[pvrusb2] read attempt on video device leads to error messages

[Mike Isely]

On Sat, 15 Oct 2005, Lars Schillingmann wrote:

> Am Freitag, 14. Oktober 2005 23:28 schrieb Mike Isely:
>>> Ok, I removed the pcf8574 stuff from the kernel and it works!
>>> Playing around with it now...
>>
>> Glad to hear you got past this.
>>
>> Was pcf8574 part of the base kernel sources or was it something you had to
>> add?  I ask this because when I configure kernels for my own use, I
>> usually enable everything as modules in the build.  If it's there I can
>> try to reproduce the problem here.
>
> Should be in by default. The kernel options i had on before were:
> I2C_ALGOPCF
> I2C_ALGOPCA
>
> SENSORS_EEPROM
> SENSORS_PCF
> SENSORS_PCA95398574
> SENSORS_PCF8591
>
> You can find the options in device drivers -> i2c support ->
> {algorithms, Miscellaneous I2C Chip support}
>
> It was a messy setup there. It was leftover from a day when i played around
> with sensors and just activated stuff. It is not very easy to find
> information which sensor chipsets are on which hardware...
> I tried to reproduce this error by compiling the above options as modules. And
> loaded them before i loaded the pvrusb driver. But i could not reproduce the
> error that way. I only could reproduce it, when these drivers are compiled in
> the kernel. Maybe not all of them need to be.
>

This might have something to do with the order in which the I2C client 
drivers are polled, and that may have to do with how they have been 
loaded.

Try this:

Experiment #1:

   Unplug the PVR USB2 device

   modprobe -r saa7115
   modprobe -r pcf8574
   modprobe -r pvrusb2
   modprobe saa7115
   modprobe pcf8574

   Plug the device in.  Does it work?

Experiment #2:

   Unplug the PVR USB2 device

   modprobe -r saa7115
   modprobe -r pcf8574
   modprobe -r pvrusb2
   modprobe pcf8574
   modprobe saa7115

   Plug the device in.  Does it work?

The only difference here is the order of loading of saa7115 and pcf8574. 
You must make sure they're unloaded in order to affect their load order, 
and we're unloading pvrusb2 as well just 'cause we're paranoid...  In 
theory, one of those orders is going to work and the other will fail. 
Have you tried this?

I checked my kernel modules, and I happen have a pcf8574.ko sitting over 
here.  So I may try this experiment myself anyway - but right now I'm 
trying to focus on updating the ivtv modules within the driver and 
hopefully also dealing with issues involved in getting the driver to build 
under 2.6.14-rcwhatever.  So if you'd like to try that and save me some 
time...

   -Mike


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