[pvrusb2] Ability to fully reset a PVRUSB2 Device

[isely at isely.net]

Hi Diego,

I am sorry.  I had gotten completely distracted away from this.

I just updated to the latest kernel and have confirmed that it's still 
getting an oops when the device is hot-unplugged.  I'm looking at it 
right now.  At first glance this looks like a fairly nasty tear-down 
race - which long ago didn't used to be there.  So there has to be some 
kind of environmental change leading to this behavior.

  -Mike

On Wed, 21 Aug 2019, Diego Rivera wrote:

> Hi, Mike!
> Any luck with this? I haven't poked you in some time so I figured I'd check to see if you've had the
> opportunity to debug this anymore, and if there's any way I can help with the process...
> Let me know!
> Cheers!
> 
> On Sat, 2019-04-20 at 20:16 -0600, Diego Rivera wrote:
> > This is the result of a 2nd attempt with a hot-unplug.  I don't see many differences beyond the
> > values of some registers changing between one instance and the other.
> > Cheers!
> > -- 
> > 
> > 
> > 
> > Diego Rivera
> > 
> > On Sat, 2019-04-20 at 20:09 -0600, Diego Rivera wrote:
> > > Guinea pig #1 responding as ordered, sir!
> > > ☺
> > > One is the kernel log from connection, the other is what happens if I try to do a modprobe
> > > -r.  I noticed there's a call trace with registers - I'm wondering if I need to add more symbols
> > > packages so that trace can be more verbose and offer up more info. Thoughts?
> > > Let me know if you want me to try anything else.  I'm going to produce the output now for hot-
> > > unplug of the same device, see how that differs.
> > > Cheers!
> > > -- 
> > > 
> > > 
> > > 
> > > Diego Rivera
> > > 
> > > On Sat, 2019-04-20 at 20:26 -0500, isely at isely.net wrote:
> > > > Status update.  Nothing really useful to report except that I am seeing some screwy behavior
> > > > just on hotplug / hotunplug operations with the device just sitting idle not being touched by
> > > > anything.  In this case I tested an old 29032 model - a very early module but it's a useful
> > > > test subject because it is simpler than the HVR-1950 yet still exercises most of the key
> > > > pieces of the driver.  I ran a freshly compiled 5.0.9 kernel (latest stable) for this test.
> > > > Sorry this has taken so long.  As was guessed earlier, I haven't worked on this in a very long
> > > > time and I had to unbox a lot of stuff.  I also spent far too much time today setting up a
> > > > separate purpose-built computer which I can trash / crash / hang with wild abandon without
> > > > losing anything of value.  This approach allows me to keep my dev environment on a machine
> > > > separate from the one that is running test kernels.
> > > > I was able to cleanly modprobe -r pvrusb2 every time so far, but if the issue is on the DVB
> > > > side of the fence, then the old 29032 model I've just tried won't exhibit that issue.  So a
> > > > lot more characterization to do.
> > > > Diego: It would useful if you could post to me the section of your /var/log/kern.log (or
> > > > equivalent) should all the kernel messages from the point when you plug in the device to when
> > > > the fireworks are happening after trying to tear down.  If I find that same pattern here then
> > > > we'll know for sure that we are chasing the same issue.
> > > >   -Mike
> 

-- 

Mike Isely
isely @ isely (dot) net
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