Hi,
Am 20.09.2016 um 22:57 schrieb Tony Lindgren tony@atomide.com:
Hi,
- Roy Gillotti gillottir@gmail.com [160919 09:14]:
What Kernel are you using? I've upgraded to the letux 4.8 RC5 via aTc's repo update and noticed this behavior with my bench supply capable of delivering 4A.
Sorry for the delay in responding. I'm just using typically either current mainline Linux or current Linux next.
5V power supply, two copies of dd=if/dev/urandom of=/dev/null running, hangs within a minute with temperatures below 68C. The power is actually 4.5V in this case.
Seems to confirm that the 5V issue is mainly because of the combination of supply cable resistance and high load.
With higher supply voltage the real voltage is higher and not that critical.
Just before hang I might get this on omap5-uevm:
hub 1-2:1.0: over-current condition
Interesting!
12V power supply, two copies of dd=if/dev/urandom of=/dev/null running, does not hang even with temperatures over 90C.
Also did a test with a bench power supply set to 5V. Two copies of dd=if/dev/urandom of=/dev/null running and it is stable. Lowering it to about 4.6V during the test makes it hang.
Then I also booted with a bench power supply set to 4.8V, started two copies of dd=if/dev/urandom of=/dev/null, and the blue LEDs near the power jack get dimmer and got "hub 1-2:1.0: over-current condition". This time it did not hang and after killing one of the dd processes stays running. Curiously after one hub over-current message two copies of dd kept running just fine at v4.8V.. Until I did rmmod ehci-omap as I'm using an initramfs.
Finally tried 4.8V, rmmod ehci-omap in initramfs, two copies of dd=if/dev/urandom of=/dev/null, and it seems to be running OK.
So yeah I must have moved my omap5-uevm from 12V to 5V rack shelf and that's why I started noticing hangs. And it seems something on the *hci bus is sucking power quite a bit, maybe the Ethernet?
AFAIK, Ethernet is connected through HSIC3 to the LAN9730. And the USB ports are on HSIC2 for an USB3503.
Since the Ethernet chip should not be able to report any over-current condition, I think the USB3503 is reporting this.
Both are powered by 3V3 from U3 (another TPS54426PWPR). So this SMPS is independent of the Palmas SMPS. AFAIR, these chips are specified to work for 4.5V and above. So a DC_IN dropping below 4.5V might send hickups to the 3V3 supply which mangle up EHCI.
The USB3503 has an OCS_N input connected to the 5V rail. I don't know where the threshold is where it thinks there is an over current... Maybe if this line drops below 4.5V?
BR, Nikolaus
PS: Pyra has no Ethernet and HSIC3 is unused. It has the USB3503 on HSIC2, but this is powered from VSYS and uses the internal 3V3 LDO.