ARM: 6436/1: AT91: Fix power-saving in idle-mode on 926T processors

According to Atmel, their 926T processors (AT91 post RM9200) requires
'Wait for Interrupt' mode be entered right after disabling the processor clock
in order to minimise current consumption when idle, so do both provided we're
not running on a 920T (an RM9200).

Furthermore, get rid of the #ifndef CONFIG_DEBUG_KERNEL, since arch_idle()
can be turned off completely with the kernel parameter 'nohlt'.

Cc: Andrew Victor <avictor.za@gmail.com>
Signed-off-by: Anders Larsen <al@alarsen.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mach-at91/include/mach/system.h b/arch/arm/mach-at91/include/mach/system.h
index c80e090b36708706671d8c66ff1a67a1c0106d61..ee8db152592e087c8fe986dd1c7d7e557d473ad4 100644 (file)
--- a/arch/arm/mach-at91/include/mach/system.h
+++ b/arch/arm/mach-at91/include/mach/system.h
@@ -28,17 +28,16 @@
 
 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);
-#else
+#ifndef CONFIG_CPU_ARM920T
        /*
         * 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.
+        * Post-RM9200 processors need this in conjunction with the above
+        * to save power when idle.
         */
        cpu_do_idle();
 #endif