On Mon, 2016-07-04 at 14:51 +1000, Benjamin Herrenschmidt wrote:
> 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 <b...@kernel.crashing.org>
Without this using drivers/mtd/devices/powernv_flash.c on mambo is
impossible. Feels like it's at least 1000x faster.
Acked-By: Michael Neuling <mi...@neuling.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)
>
>
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
