From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp02.frii.com ([216.17.135.168]:44805 "EHLO smtp02.frii.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754815Ab1BMU0p (ORCPT ); Sun, 13 Feb 2011 15:26:45 -0500 Date: Sun, 13 Feb 2011 13:26:44 -0700 From: Mark Zimmerman To: Devin Heitmueller Cc: linux-media@vger.kernel.org Subject: Re: [corrected get-bisect results]: DViCO FusionHDTV7 Dual Express I2C write failed Message-ID: <20110213202644.GA15282@io.frii.com> References: <20101207190753.GA21666@io.frii.com> <20110212152954.GA20838@io.frii.com> <20110213144758.GA79915@io.frii.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: List-ID: Sender: On Sun, Feb 13, 2011 at 09:52:25AM -0500, Devin Heitmueller wrote: > On Sun, Feb 13, 2011 at 9:47 AM, Mark Zimmerman wrote: > > Clearly my previous bisection went astray; I think I have a more > > sensible result this time. > > > > qpc$ git bisect good > > 44835f197bf1e3f57464f23dfb239fef06cf89be is the first bad commit > > commit 44835f197bf1e3f57464f23dfb239fef06cf89be > > Author: Jean Delvare > > Date: ? Sun Jul 18 16:52:05 2010 -0300 > > > > ? ?V4L/DVB: cx23885: Check for slave nack on all transactions > > > > ? ?Don't just check for nacks on zero-length transactions. Check on > > ? ?other transactions too. > > This could be a combination of the xc5000 doing clock stretching and > the cx23885 i2c master not properly implementing clock stretch. In > the past I've seen i2c masters broken in their handling of clock > stretching where they treat it as a NAK. > > The xc5000 being one of the few devices that actually does i2c clock > stretching often exposes cases where it is improperly implemented in > the i2c master driver (I've had to fix this with several bridges). > Thanks for your insight. I am looking at cx23885-i2c.c and there is no clock stretching logic in i2c_slave_did_ack(). Would this be the right place for it to be? Can you point me to an example of another driver that does it correctly? I really don't know what I am doing... -- Mark