pasemi: Distribute interrupts evenly across cpus
PATCH 1/1 pasemi: Distribute interrupts evenly across cpus
[POWERPC] pasemi: Distribute interrupts evenly across cpus
By default the OpenPIC on PWRficient will bias to one core (since that will improve changes of the other core being able to stay idle/powered down). However, this conflicts with most irq load balancing schemes, since setting an interrupt to be delivered to either core doesn't really result in the load being shared. It also doesn't work well with the soft irq disable feature of PPC, since EE will stay on until the first interrupt is taken while soft disabled, but the PIC doesn't know that when choosing the target.
There's a conf0 bit to specify that deliveries should be evenly spread (round robin) between the cores. Running in that mode makes more sense for Linux.
arch/powerpc/platforms/pasemi/setup.c +1 -1
@@ -224,7 +224,7 @@ static __init void pas_init_IRQ(void) openpic_addr =of_read_number (opprop, naddr);printk (KERN_DEBUG "OpenPIC addr: %lx\n" , openpic_addr); - mpic_flags =MPIC_PRIMARY |MPIC_LARGE_VECTORS ; + mpic_flags =MPIC_PRIMARY |MPIC_LARGE_VECTORS |MPIC_NO_BIAS ; nmiprop =of_get_property (mpic_node,"nmi-source" ,NULL );if (nmiprop)
arch/powerpc/sysdev/mpic.c +5 -0
@@ -1279,6 +1279,11 @@ void __init mpic_init(struct mpic *mpic)mpic_read (mpic->gregs,MPIC_INFO (GREG_GLOBAL_CONF_0 )) | MPIC_GREG_GCONF_8259_PTHROU_DIS); +if (mpic->flags &MPIC_NO_BIAS ) +mpic_write (mpic->gregs,MPIC_INFO (GREG_GLOBAL_CONF_0 ), +mpic_read (mpic->gregs,MPIC_INFO (GREG_GLOBAL_CONF_0 )) + |MPIC_GREG_GCONF_NO_BIAS ); +/* Set current processor priority to 0 */ mpic_cpu_write (MPIC_INFO (CPU_CURRENT_TASK_PRI ),0 );
include/asm-powerpc/mpic.h +3 -0
@@ -22,6 +22,7 @@#define MPIC_GREG_GLOBAL_CONF_0 0x00020#define MPIC_GREG_GCONF_RESET 0x80000000#define MPIC_GREG_GCONF_8259_PTHROU_DIS 0x20000000 +#define MPIC_GREG_GCONF_NO_BIAS 0x10000000#define MPIC_GREG_GCONF_BASE_MASK 0x000fffff#define MPIC_GREG_GCONF_MCK 0x08000000#define MPIC_GREG_GLOBAL_CONF_1 0x00030
@@ -350,6 +351,8 @@ struct mpic#define MPIC_LARGE_VECTORS 0x00000100/* Enable delivery of prio 15 interrupts as MCK instead of EE */ #define MPIC_ENABLE_MCK 0x00000200 +/* Disable bias among target selection, spread interrupts evenly */ +#define MPIC_NO_BIAS 0x00000400/* MPIC HW modification ID */ #define MPIC_REGSET_MASK 0xf0000000