cafe_ccic smbus issues

Andres Salomon dilinger at
Fri Apr 27 20:49:23 EDT 2007

Jonathan Corbet wrote:
> Andres Salomon <dilinger at> wrote:
>> Huh.  Note that uncommenting out the mdelays in cafe_ctlr_power_up()
>> causes the timeout errors to go away.  However, the camera still does
>> not display an image..
> OK...well....something has clearly changed.  Among other things, it
> seems that, somehow, the sensor is taking longer to get itself in order
> once the power goes on.
> After that, though, "does not display an image" is a bit of a vague
> description.  Is the controller returning blank images to the
> application, or do things just stop?  Is the interrupt count in
> /proc/interrupts going up?

/proc/interrupts is not going up.  The camera app shows just a blank
frame; sysctl-t shows that it's stuck in an ioctl, and the function that
it's stuck in is cafe_vidioc_dqbuf().  It's specifically stuck here:

                if (wait_event_interruptible(cam->iowait,

!list_empty(&cam->sb_full))) {
                        ret = -ERESTARTSYS;

The list never gets filled; that makes sense, if we never get an
interrupt (and thus cafe_frame_tasklet is never scheduled).

The question is now, why wouldn't we be seeing interrupts?

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