Work around/disable power saving mode (best practice)

answered 2018-03-18 19:59:59 +0200

takimata
496 ●8 ●16 ●20

libkeepalive approach

The library is part of Sfos: https://together.jolla.com/question/175209/sudo-make-me-a-sandwich/?answer=175235#post-id-175235

sth. like:

#include <keepalive/backgroundactivity.h>

// see https://git.merproject.org/mer-core/nemo-keepalive/blob/12a1528bacd20e0a07e9bbcbc287b08641986265/lib/backgroundactivity.h
BackgroundActivity activity;

connect(&activity, SIGNAL(running()), this, SLOT(backgroundActivity()));
activity.setWakeupFrequency(BackgroundActivity::TwoAndHalfMinutes);


void backgroundActivity() {
    // background job in regular intervals, executed even if the device is not actively used
}

answered 2018-03-18 19:59:04 +0200

takimata
496 ●8 ●16 ●20

DBUS approach, e.g., execute dbus-send --system --print-reply --dest=com.nokia.mce /com/nokia/mce/request com.nokia.mce.request.set_config string:'/system/osso/dsm/display/autosuspend_policy' variant:int32:$MAGIC_NUMBER

in C++:

/** enables (-> best power saving) or disables (-> cpu active) deep suspend/sleep

 * @param deepSuspendAllowed
 */
void allowDeepSuspend(bool deepSuspendAllowed) {

    QDBusMessage msg = QDBusMessage::createMethodCall("com.nokia.mce", "/com/nokia/mce/request", "com.nokia.mce.request", "set_config");

    // set the two arguments:

    msg << "/system/osso/dsm/display/autosuspend_policy";

    // Always stay in on-mode:  SUSPEND_POLICY_DISABLED = 0
    // Normal transitions between on, early suspend, and late suspend:  SUSPEND_POLICY_ENABLED = 1
    // Allow on and early suspend, but never enter late suspend:  SUSPEND_POLICY_EARLY_ONLY = 2
    // this keeps at least one cpu core running for our application!
    // Disable suspend when charger is connected:  SUSPEND_POLICY_DISABLE_ON_CHARGER = 3
    // Note: Applies only when device is running normally in the USER mode, i.e. not in ACT_DEAD etc special modes.
    //
    // see https://git.merproject.org/mer-core/mce/blob/master/tools/mcetool.c
    // and https://git.merproject.org/mer-core/mce/blob/master/modules/display.h
    msg << QVariant::fromValue(QDBusVariant((deepSuspendAllowed ? 1 : 2)));

    // MINOR: hoping that the msg gets through, no error checking yet (but it's quite reliable, though)
    // maybe there's a dbus signal available?
    QDBusConnection::systemBus().send(msg);
}