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

[Mike Isely]

I just found a key clue in the log you sent:

   pvrusb2 i2c_attach [client=pcf8574 @ 0x21 id=0x3fe]

That's the pvrusb2 driver reporting the attachment of an I2C client to
itself at I2C address 0x21.  Only problem, that's the wrong client at that
address.  Here's what we should see (looking at a log I have):

   pvrusb2 i2c_attach [client=saa7115[50] @ 0x21 id=0xf1]
   pvrusb2 attaching saa7115 I2C client

The second line is the driver recognizing that it has recognized this
particular client.  You don't see that second line because the pvrusb2
driver didn't recognize this alien client.

We need to understand why a pcf8574 driver (whatever the heck that is) has
gotten in the way.  THIS is why we can't control the saa7115.  One thing
you can try to do is identify which kernel configuration option controls
the selecting of that I2C client and disable it.  Then let's see if things
work better.  I have no idea at all why that I2C client is jumping in and
spoiling the party.

FYI, the way all this I2C stuff works is that the pvrusb2 driver
implements an "I2C adapter" driver for its I2C bus inside the device, and
then it plugs that into the I2C core.  When the new adapter driver appears
in the I2C core, all client drivers will take notice and examine the new
bus to see if there's a device there it should be controlling.  Under
normal circumstances, msp3400.ko, tuner.ko and saa7115.ko will all see the
bus, spot their chips and attach.  But in this case, something called
pcf8574 is attaching in place of saa7115, occupying the bus address that
saa7115 is supposed to get.

I saw a problem similar to this back in March.  When you try to run the
pvrusb2 driver on an x-box, there's an I2C client driver there which
incorrectly sticks its nose into the pvrusb2's bus and screws things up.
In that case, there's a patch that has to be applied to the xbox
distribution to fix that problem.

  -Mike

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