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Linux L138: Entering Deep Sleep Mode Using Software Handshaking

Filippo Ferrara
Prodigy 140 points

Other Parts Discussed in Thread: OMAP-L138

Hi all,

Does anybody knows if the patch for entering into Deep Sleep Mode using Software Handshaking (as explained in the chapter 10.10.4 of sprugm7e.pdf) exists and it is already available somewhere?

If I've understood correctly that's the only solution if I want to trigger the enter to Deep Sleep Mode by an external event (pin),I mean whithout Software Handshaking I couldn't prepare my sistem (calling registered drivers etc...) I jusr would switch immediatly to deep sleep status, is that correct?

Thank you

  • 0
    TI__Expert 6385 points

    Hi Filipo,

    Current Linux software only enables support for RTC based wake-up from DeepSleep0. The software handshaking mode requires an external wake controller not present on the EVM so has not been implemented/tested in TI's Linux offering.

    If you have an external wake controller on your board, you would have to modify the DeepSleep code to take care of it. Looking at the TRM, nDEEPSLEEPsignal has no effect till SLEEPENABLE bit is set by software. Current Linux implementation sets this bit at the very end of the DeepSleep sequence (see arch/arm/mach-davinci/sleep.S in Linux kernel sources), after all drivers have been suspended. This bit should be used to acheive synchronization between OMAP-L138 and the external wake controller.

    Thanks,

    Sekhar