From 108a9640abfada2599b6cb08c7cc00a4eebf8f8f Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Tue, 23 Oct 2012 01:39:08 -0400 Subject: [PATCH] ARM: bL_switcher: synchronize the outbound with the inbound Let's wait for the inbound CPU to come up and snoop some of the outbound CPU cache before bringing the outbound CPU down. That should be more efficient than going down right away. Possible improvements might involve some monitoring of the CCI event counters. Signed-off-by: Nicolas Pitre --- arch/arm/common/bL_switcher.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c index 34316be404d5..aab7c1274885 100644 --- a/arch/arm/common/bL_switcher.c +++ b/arch/arm/common/bL_switcher.c @@ -55,9 +55,10 @@ static int read_mpidr(void) * bL switcher core code. */ -static void bL_do_switch(void *_unused) +static void bL_do_switch(void *_arg) { unsigned ib_mpidr, ib_cpu, ib_cluster; + long volatile handshake, **handshake_ptr = _arg; pr_debug("%s\n", __func__); @@ -65,6 +66,13 @@ static void bL_do_switch(void *_unused) ib_cpu = MPIDR_AFFINITY_LEVEL(ib_mpidr, 0); ib_cluster = MPIDR_AFFINITY_LEVEL(ib_mpidr, 1); + /* Advertise our handshake location */ + if (handshake_ptr) { + handshake = 0; + *handshake_ptr = &handshake; + } else + handshake = -1; + /* * Our state has been saved at this point. Let's release our * inbound CPU. @@ -83,6 +91,14 @@ static void bL_do_switch(void *_unused) * we have none. */ + /* + * Let's wait until our inbound is alive. + */ + while (!handshake) { + wfe(); + smp_mb(); + } + /* Let's put ourself down. */ mcpm_cpu_power_down(); @@ -130,6 +146,7 @@ static int bL_switch_to(unsigned int new_cluster_id) unsigned int ob_mpidr, ob_cpu, ob_cluster, ib_mpidr, ib_cpu, ib_cluster; struct tick_device *tdev; enum clock_event_mode tdev_mode; + long volatile *handshake_ptr; int ret; this_cpu = smp_processor_id(); @@ -198,7 +215,7 @@ static int bL_switch_to(unsigned int new_cluster_id) cpu_logical_map(that_cpu) = ob_mpidr; /* Let's do the actual CPU switch. */ - ret = cpu_suspend(0, bL_switchpoint); + ret = cpu_suspend((unsigned long)&handshake_ptr, bL_switchpoint); if (ret > 0) panic("%s: cpu_suspend() returned %d\n", __func__, ret); @@ -220,6 +237,9 @@ static int bL_switch_to(unsigned int new_cluster_id) local_fiq_enable(); local_irq_enable(); + *handshake_ptr = 1; + dsb_sev(); + if (ret) pr_err("%s exiting with error %d\n", __func__, ret); return ret; -- 2.39.2