BBB @ 1Ghz hangs with 10-STABLE (11-CURRENT is ok)

[Winston Smith]

On Wed, Apr 30, 2014 at 6:41 PM, Ian Lepore <ian at freebsd.org> wrote:
> That backtrace is just the idle thread; usually that's a sign that some
> device driver is waiting for an interrupt to finish configuring the
> device and it never gets it and just hangs.

In cases like this, what should I be collecting? (assuming I can break
into the debugger)

> Often usb is the culprit --
> we very often rely on u-boot to set up the usb hardware and if it
> doesn't the kernel hangs trying to access it.  Sometimes you just need a
> "usb start" in u-boot before launching the kernel or ubldr.  Or maybe
> there are some more fixes in 11 that haven't been merged back to 10 yet.

The u-boot's are the same for both of my tests, so unless ubldr is
doing this, it must be something in 11.

> As to the 1ghz stuff, it was my understanding that the patches make
> u-boot set the clock faster.  It would probably be better to just have
> our kernel code do that, but I haven't had time to look at the patches
> and see how much work is involved.

I looked at the patches and didn't see where it's changing the clock.

However, it does appear to be changing the clock.  Without the patch,
I see the following:

am335x_prcm0: Clocks: System 24.0 MHz, CPU 550 MHz


With the patch, I see this:

am335x_prcm0: Clocks: System 24.0 MHz, CPU 1000 MHz


So it appears to be running at almost 2x the speed (and the caches
appear to be enabled).  Cool!!!

-W.