[Skiboot] [v2 PATCH 3/4] p8i2c: Use calculated poll_interval when booting OPAL

[Stewart Smith]

Otherwise we'd default to 2seconds (TIMER_POLL) during boot on
chips with a functional i2c interrupt, leading to slow i2c
during boot (or hitting timeouts instead).

Signed-off-by: Stewart Smith <stewart at linux.vnet.ibm.com>
--
change in v2: don't set poll_interval = 0 when no children (this would hit
an assert on booting on garrison, possibly others)
---
 hw/p8-i2c.c       | 23 +++++++++++++----------
 include/skiboot.h |  5 +++++
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/hw/p8-i2c.c b/hw/p8-i2c.c
index 12a4d1aabfeb..faaf6ede3373 100644
--- a/hw/p8-i2c.c
+++ b/hw/p8-i2c.c
@@ -870,7 +870,7 @@ static int p8_i2c_start_request(struct p8_i2c_master *master,
 	struct p8_i2c_master_port *port;
 	struct p8_i2c_request *request =
 		container_of(req, struct p8_i2c_request, req);
-	uint64_t cmd, now;
+	uint64_t cmd, now, poll_interval;
 	int64_t rc, tbytes;
 
 	DBG("Starting req %d len=%d addr=%02x (offset=%x)\n",
@@ -975,7 +975,11 @@ static int p8_i2c_start_request(struct p8_i2c_master *master,
 	/* Run a poll timer for boot cases or non-working interrupts
 	 * cases
 	 */
-	now = schedule_timer(&master->poller, master->poll_interval);
+	if (!opal_booting() && master->irq_ok)
+		poll_interval = TIMER_POLL;
+	else
+		poll_interval = master->poll_interval;
+	now = schedule_timer(&master->poller, poll_interval);
 
 	/* Calculate and start timeout */
 	if (request->timeout) {
@@ -1428,15 +1432,14 @@ static void p8_i2c_init_one(struct dt_node *i2cm, enum p8_i2c_master_type type)
 		port++;
 	}
 
-	/* If we have no interrupt, calculate a poll interval,
-	 * otherwise just use a TIMER_POLL timer which will tick
-	 * on OPAL pollers only (which allows us to operate
-	 * during boot before interrupts are functional etc...
+	/* When at runtime and we have the i2c irq, we just use it
+	 * (see p8_i2c_start_request), but in the situation where
+	 * one of those isn't the case (e.g. during boot), we need
+	 * a better poll interval to efficiently crank the i2c machine.
+	 * poll_interval is that interval.
 	 */
-	if (master->irq_ok)
-		master->poll_interval = TIMER_POLL;
-	else
-		master->poll_interval = p8_i2c_get_poll_interval(max_bus_speed);
+	master->poll_interval = (max_bus_speed) ? p8_i2c_get_poll_interval(max_bus_speed) : TIMER_POLL;
+
 	master->byte_timeout = master->irq_ok ?
 		msecs_to_tb(I2C_TIMEOUT_IRQ_MS) :
 		msecs_to_tb(I2C_TIMEOUT_POLL_MS);
diff --git a/include/skiboot.h b/include/skiboot.h
index 97bdce784eaf..3f7c077812ed 100644
--- a/include/skiboot.h
+++ b/include/skiboot.h
@@ -86,6 +86,11 @@ struct debug_descriptor {
 };
 extern struct debug_descriptor debug_descriptor;
 
+static inline bool opal_booting(void)
+{
+	return !(debug_descriptor.state_flags & OPAL_BOOT_COMPLETE);
+}
+
 /* Console logging */
 #define PR_EMERG	0
 #define PR_ALERT	1
-- 
2.1.4