From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Nikula Subject: Re: [PATCH] i2c: designware: must wait for enable Date: Thu, 15 Feb 2018 13:06:12 +0200 Message-ID: References: <1518622192-19700-1-git-send-email-gardner.ben@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: Received: from mga12.intel.com ([192.55.52.136]:31089 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755336AbeBOLFx (ORCPT ); Thu, 15 Feb 2018 06:05:53 -0500 In-Reply-To: <1518622192-19700-1-git-send-email-gardner.ben@gmail.com> Content-Language: en-US Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Ben Gardner , linux-i2c@vger.kernel.org Cc: Andy Shevchenko , Mika Westerberg , =?UTF-8?Q?Jos=c3=a9_Roberto_de_Souza?= , "linux-stable #4 . 13+" On 02/14/2018 05:29 PM, Ben Gardner wrote: > 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); > I believe this conversion was missing from commit 2702ea7dbec5 and regression is better to fix this way than reverting. We'll provide similar fix for for v4.9..v4.12. Code have had changes and renaming. Acked-by: Jarkko Nikula