# Raspberry Pi Brev2 and 24k ints/sec



## Juha Nurmela (Dec 5, 2015)

```
FreeBSD aspi 11.0-CURRENT FreeBSD 11.0-CURRENT #0 r291495: Tue Dec  1 08:23:29 UTC 2015  root@releng2.nyi.freebsd.org:/usr/obj/arm.armv6/usr/src/sys/RPI-B  arm
```
`systat -vm` and `vmstat -i` report a large interrupt rate, around 24'000 interrupts / second from *bcm283x_dwcotg0*. It runs fine, 0% _reported_ interrupt time, and everything looks fine as far as I can tell (sd, ethernet, audio out, usb, leds are ok). This must be normal, what's the story behind it? Sound or video generation? Can it be turned down?

I did try 10.2 just before 11.0-CURRENT and I did not spot this there.

Juha


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## Juha Nurmela (Dec 5, 2015)

Nothing to worry about, it seems:
http://lists.freebsd.org/pipermail/freebsd-arm/2015-August/012065.html


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## Phishfry (Dec 6, 2015)

So totally wrong it is the OTG usb port

```
dwcotg0: <DWC OTG 2.0 integrated USB controller>
```


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## Phishfry (Dec 7, 2015)

Funny thing is you were thinking audio hertz problem and I was thinking GPIO pin mux problem.
Somehow it is the USB device...Strange.


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## Juha Nurmela (Dec 7, 2015)

```
aspi $ vmstat -i
interrupt  total  rate
irq1: mbox0  27  0
irq2: vchiq0  3  0
irq11: systimer0  19187031  24
irq17: bcm283x_dwco  2033860852  28
irq26: bcm_dma0  779076  9
irq65: uart0  1775  0
irq70: sdhci_bcm0  104960  1
Total  2053933724  24245
```

That's a bit odd, the 24000 rate is not .... charged? to dwcotg by vmstat. Probably I just failed to spot this on 10.2.

It's nice, feels like old jeans. It has hung once though, overnight, when just sitting there. Don't know why, no screen was attached. Base utility `i2c` does not work at all, it seems to be a known discrepancy with the device and userland, but _I2CRDWR_ ioctl works and works fast, 150 kHz rate. Pumping 100 kB takes 5 seconds to go and cpu is idling.

There's no hardware clock and no `ntpstat`. I wonder what's the proper way to see if `ntpd` has stabilized. Maybe `ntpq -crv | grep sync_ntp` is enough for my coarse needs.

Juha


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## Phishfry (Dec 7, 2015)

I really have to give kudos to the developers for getting this Arm stuff going. Think how long the PC platform had to develop things like SMBus and all the other glue we take for granted. Something tells me these $40 dollar boards don't have a real good underlying structure and I have to wonder if they are worth the embedded moniker. Feel a quality circuit board and then feel a maker board. The difference is apparent. Right down to crooked connectors. The NVIDIA TK1 feels solid but it costs alot. It also has an Mini-PCIe slot, so obviously some PCIe fabric there. I don't think the other offerings have a PCIe bus.. Maker boards seem more like a learning experience than a deployment platform.


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## trev (Dec 8, 2015)

Phishfry said:


> Something tells me these $40 dollar boards don't have a real good underlying structure and I have to wonder if they are worth the embedded moniker. Feel a quality circuit board and then feel a maker board. The difference is apparent. Right down to crooked connectors.


The Raspberry Pis are hardly "maker boards" - they've been professionally and commercially produced in the millions!
I have an RPi B+ and an RPi 2 and none of the connectors are crooked.


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## Phishfry (Dec 9, 2015)

Sorry for that rant. I stand by what I said.
I am not here to bash any of them. The money you pay for them is beyond fair.
My BananaPi has crooked connectors. My Odroid feels solid. So varying quailites.


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