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Paul Burton authored
The generic MIPS implementations of halting, powering down or restarting the system all hang using a busy loop as a last resort. We have many platforms which avoid this loop by implementing their own, many using some variation upon executing a wait instruction to lower CPU power usage if we reach this point. In order to prepare for cleaning up these various custom implementations of the same thing, this patch makes the generic machine_halt(), machine_power_off() & machine_restart() functions each make use of the wait instruction to lower CPU power usage in cases where we know that the wait instruction is available. If wait isn't known to be supported then we fall back to calling cpu_wait(), and if we don't have a cpu_wait() callback then we effectively continue using a busy loop. In effect the new machine_hang() function provides a superset of the functionality that the various platforms currently provide differing subsets of. Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17178/Signed-off-by: James Hogan <jhogan@kernel.org>
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