[Letux-kernel] 1.5GHz problems

Grazvydas Ignotas notasas at gmail.com
Tue Aug 2 01:42:22 CEST 2016


On Mon, Aug 1, 2016 at 12:37 AM, H. Nikolaus Schaller <hns at goldelico.com> wrote:
>
> B) Pyra: LEDs seem to be blinking slightly irregular @500 MHz only boot (may be harmless)
> Sometimes the serial console appears to show delays (looks as if some IRQ blocking process runs a little slow?)
>
> C) 5432EVM (letux-4.7.0 w/o Pyra Mainboard connected)
> I have modified the DT so that it also has 500 / 750 / 1250 MHz OPPs like for the Pyra.
> Termperature measurements (with cooling fingers installed)

500 was removed by TI, I guess there was some reason for that. 750 and
1250 were fabricated by you, not from some TI data, right? For uEVM
stability testing I'd remove the "unofficial" frequencies, there could
be some problems we don't know about, and uEVM has been always rock
stable with the defaults (1 and 1.5 GHz only) for me.

> And it might be that we have too much noise on VDD_MPU @1.5GHz.
> This is now a test scenario that I can compare to the EVM as soon as I find time for doing that.

Looking forward to that, I hope it will give some hints.

> Anyways these results now need some interpretation. Especially why VSSYS goes down
> from 3.6V to 3.5V! And the other voltages remain the same. This either means that the
> Palmas draws even more current from VSYS - or the bq24297 has reset itself to the default
> 3.5V regulation mode. Or something else?

But 3.5V is still in spec, right?
Maybe it would it be possible to mod the board to feed VSYS from some
strong lab supply?


Gražvydas


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