Hi,
Am 20.09.2016 um 16:29 schrieb Michael Mrozek EvilDragon@openpandora.org:
On September 20, 2016 7:45:01 AM GMT+02:00, "H. Nikolaus Schaller"
hns@goldelico.com wrote:
- When the 5V LED is on (power is below 5.6V, which means it switches
to Power Jack Input), the EVM runs unstable. At least yours, mine and aTcs, from what we know. It seems Nikolaus' one is not affected (for whatever reason).
Well, I have never tested with higher voltages.
And you never tested the whole system, just the CPU itself (without using USB, HDMI, etc. with 5V) Which is a good information as well!
No, I have had also run tests with USB and HDMI... But not recently.
Recent and current tests I have done were w/o HDMI and USB devices but the old Pyra Mainboard + a Displayboard.
Anyways my kernel hangs on the EVM are gone :(
In other words: I was not able to reproduce them so far. Even with the same 5V 2A power supply as before...
Running for hours at 200% CPU load. Or doing heavy apt-get update.
- What has the 5V switch to do with the power supply of the OMAP5?
Nothing.
That nothing seems to have a high impact regarding stability ;)
Not necessarily.
As described in earlier mails, a higher voltage of the power supply gives more safety margin if cables are weak.
And that is independent of the existence of any 5V switch.
Except one thing: if there are power sinks at the USB ports which draw high current, switching might make glitches on the DC input. But I don't see how this should affect OMAP operation.
That theory has one problem: It doesn't crash while switching. If voltage you feed the EVM with is below 5.6V, it ALWAYS runs in that special 5V mode without any switching happening.
Yes. 5V in goes only through the switch chip to 5V out.
So it seems to have something to do with that mode, not with the switching.
What's interesting though: As it runs stable for you (without using HDMI or USB), it probably doesn't have anything to do with the AC adapter breaking down because of a too high power consumption. HDMI should not use as much power as running the OMAP5 with full power for a while!
Indeed.
Unless there is a bug which makes the OMAP5 have the same power consumption regardless you stress it or not, but that's what a good power supply which shows the Ampere can answer.
This would also mean that the temperature would be constantly high... But that isn't.
And I had measured the real power demand at the sense resistors a while ago. And that heavily depends on what I am doing.
So why does simply using HDMI make the board run unstable, but only in that 5V mode?
Hm. That would mean a bug in the DSS system.
- Is that a hardware bug of the EVM or a problem with the OMAP5?
I tend to think it is an EVM specific effect. Pyra does not have this switch circuit at all.
Does that mean the Pyra always run similar to the 5V mode or rather to the more than 5.6V mode (using SMPS)
As written in some other mail, the Pyra circuit is similar to EVM running in higher than 5.6V mode. It just uses a different SMPS to get that down to 3.7V. And one that does not want to see more than ca. 5.3V at its input (USB specifications).
It is mainly an automatic bypass of the 5.6V - 12V -> 5V converter (because USB and HDMI need 5V). It is bypassed if input voltage is low enough.
Hmm, could HDMI or USB cause a freeze of the OMAP5 if the voltage is not stable enough?
I don't know how HDMI signaling works, but in theory: yes. A device that does inject invalid activities may not be properly ignored by the kernel and make it fail.
But since I am no longer finding the issues I had last week on my EVM it might simply have been a corrupt SD card. A single bad bit at the right position might have such effects.
So it is IMHO not really helpful to invest much more time in understanding the EVM because I think we can't learn much about Pyra issues.
BR, Nikolaus
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.
5.1V - Some instabilities HDMI, SATA resets and USB devices blink
out.
Sometimes freezes before getting to X.
5.2V - Boots up Consistently. random Freezes when using Firefox when attempting to watch a Youtube video. Sometime just HDMI blinks out occasionally.
5.3V - Seems stable running CPU intensive things. Firefox running youtube video, running 720p video in smplayer and quake 2 at once. highest current draw observed ~1.6A during spikes. Random Freeze occurs generally within 5 to 10 minutes of use.
5.4V - Same as 5.3V
5.5V - Same as 5.4V
5.6V - 5V LED blinks, HDMI blinks out or won’t go into a resolution above 1024x768. Can seem to use firefox, youtube videos without issues.
5.7V - 5V LED is off, but turns on when drawing ~1A. HDMI working appropriately.
5.8V - Same as 5.7V
5.9V - 5V LED is off, but turns on when drawing ~1A. oddly the 1024x768 bug appears again at this voltage. powered off a few times to confirm it.
6.0V - 5V LED is only displays as on with current draw is ~1.4A.
Seems
stable otherwise.
6.2V - 5V LED is only blinked a few times, when the current draw briefly spiked about 1.6A. seems just as stable.
6.3V - 5V LED off completely. No noticeable blinks. appears stable.
On Mon, Sep 19, 2016 at 12:06 PM, Tony Lindgren tony@atomide.com wrote:
- H. Nikolaus Schaller hns@goldelico.com [160919 02:55]:
> Am 19.09.2016 um 11:39 schrieb Grazvydas Ignotas > notasas@gmail.com: I could give it > a try on my uEVM to add another data point. FWIW my uEVM has > been always rock stable (12V supply), but I haven't updated my > kernel for a while.
Yes, would be nice to compare your results and observations.
My omap5-uevm is on a 5V power supply right now it seems, I'm pretty sure it used to have 12V supply earlier.
Regards,
Tony _______________________________________________ Kernel mailing list Kernel@pyra-handheld.com http://pyra-handheld.com/cgi-bin/mailman/listinfo/kernel
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