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mzOffline
Post subject: RE: I2C write failure in kernel 2.6.36-1.slh.2-a  PostPosted: 12.02.2011, 15:33



Joined: 2010-09-11
Posts: 57

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I just sent this to linux-media@vger.kernel.org:
      Code:
82ce67bf262b3f47ecb5a0ca31cace8ac72b7c98 is the first bad commit
commit 82ce67bf262b3f47ecb5a0ca31cace8ac72b7c98
Author: Jarod Wilson <jarod>
Date:   Thu Jul 29 18:20:44 2010 -0300

    V4L/DVB: staging/lirc: fix non-CONFIG_MODULES build horkage
   
    Fix when CONFIG_MODULES is not enabled:
   
    drivers/staging/lirc/lirc_parallel.c:243: error: implicit declaration of function 'module_refcount'
    drivers/staging/lirc/lirc_it87.c:150: error: implicit declaration of function 'module_refcount'
    drivers/built-in.o: In function `it87_probe':
    lirc_it87.c:(.text+0x4079b0): undefined reference to `init_chrdev'
    lirc_it87.c:(.text+0x4079cc): undefined reference to `drop_chrdev'
    drivers/built-in.o: In function `lirc_it87_exit':
    lirc_it87.c:(.exit.text+0x38a5): undefined reference to `drop_chrdev'
   
    Its a quick hack and untested beyond building, since I don't have the
    hardware, but it should do the trick.
   
    Acked-by: Randy Dunlap <randy>
    Signed-off-by: Jarod Wilson <jarod>
    Signed-off-by: Mauro Carvalho Chehab <mchehab>

:040000 040000 f645b46a07b7ff87a2c11ac9296a5ff56e89a0d0 49e50945ccf8e1c8567c049908890d2752443b72 M      drivers

However, this seems to involve changes only to staging, which I have turned off, so I am confused.
 
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dptOffline
Post subject: RE: I2C write failure in kernel 2.6.36-1.slh.2-a  PostPosted: 12.02.2011, 15:57



Joined: 2010-09-11
Posts: 281
Location: New Delhi
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I2C, as I know, is a serial data transfer (half-duplex) bus from Philips using one SDA (for data either way),and one SCL (clock provided by Master)connection (+ground). With multiple Masters, proper arbitration is needed (software).

EDIT: Post not related to problem, but not deleting post. Time for me to take a break and reset brain.

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Last edited by dpt on 13.02.2011, 04:17; edited 1 time in total
 
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slhOffline
Post subject: RE: I2C write failure in kernel 2.6.36-1.slh.2-a  PostPosted: 12.02.2011, 16:51



Joined: 2010-08-25
Posts: 747

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That particular commit cannot be responsible for your issues, as it's neither compiled with staging disabled nor has any relation to i2c or deeper kernel functions. Therefore you most likely stumbled over a false negative during your testing, which is a real issue for "fuzzy" and not 100% reliably reproducible symptoms and easily leads to wrong conclusions.
 
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mzOffline
Post subject: RE: I2C write failure in kernel 2.6.36-1.slh.2-a  PostPosted: 13.02.2011, 14:56



Joined: 2010-09-11
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I think I made a mistake in testing. After a do-over, I have a more sensible result.
      Code:
44835f197bf1e3f57464f23dfb239fef06cf89be is the first bad commit
commit 44835f197bf1e3f57464f23dfb239fef06cf89be
Author: Jean Delvare <khali>
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.
   
    Signed-off-by: Jean Delvare <khali>
    Signed-off-by: Andy Walls <awalls>
    Signed-off-by: Mauro Carvalho Chehab <mchehab>

:040000 040000 e48c9f6efc6186800e8d711c05987c0ad9445c09 1ba37458c6a5fc22d19271f09cde2f336887c616 M      drivers

More details here:
http://www.mail-archive.com/linux-media@vger.kernel.org/msg28030.html
 
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slhOffline
Post subject: RE: I2C write failure in kernel 2.6.36-1.slh.2-a  PostPosted: 13.02.2011, 14:59



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Yep, that looks a lot more like a potential culprit.
 
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mzOffline
Post subject: RE: I2C write failure in kernel 2.6.36-1.slh.2-a  PostPosted: 14.02.2011, 01:06



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It looks like they intend to revert that commit from 2.6.38-rc? (follow the email thread above). Meanwhile, I have built a 2.6.37 kernel with that commit reverted and it is working for me. If you (slh) choose to revert it from a 2.6.37 aptosid kernel then please make a note of that here and I will try it out.
 
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slhOffline
Post subject: RE: I2C write failure in kernel 2.6.36-1.slh.2-a  PostPosted: 16.02.2011, 01:55



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please test 2.6.37-25.
 
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mzOffline
Post subject: Re: RE: I2C write failure in kernel 2.6.36-1.slh.2-a  PostPosted: 16.02.2011, 05:20



Joined: 2010-09-11
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      slh wrote:
please test 2.6.37-25.

Both tuners are working perfectly now. Thanks for the new kernel; I think this issue is finally fixed.
      Code:
qpc$ uname -a
Linux qpc 2.6.37-0.slh.25-aptosid-amd64 #1 SMP PREEMPT Wed Feb 16 01:06:18 UTC 2011 x86_64 GNU/Linux
qpc$ dmesg | tail
[   19.072186] CE: hpet2 increased min_delta_ns to 7500 nsec
[   19.072197] CE: hpet2 increased min_delta_ns to 11250 nsec
[   36.426011] xc5000: waiting for firmware upload (dvb-fe-xc5000-1.6.114.fw)...
[   36.435742] xc5000: firmware read 12401 bytes.
[   36.435745] xc5000: firmware uploading...
[   37.990224] xc5000: firmware upload complete...
[   47.759589] xc5000: waiting for firmware upload (dvb-fe-xc5000-1.6.114.fw)...
[   47.762405] xc5000: firmware read 12401 bytes.
[   47.762406] xc5000: firmware uploading...
[   49.306768] xc5000: firmware upload complete...
 
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