Will Deacon 130cd0ecfa FROMGIT: tick/broadcast: Prefer per-cpu oneshot wakeup timers to broadcast ...

Some SoCs have two per-cpu timer implementations where the timer with the
higher rating stops in deep idle (i.e. suffers from CLOCK_EVT_FEAT_C3STOP)
but is otherwise preferable to the timer with the lower rating. In such a
design, selecting the higher rated devices relies on a global broadcast
timer and IPIs to wake up from deep idle states.

To avoid the reliance on a global broadcast timer and also to reduce the
overhead associated with the IPI wakeups, extend
tick_install_broadcast_device() to manage per-cpu wakeup timers separately
from the broadcast device.

For now, these timers remain unused.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210524221818.15850-4-will@kernel.org
(cherry picked from commit c94a8537df12 tip/tip.git timers/core)
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 185092876
Change-Id: I2d2b1bc6333d004846270d3e58dec0dca89a89d1

2021-06-04 18:33:43 +01:00

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