Trying to debug interrupt flood after unbind

Rob Groner rgroner at
Thu Jun 2 11:02:53 EDT 2016

On Thu, 2016-06-02 at 10:38 +0100, Sudip Mukherjee wrote:
> On Tue, May 31, 2016 at 04:38:37PM -0400, Rob Groner wrote:
> > On Tue, 2016-05-31 at 13:14 -0700, Greg KH wrote:
> > > On Tue, May 31, 2016 at 06:41:24PM +0000, Rob Groner wrote:
> > > > I am trying to load a driver for an Exar serial chip, but that chip is gobbled
> > > > up by the 8250 driver on boot.
> > > 
> > > Why does the in-kernel driver not support this chip?  Do you have a
> > > pointer to the Exar source anywhere?
> > 
> > This is kind of an ongoing topic since around December.
> yes, and new driver was provided to have the gpio as a separate platform
> driver which was also tested by Rob and he confirmed that everything is
> working as expected. But the reviews asked for a total rewrite with the
> exar codes split out from 8250_pci, and i got busy with a change of
> dayjob. If you want to have a look at the final version that was
> submitted then it is at:

> I thought to do it this weekend but I will be again travelling to UK
> this weekend so again postponed for atleast one month.

I have no criticism or complaint for how long it is taking or will take
to get the in-kernel driver in good working order...I greatly appreciate
all of the help that has been given and offered.

What I'm trying to do is come up with a working alternative until the
driver fix is in.  In my perfect world, there would be a way for them to
disentangle the Exar chip from the 8250 driver, and then they could use
the provided Exar driver (until such time as the built-in driver does
everything needed).

Is there any other workaround other than "unbind"?  Because unbind
doesn't work for some reason.  And if there is no other alternative to
unbind, then is there some way I can try to identify where the interrupt
flood is coming from when I use it?  I've looked at the Exar driver, and
when it receives the interrupt, it checks all of its registers, and if
there is no interrupt bit there, it says "not mine", which is either
true or not true.  I'll investigate that possibility.


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