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Sansа Clip Zip - Improve battery life

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saratoga:
I removed most of the voltage changes, except for the one that scales voltage during CPU frequency change.  I changed this to 1.1 and 1.2v to be conservative.   I'll see if I can do a battery bench. 

Edit:  Device hard locked after 1 song. 

Mihail Zenkov:
Better test CVDD1 for boost and normal mode separately. I force one mode in set_cpu_frequency, do test for stability and then check another mode.

saratoga:
Going into the debug menu and manually boosting hard locks the player, so I suppose that is the problem. 

Edit:  1 time hard locked, the next corrupted the display, and the third worked correctly but crashed shortly there after when I tried to play a song. 

Maybe a better approach would be to confirm that frequency scaling is really working, and then try to adjust PCLK? I think 120MHz is probably far outside of the device spec. 

Mihail Zenkov:
AFAIK we don't have datasheet for this chip, so we don't know maximum frequency for it.  But you right better try set FCLK lower, maybe 180/90MHz? 

saratoga:

--- Quote from: Mihail Zenkov on October 05, 2014, 03:49:55 PM ---AFAIK we don't have datasheet for this chip, so we don't know maximum frequency for it.  But you right better try set FCLK lower, maybe 180/90MHz?

--- End quote ---

We have a datasheet for the AMSv1, which is pretty close (although the CPU core and memory amounts are different).  That one was limited to 60MHz. 

I don't think a lower FCLK will help.  My guess is that 120MHz isn't entirely stable on my player, and that there are some race conditions or other glitches when switching the F or P clocks.  Years ago we actually disabled frequency scaling because it caused a lot of random crashes. 

Edit:  Unfortunately the tracker is down so I can't check fs#11297, but as I recall, funman added quite a lot of additional code to the frequency switching functions to try and make them more stable.  Perhaps something there is needed?

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