Hi,
Am 14.11.2016 um 04:06 schrieb Michael Mrozek EvilDragon@openpandora.org:
Am Sat, 12 Nov 2016 00:52:02 +0200 hat Grazvydas Ignotas notasas@gmail.com geschrieben:
Okay, here are some more, very interesting test results I just made!
You can grab all the board files I created here: http://openpandora.org/downloads/testing/?C=M;O=D
And the results are attached.
Now, what's interesting?
Mainly two things:
- Single vs multiple defined speeds
If I only define a SINGLE speed, I could only get up to 1,18GHz. From 1,19 GHz it gets unstable and with 1,20 GHz it always freezes.
When defining a LOT of speeds, it runs better! For example, with this:
500000 850000 750000 950000 1000000 1060000 1100000 1100000 1150000 1150000 1170000 1170000 1190000 1190000 1200000 1200000 1220000 1220000 1250000 1250000I can run up to 1,25GHz without any issues. It didn't crash in high-load running for multiple minutes. The voltage used at 1,25GHz wasn't set any higher than with the lower speeds that crashed for me.
Interesting!
Why did this run stable? Because the voltage wasn't increased from 1,06V to 1,25V at once but in smaller steps? That could mean our capacitors aren't able to buffer peaks as good as they should.
Unfortunately, I couldn't get it to run it stable at higher speeds with that trick though, so at some time it simply seems our power supply is not stable enough anymore.
- Voltages
I'm not 100% sure the voltages work as they should. While it does seem have SOME effect (feels a bit more stable sometimes), it doesn't really seem like it's 100% working.
For example, if I set the voltage to 0,75V (less than the OMAPs allowed minimum), it still runs stable at 1,15GHz. Same with 0,85V at 1GHz.
I expected it to crash right away, with such a low voltage setting for that high frequencies.
So that makes me wonder: Could it be there's some bug somewhere in our board file that leads to a bug where the voltage is not properly applied?
Is there some easy way to check what voltage it really runs?
I think it is possible to look into the Palmas registers through I2C and check how they are set up.
http://git.goldelico.com/?p=gta04-kernel.git;a=blob;f=Letux/root/palmas-dump...
I will try to add the max. power consumption peaks for some of the interesting values within the next few days.
Another idea I had: Can ANY voltage be defined in the board file?
The palmas manual states that 0.5V - 1.65V can be programmed in 0.01V steps. Device tree specifies a bit narrower range of 0.6 - 1.5V, just to be safe I guess.
The OMAP manual says the allowed range is 0.85V - 1.25V. "The voltage at the device ball should never be below the MIN voltage or above the MAX voltage for any amount of time. This requirement includes dynamic voltage events such as AC ripple, voltage transients, voltage dips, etc."
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?
I don't think so. I think Nikolaus said he has measured the voltage to be really changing, I guess he could confirm that again just in case...
Gražvydas
-- Mit freundlichen Grüßen,
Michael Mrozek
OpenPandora GmbH Geschäftsführer: Michael Mrozek
Schäffbräustr. 11 85049 Ingolstadt Deutschland Tel.: 0841 / 990 5548 http://www.openpandora.de/ HRB 4879, Amtsgericht Ingolstadt
eMail: mrozek@openpandora.org <Results.pdf>