Re: [PULL -- 5.1 REGRESSION] Bluetooth: btusb: request wake pin with NOAUTOEN

[Brian Norris]

On Tue, Apr 9, 2019 at 8:43 PM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> Either it's edge-triggered and you'll get one possibly spurious
> interrupt for an old issue, or it's level-triggered and setting up the
> hw should bring the irq line inactive and you'll be ok.

I think our key difference here is in how much we trust the device:
knowing the quality of the firmware running on some of these devices,
I wouldn't totally trust that they get it right. (It's not fatal if we
allow a buggy firmware to provide an occasional spurious wakeup, but
it's much less OK to allow it a window for flooding us with
interrupts.) So while your suggestion is indeed correct for
well-behaved devices, I think both approaches have value.

> But I've applied your patch for now simply because it seems to be a
> smaller change.

Awesome, thanks!

> But I think you should look into whether it can be fixed by just
> requesting the irq once the hardware is really up (which may indeed be
> as late as open time).

Yes, I will take a look at that for future release cycles. It's a nice
addition regardless, I think.

Brian