ARM: 6053/1: AT91: Save power by disabling the processor clock when CPU is idle
authorAnders Larsen <al@alarsen.net>
Tue, 13 Apr 2010 11:05:32 +0000 (12:05 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Sun, 2 May 2010 22:13:13 +0000 (23:13 +0100)
Disable the processor clock when the CPU is idle.

This saves much more power than merely entering 'Wait for Interrupt' mode.
Since JTAG-debugging doesn't work when the processor clock is switched off,
make it conditional on CONFIG_DEBUG_KERNEL.

Signed-off-by: Anders Larsen <al@alarsen.net>
Acked-by: Andrew Victor <avictor.za@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
arch/arm/mach-at91/include/mach/system.h

index 5268af3933c259d22c2c1ec35d63c133b8fb5456..c80e090b36708706671d8c66ff1a67a1c0106d61 100644 (file)
 #include <mach/hardware.h>
 #include <mach/at91_st.h>
 #include <mach/at91_dbgu.h>
+#include <mach/at91_pmc.h>
 
 static inline void arch_idle(void)
 {
+#ifndef CONFIG_DEBUG_KERNEL
        /*
         * Disable the processor clock.  The processor will be automatically
         * re-enabled by an interrupt or by a reset.
         */
-//     at91_sys_write(AT91_PMC_SCDR, AT91_PMC_PCK);
-
+       at91_sys_write(AT91_PMC_SCDR, AT91_PMC_PCK);
+#else
        /*
         * Set the processor (CP15) into 'Wait for Interrupt' mode.
         * Unlike disabling the processor clock via the PMC (above)
         *  this allows the processor to be woken via JTAG.
         */
        cpu_do_idle();
+#endif
 }
 
 void (*at91_arch_reset)(void);