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HID: Only dump input if someone is listening

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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 <rydberg@euromail.se>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Henrik Rydberg 2012-09-01 21:47:11 +02:00 committed by Jiri Kosina
parent 67ddbb3e65
commit 9bfc8da00b
1 changed files with 2 additions and 1 deletions
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3
drivers/hid/hid-core.c
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@ -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);