[PATCH] spi: Reduce kthread priority

[Peter Zijlstra]

The SPI thingies request FIFO-99 by default, reduce this to FIFO-50.

FIFO-99 is the very highest priority available to SCHED_FIFO and
it not a suitable default; it would indicate the SPI work is the
most important work on the machine.

Cc: Benson Leung <bleung@xxxxxxxxxxxx>
Cc: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
Cc: Guenter Roeck <groeck@xxxxxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: linux-spi@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20190801111541.917256884@xxxxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
 drivers/platform/chrome/cros_ec_spi.c | 2 +-
 drivers/spi/spi.c                     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_spi.c b/drivers/platform/chrome/cros_ec_spi.c
index 006a8ff64057..714306bc3f79 100644
--- a/drivers/platform/chrome/cros_ec_spi.c
+++ b/drivers/platform/chrome/cros_ec_spi.c
@@ -706,7 +706,7 @@ static int cros_ec_spi_devm_high_pri_alloc(struct device *dev,
 					   struct cros_ec_spi *ec_spi)
 {
 	struct sched_param sched_priority = {
-		.sched_priority = MAX_RT_PRIO - 1,
+		.sched_priority = MAX_RT_PRIO / 2,
 	};
 	int err;
 
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 9fd7926e80c0..8e83c9567353 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1434,7 +1434,7 @@ static void spi_pump_messages(struct kthread_work *work)
  */
 static void spi_set_thread_rt(struct spi_controller *ctlr)
 {
-	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
+	struct sched_param param = { .sched_priority = MAX_RT_PRIO / 2 };
 
 	dev_info(&ctlr->dev,
 		"will run message pump with realtime priority\n");
-- 
2.20.1