[PATCH 5/5] platform/chrome: cros_ec_spi: Set PROBE_PREFER_ASYNCHRONOUS

Brian Norris
2022-10-28T21:15:24Z

This driver often takes on the order of 10ms to start, but in some cases
as much as 600ms [1]. It shouldn't have many cross-device dependencies
to race with, nor racy access to shared state with other drivers, so
this should be a relatively low risk change.

This driver was pinpointed as part of a survey of top slowest initcalls
(i.e., are built in, and probing synchronously) on a lab of ChromeOS
systems.

[1] 600ms was especially surprising to me, so I checked a little deeper.
This driver is used to interface with Embedded Controllers besides just
the traditional laptop power-state controller -- it also interfaces with
some fingerprint readers, which may start up in parallel with the
kernel, or which may not even be present on some SKUs, despite having a
node for it. Thus, our time is wasted just timing out talking to it. At
least we can do that without blocking everyone else.

Signed-off-by: Brian Norris <briannorris@chromium.org>
---

drivers/platform/chrome/cros_ec_spi.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/platform/chrome/cros_ec_spi.c b/drivers/platform/chrome/cros_ec_spi.c
index 7360b3ff6e4f..21143dba8970 100644
--- a/drivers/platform/chrome/cros_ec_spi.c
+++ b/drivers/platform/chrome/cros_ec_spi.c
@@ -834,6 +834,7 @@ static struct spi_driver cros_ec_driver_spi = {
.name = "cros-ec-spi",
.of_match_table = cros_ec_spi_of_match,
.pm = &cros_ec_spi_pm_ops,
+ .probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
.probe = cros_ec_spi_probe,
.remove = cros_ec_spi_remove,
--
2.38.1.273.g43a17bfeac-goog