On Sun, Feb 13, 2011 at 04:26:50PM -0500, Andy Walls wrote: > On Sun, 2011-02-13 at 13:26 -0700, Mark Zimmerman wrote: > > 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@xxxxxxxx> 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@xxxxxxxxxxxx> > > > > 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, > > You don't have much hope of getting that right without the CX23885 > datasheet. > > Let's just get the bad commit reverted and into 2.6.38, and fix what > used to work for you. Doing a git bisect is enough work for anyone. > > I'll do a patch to revert the commit and ask it to be pulled for > 2.6.38-rc-whatever. I'll be sure to add a > > Bisected-by: Mark Zimmerman <markzimm@xxxxxxxx> > > tag to the patch. (The Linux Kernel devs understand the work involved > to do a bisection.) > > > Later, if I can work up a patch to deal with clock stretching properly, > I may ask you to test. > Thanks, that would be great. Meanwhile, I have built a 2.6.37 with the offending commit removed: git bisect reset git checkout v2.6.37 git revert 44835f197bf1e3f57464f23dfb239fef06cf89be and it seems to be working fine using both tuners: xc5000: waiting for firmware upload (dvb-fe-xc5000-1.6.114.fw)... xc5000: firmware read 12401 bytes. xc5000: firmware uploading... xc5000: firmware upload complete... xc5000: waiting for firmware upload (dvb-fe-xc5000-1.6.114.fw)... xc5000: firmware read 12401 bytes. xc5000: firmware uploading... xc5000: firmware upload complete... Thanks again -- Mark -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
