the I2C controller status to indicate that it is enabled before programming it fixes the issue. I have tested this patch on 4.14 and 4.15. Fixes: commit 2702ea7dbec5 ("i2c: designware: wait for disable/enable only if necessary") Cc: linux-stable #4.13+ Cc: José Roberto de Souza Signed-off-by: Ben Gardner --- drivers/i2c/busses/i2c-designware-master.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c index ae69188..55926ef 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -209,7 +209,7 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev) i2c_dw_disable_int(dev); /* Enable the adapter */ - __i2c_dw_enable(dev, true); + __i2c_dw_enable_and_wait(dev, true); /* Clear and enable interrupts */ dw_readl(dev, DW_IC_CLR_INTR); -- 2.7.4