Re: [Openvortex-dev] Findings...

[Manuel Jander]

Hi,

> According "Linux Device Drivers, 2nd Ed.", the right way to handle IRQ
> grabbing is at the device's open() code--they also suggest that the
> IRQ should be released in the device's close() code as well which
> means you'd have to keep track of how many open()'s have happened and
>  
>
> how many close()'s before releasing the IRQ (keep a reference count).
>  

Please don't. That can be very messy. The ALSA driver tutorial 
recommends capturing
IRQ's on driver loading and release when the driver is released.
With all respect to Mister Rubini there would be no benefit doing as 
that book states
(in this case) and it would only increase the chance of having a IRQ or 
DMA or 
whatever event in an inapropiate state. You would have to mix up all 
interrupt stuff
of every PCM channel + MIDI ...
By the way, when calling the set hardware params ALSA call the IRQ 
PCMOUT source is
enabled, and disabled on the ALSA hardware release call.

> In this case, it sounds like it would be a good idea to do things this
> way for the au88x0 driver. That way the card would (ideally) be fully
> initialized before an IRQ can occur. As for badly designed Vortex
> cards, mine's revision FA, so that is a distinct possibility.  ;-(  At
> least now there is the possibility of finding these problems...  :-p
>  
No, please don't. I really disagree.
I do agree with initializing the card (reseting) before registering the 
IRQ handler.
That can be done by placing the vortex_core_init() call a few lines 
before. In my opinion
thats all whats needed to fix the problem, at it's real root (if our 
assumptions are true).

I really don't like having to disagree, but any changes that pursue a 
bug should be done
consistently. Changing all the driver would increase the chance of new 
bugs. And we first
have to be sure what is really causing the bug.

There are other areas (like the SRC) that require much more attention 
right now.

Best Regards

Manuel Jander.