No deep sleep after speedtest with stock ROM/Kernel G901F

Hi, I've noticed a bug (or my phone's got a hardware problem?) with deep sleep.
I noticed that after a speedtest in LTE-A (G901F), deep sleep doesn't work anymore and CPU is always at lower freq when screen of... No problem with wifi speedtest...
Tried this :
- BOK2 stock rom : no deep sleep after speedtest
- BOL1 : no deep sleep after speedtest
- Nova Rom : no deep sleep after speedtest
- SImpleGx : no deep sleep after speedtest
- StockRom with and Without stockkernel v1.0 or 1.1 : no deep sleep after speedtest
BUT...with kernel Guyver, it works, but I loose Sview Cover...
Any idea ? Someone's got the same problem ? Maybe Samsung' kernel problem ?
Thanks for help.

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