From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: Re: [PATCH] i2c: designware: prevent early stop on TX FIFO empty Date: Wed, 19 Nov 2014 16:18:34 +0200 Message-ID: <20141119141834.GJ1309@lahna.fi.intel.com> References: <545CB6C4.8010201@arm.com> <20141119092122.GC1439@katana> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20141119092122.GC1439@katana> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: Andrew Jackson , Andrew Morton , Baruch Siach , "Du, Wenkai" , Shinya Kuribayashi , Romain Baeriswyl , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Liviu Dudau , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: linux-i2c@vger.kernel.org On Wed, Nov 19, 2014 at 10:21:22AM +0100, Wolfram Sang wrote: > On Fri, Nov 07, 2014 at 12:10:44PM +0000, Andrew Jackson wrote: > > If the Designware core is configured with IC_EMPTYFIFO_HOLD_MASTER_EN > > set to zero, allowing the TX FIFO to become empty causes a STOP > > condition to be generated on the I2C bus. If the transmit FIFO > > threshold is set too high, an erroneous STOP condition can be > > generated on long transfers - particularly where the interrupt > > latency is extended. Makes sense to give some slack so that the interrupt handler is still able to fill the FIFO. > > > > Signed-off-by: Andrew Jackson > > Signed-off-by: Liviu Dudau > > So, what do other designware users think of this change (nice CC list > BTW, Andrew). Adding Mika, too. I quickly tested this on Haswell machine with touch screen connected to the I2C bus and it still works fine, so Tested-by: Mika Westerberg