Cardbus Fixes

I just checked into the tree some CardBus fixes. The biggest change was to the power-up sequence, as well as transitioning to using filters for the card change events. These two changes are somewhat intertwined, unfortunately, since the latter exposed some holes in the former. In a nutshell, we now register a filter for the card status change events. This means we can mark the card as bad right away before any additional interaction can happen to the card. We defer doing anything about the badness for a little bit (basically until the machine is idle enough for the cardbus kernel thread to run). The interlock mechanism is also much ligher weight, having moved from mutexes and CVs to simple msleeps. Fast interrupts require some care to get right, so I hope I've gotten it all right. The move is dictated by what you can and cannot do in a fast interrupt handler.

Before making these changes, my atheros card would often reset for no reason. After these changes, I've not had it reset until I started using a kernel without the changes. I'm not sure why this would make such a big difference, and I hate mysteries. They indicate that there's something I don't understand, which I also hate. I'd be interested to see if I still see this when the fully integrated code is committed and looped back (I have several trees, and I most frequently run an unmodified kernel from svn, but sometimes also run one of these trees). There's a small chance that one of my other local changes could be the cause, but given what they are it seems doubtful. Still, a good datapoint if it is.

In addition, these fixes add a retry option for the BadVcc errors that we'd see sometimes. These are annoying on some machines, and often times the best way to get around them was to reload the driver. They don't happen at all on TI based chipsets that I've seen (at least more recent ones). Instead, they were confined to the Ricoh chipsets. Since I switched my laptop a couple of years ago, I haven't seen them. These changes post-date the change, but have been tested lightly on another Ricoh laptop that I have. They've been heavily tested on the TI laptop. They are based only on the description of the problem in the NetBSD PR, since the implementations are so different for the different BSDs in this area.

Finally, I did some comment tweaking and shuffling. I also managed a style change or two. These should have absolutely no effect on the running code, but hopefully help the reader of the code understand it better. Past experience has shown that these types of commits are most likely to provoke comment, even though the other two parts of my commits are actually quite a bit more important.

Oh, why the flurry of commits? I was low on disk space, so I thought I'd go clean up. 11MB free just isn't enough. So I was looking around and discovered I still had a CVS tree and was going to blow it away. I did a final update just to see what changes I had. I'm glad I did, since I found these, and a few others. I still have more local changes there than I realized. Sometimes I guess it is good to run out of disk space and go on a cleaning spree? It also makes for smaller backups when you don't have top copy 5GB of /usr/obj and kernel build trees...