[linux-dvb] Possible bug in dib0700_core.c i2c transfer function

Devin Heitmueller devin.heitmueller at gmail.com
Thu Aug 14 22:10:11 CEST 2008


On Thu, Aug 14, 2008 at 3:57 PM, Nicolas Will <nico at youplala.net> wrote:
> I cannot code or really understand the details, but could this explain
> the more or less regular i2c read failures or even write failures
> eventually leading to device lock-ups that we are still experiencing if
> we are a bit too agressive?

In regards to i2c and the dib0700, I am actually debugging two
independent issues.  One is the behavior I described above, where I
can clearly see i2c read requests being turned into i2c writes.  The
second is what I would describe as "intermittent i2c read and write
failures", where the dib0700 is returning "-32" to the request.

For example (taken from a USB bus capture attempt to set the xc5000
signal source via the dib0700):

d3cd8b00 1554060054 S Co:8:109:0 s 40 03 0000 0000 0006 6 = 03c8000d 0000
d3cd8b00 1554061321 C Co:8:109:0 -32 6 >

I figured I would start with the issue that seems pretty well
understood and reproducible before I start talking about the
flaky/intermittent i2c read/write failures.  Unfortunately I don't
have an i2c bus analyzer which would be useful to better understand
whether this is a failure in the dib0700, or whether the request is
being passed through to the xc5000 and the xc5000 is reporting the
failure.  Without the dib0700 datasheet, I don't know what the status
code means...

Devin

-- 
Devin J. Heitmueller
http://www.devinheitmueller.com
AIM: devinheitmueller



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