[PATCH v3 16/20] HID: Only dump input if someone is listening
From: Henrik Rydberg <hidden>
Date: 2012-09-01 19:43:19
Also in:
lkml
Subsystem:
hid core layer, the rest · Maintainers:
Jiri Kosina, Benjamin Tissoires, Linus Torvalds
Going through the motions of printing the debug message information takes a long time; using the keyboard can lead to a 160 us irqsoff latency. This patch skips hid_dump_input() when there are no open handles, which brings latency down to 100 us. Signed-off-by: Henrik Rydberg <redacted> --- drivers/hid/hid-core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 60ea284..5b74e78 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c@@ -996,7 +996,8 @@ static void hid_process_event(struct hid_device *hid, struct hid_field *field, struct hid_driver *hdrv = hid->driver; int ret; - hid_dump_input(hid, usage, value); + if (!list_empty(&hid->debug_list)) + hid_dump_input(hid, usage, value); if (hdrv && hdrv->event && hid_match_usage(hid, usage)) { ret = hdrv->event(hid, field, usage, value);
--
1.7.12