[POWERPC] hvc_console: Polling mode timer backoff
[POWERPC] hvc_console: Polling mode timer backoff

Add a back-off mechanism to hvc_console's polling logic.   This change
drops the timers/second ratio from ~90 to ~1/2 while the console is
idle.
This change is most noticeable when watching /proc/timer_stats output.

This only affects when the hvc_console is running in poll mode, i.e.
power4 and cell systems.

I've tested on Power4, Michael Ellerman has both contributed to the
patch and tested on cell.

Signed-off-by: Will Schmidt <546b2fc3167f5ef85ad1f3e892b259e5904f9bf6@vnet.ibm.com>
Signed-off-by: Michael Ellerman <17b9e1c64588c7fa6419b4d29dc1f4426279ba01@ellerman.id.au>
Acked-by: Linas Vepstas <ba5b7161287ad232d67ab9ebf53b27130547a421@austin.ibm.com>
Signed-off-by: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas