Sansа Clip Zip - Improve battery life

[saratoga]

Benchmarking average clock speed needed for realtime playback:

Vorbis 128k stock:  49.81 MHz
Above patch:  20.93 MHz.

So yes, it would appear to have massively increased the memory subsystem performance.  I will do more testing.

[saratoga]

Unfortunately, my player has only a 50% chance of booting with that patch applied, and most of the menus will freeze the player (although interestingly test_codec seems to be able to benchmark ok, perhaps because it forces boost or keeps the playback hardware off?). 

[Mihail Zenkov]

Can you try increase CVDD1?

[saratoga]

I'm testing that right now, < 1.0 volts may not be safe.  This is an older 130 nm chip. 

[Mihail Zenkov]

I use for test two player, both manufactured 9 months ago.

[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]

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?

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?

[Mihail Zenkov]

Sorry, I mean change PLLA and have FCLK 180 / PCLK 90.

[saratoga]

Maybe just seeing if FLCK switching from 240 to 24 at constant PCLK works would be best?

[Mihail Zenkov]

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?

My patch V3 based on this code, but it not totally stable as was mention in tracker.

[Mihail Zenkov]

Maybe just seeing if FLCK switching from 240 to 24 at constant PCLK works would be best?

We can't set PLCK constant, datasheet say we should switch PLCK to master clock, but we can't do this in AMSv2.

[saratoga]

Maybe just seeing if FLCK switching from 240 to 24 at constant PCLK works would be best?

We can't set PLCK constant, datasheet say we should switch PLCK to master clock, but we can't do this in AMSv2.

Didn't funman's old code set the PCLK to 24MHz and just change the multiplier?