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MIPS 20Kc and WAIT instruction

Subject: MIPS 20Kc and WAIT instruction
From: Aurelien Jarno <>
Date: Mon, 11 Jun 2007 11:54:07 +0200
Original-recipient: rfc822;
User-agent: IceDove (X11/20070329)
Hi all,

The latest kernels from or do not enter low
power mode when the CPU is idle on a MIPS 20Kc CPU.

Looking at the code in arch/mips/kernel/cpu-probe.c, the "case"
corresponding to the 20Kc CPU is commented out:

        case CPU_5KC:
/*      case CPU_20KC:*/
        case CPU_24K:

According to the datasheet this CPU supports the WAIT instruction, so I
don't really understand why it is disabled in the kernel. Does anybody
know why?


  .''`.  Aurelien Jarno             | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'         |
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