Am Fri, 11 Nov 2016 22:54:00 +0200 hat Grazvydas Ignotas notasas@gmail.com geschrieben:
Hi,
ah, okay, so it will most probably not fix our issue.
I've done some tests with various board files. These board files and the results are attached.
Basically, 1,25GHz never worked for me, regardless the voltage setting.
Often, it simply froze at: cpufreq: cpufreq_online: CPU0: Unlisted initial frequency changed to: 1250000 KHz
Until it changes the frequency, everything worked fine (as was expected).
After that, things go haywire and I get all kinds of different crashes. I've attached a text file with some different snippets. I don't think there's much of a clue in there (as it probably just means the CPU goes crazy), but I've attached them anyways. Maybe one of you can make something out of it.
One thing that's interesting in my opinion:
It even behaves the same at 1,35V and even 1,45V! I had hoped that in case we have a voltage drop, driving it with 1,35V or 1,45V would keep the voltage high enough so that it continues to run, at least for a while.
But it doesn't!
What does that mean?
* Is the resistance so high that the drop is too much, even with WAY higher voltage? * Is not the voltage the problem, but the overall power consumption? i.e. can we provide the OMAP5 with at least 4W or is there a bottleneck?
Or something else?
Another idea I had: Can ANY voltage be defined in the board file? Or could it be that 1,35V / 1,45V is not allowed by the driver and the PALMAS sticks to the default voltage in case it has an illegal voltage?
Hi,
from a quick look at the code, it seems it's only actually used by cpufreq to make decisions when to switch frequencies (opp code only passes the value to cpufreq). For example, if the latency is large, it may make sense to wait for longer CPU usage spike before switching to higher frequency to avoid useless switching back and forth.
Gražvydas
On Fri, Nov 11, 2016 at 10:19 PM, Michael Mrozek EvilDragon@openpandora.org wrote:
Hi,
while looking at the different voltages, I found another value that spawned my interest:
clock-latency = <300000>;
Does anyone know what that value is and what it could be used for?
I found some discussion on a forum, where someone mentioned it's probably the latency between the clock source pin and the OMAP5 clock pin and therefore depends on board design and trace length.
No idea if that's true, but if yes, could that have an effect in our case?
-- Mit freundlichen Grüßen,
Michael Mrozek
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