Re: [corrected get-bisect results]: DViCO FusionHDTV7 Dual Express I2C write failed

[Mark Zimmerman <markzimm@frii.com>]

On Sun, Feb 13, 2011 at 09:52:25AM -0500, Devin Heitmueller wrote:
> On Sun, Feb 13, 2011 at 9:47 AM, Mark Zimmerman <markzimm@frii.com> 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 <khali@linux-fr.org>
> > 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