Am Fri, 12 Oct 2018 06:15:15 -0700 hat Tony Lindgren tony@atomide.com geschrieben:
Hi.
Do you know if disabling self-refresh has any negative side effects? Would it increase power consumption a lot or probably not really noticeable?
It will increase the idle power consumption quite a bit AFAIK, this is a sign of something being broken for sure.
Well, hardware- or softwarewise broken? Or can't be made out yet.
The only thing that helps besides DLL disable is disabling self-refresh. I think the RAMs are incompatible with how OMAP5 does power saving, that's all there is to it. We'll have to choose one of those workarounds. Probably disabling self-refresh makes the most sense since unlike the DLL option it's not against any specs or requirements.
These are my findings as well, I was not able to find anything that would make things better or worse regarding the self refresh issue other than disable self refresh or disable internal dll like Grazvydas listed. Timing value changes for tRFC and tXSDLL don't seem to make a difference.
Damn.
My gut feeling is it's some kind of signaling issue occasionally causing the relocking the of the ddr internal dll to fail. The only difference compared to other omap5 and dra7 devices is the use of two chip selects on Pyra 4GB.
Hm, though we've used the IBIS files to simulate everything - and the current CPU boards passed, so hardware-wise, it SHOULD be okay.
And what's even weirder: The more is going on, the more noise you have in the normal signals, but that doesn't seem to affect the RAM. What could be bad enough to affect the relocking of the DDR internal DLL?
Are there differences between switching to / from self-refreshing to normal state on dual-die RAM chips which maybe isn't properly included in the kernel or similar?
Hm... does the IGEP use dual-die RAM chips?
But for developer devices and testing, yeah disabling memory self-refresh is the way to go.
Yes, it helps so I can work on the tester script.
However, it's the last issue preventing me to give the "Go" for mass production.
So the question is, how to solve that.