[PATCH] powerpc/opal: Wake up kopald polling thread before waiting for events
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2016-07-04 04:51:50
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
On some environments (prototype machines, some simulators, etc...) there is no functional interrupt source to signal completion, so we rely on the fairly slow OPAL heartbeat. In a number of cases, the calls complete very quickly or even immediately. We've observed that it helps a lot to wakeup the OPAL heartbeat thread before waiting for event in those cases, it will call OPAL immediately to collect completions for anything that finished fast enough. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- arch/powerpc/include/asm/opal.h | 2 ++ arch/powerpc/platforms/powernv/opal-async.c | 5 +++++ arch/powerpc/platforms/powernv/opal.c | 12 ++++++++++-- 3 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 6135816..0c76bc0 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h@@ -277,6 +277,8 @@ extern int opal_error_code(int rc); ssize_t opal_msglog_copy(char *to, loff_t pos, size_t count); +void opal_wake_poller(void); + #endif /* __ASSEMBLY__ */ #endif /* _ASM_POWERPC_OPAL_H */
diff --git a/arch/powerpc/platforms/powernv/opal-async.c b/arch/powerpc/platforms/powernv/opal-async.c
index bdc8c0c..83bebee 100644
--- a/arch/powerpc/platforms/powernv/opal-async.c
+++ b/arch/powerpc/platforms/powernv/opal-async.c@@ -117,6 +117,11 @@ int opal_async_wait_response(uint64_t token, struct opal_msg *msg) return -EINVAL; } + /* Wakeup the poller before we wait for events to speed things + * up on platforms or simulators where the interrupts aren't + * functional. + */ + opal_wake_poller(); wait_event(opal_async_wait, test_bit(token, opal_async_complete_map)); memcpy(msg, &opal_async_responses[token], sizeof(*msg));
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 802f3b7..7f13302 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c@@ -55,6 +55,7 @@ struct device_node *opal_node; static DEFINE_SPINLOCK(opal_write_lock); static struct atomic_notifier_head opal_msg_notifier_head[OPAL_MSG_TYPE_MAX]; static uint32_t opal_heartbeat; +static struct task_struct *kopald_tsk; void opal_configure_cores(void) {
@@ -650,6 +651,7 @@ static void opal_i2c_create_devs(void) static int kopald(void *unused) { + unsigned long timeout = msecs_to_jiffies(opal_heartbeat) + 1; __be64 events; set_freezable();
@@ -657,12 +659,18 @@ static int kopald(void *unused) try_to_freeze(); opal_poll_events(&events); opal_handle_events(be64_to_cpu(events)); - msleep_interruptible(opal_heartbeat); + schedule_timeout_interruptible(timeout); } while (!kthread_should_stop()); return 0; } +void opal_wake_poller(void) +{ + if (kopald_tsk) + wake_up_process(kopald_tsk); +} + static void opal_init_heartbeat(void) { /* Old firwmware, we assume the HVC heartbeat is sufficient */
@@ -671,7 +679,7 @@ static void opal_init_heartbeat(void) opal_heartbeat = 0; if (opal_heartbeat) - kthread_run(kopald, NULL, "kopald"); + kopald_tsk = kthread_run(kopald, NULL, "kopald"); } static int __init opal_init(void)