[PATCH 2/8] Input: serio - add fast reconnect option

Dmitry Torokhov
2017-03-09T22:18:48Z

Devices connected to serio bus are quite slow, and to improve apparent
speed of resume process, serio core resumes (reconnects) its devices
asynchronously, by posting port reconnect requests to a workqueue.
Unfortunately this means that if there is a dependent device of a given
serio port (for example SMBus part of touchpad connected via both PS/2 and
SMBus), we do not have a good way of ensuring resume order.

This change allows drivers to define "fast reconnect" handlers that would
be called in-line during system resume. Drivers need to ensure that these
handlers are truly "fast".

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
drivers/input/serio/serio.c | 22 +++++++++++++++++-----
include/linux/serio.h | 1 +
2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
index 1ca7f551e2da..34793ce2df91 100644
--- a/drivers/input/serio/serio.c
+++ b/drivers/input/serio/serio.c
@@ -953,12 +953,24 @@ static int serio_suspend(struct device *dev)
static int serio_resume(struct device *dev)
{
struct serio *serio = to_serio_port(dev);
+ int error = -ENOENT;

- /*
- * Driver reconnect can take a while, so better let kseriod
- * deal with it.
- */
- serio_queue_event(serio, NULL, SERIO_RECONNECT_PORT);
+ mutex_lock(&serio->drv_mutex);
+ if (serio->drv && serio->drv->fast_reconnect) {
+ error = serio->drv->fast_reconnect(serio);
+ if (error && error != -ENOENT)
+ dev_warn(dev, "fast reconnect failed with error %d\n",
+ error);
+ }
+ mutex_unlock(&serio->drv_mutex);
+
+ if (error) {
+ /*
+ * Driver reconnect can take a while, so better let
+ * kseriod deal with it.
+ */
+ serio_queue_event(serio, NULL, SERIO_RECONNECT_PORT);
+ }

return 0;
}
diff --git a/include/linux/serio.h b/include/linux/serio.h
index c733cff44e18..138a5efe863a 100644
--- a/include/linux/serio.h
+++ b/include/linux/serio.h
@@ -77,6 +77,7 @@ struct serio_driver {
irqreturn_t (*interrupt)(struct serio *, unsigned char, unsigned int);
int (*connect)(struct serio *, struct serio_driver *drv);
int (*reconnect)(struct serio *);
+ int (*fast_reconnect)(struct serio *);
void (*disconnect)(struct serio *);
void (*cleanup)(struct serio *);

--
2.12.0.246.ga2ecc84866-goog