From bf9c9866112e468699a17eb2128f4c8d59f503e8 Mon Sep 17 00:00:00 2001 From: Gabe Black Date: Mon, 24 Oct 2011 21:54:27 -0700 Subject: Use finer grain udelays while waitng for the i8042 keyboard buffer to empty On x86, the i8042 keyboard controller driver frequently waits for the keyboard input buffer to be empty to make sure the controller has had a chance to process the data it was given. The way the delay loop was structured, if the controller hadn't cleared the corresponding status bit immediately, it would wait 1ms before checking again. If the keyboard responded quickly but not instantly, the driver would still wait a full 1ms when perhaps 1us would have been sufficient. Because udelay is a busy wait anyway, this change decreases the delay between checks to 1us. Also, this change gets rid of a hardcoded 250ms delay. On Stumpy, this saves 100-150ms during boot. Also, the total boot time I'm measuring at ToT is a little higher than expected. I'd like to see what other people measure. BUG=chrome-os-partner:6585 TEST=Built and booted on Stumpy. Built and booted on Alex, and verified that the keyboard still worked at the u-boot prompt. Change-Id: Ic361c4e88ded8e57b4377790dd011a11a0ce385b Signed-off-by: Gabe Black Reviewed-on: http://gerrit.chromium.org/gerrit/10623 Commit-Ready: Gabe Black Tested-by: Gabe Black Reviewed-by: Gabe Black --- drivers/input/i8042.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'drivers') diff --git a/drivers/input/i8042.c b/drivers/input/i8042.c index 3bdfa7d7f6..8575d78d13 100644 --- a/drivers/input/i8042.c +++ b/drivers/input/i8042.c @@ -633,11 +633,10 @@ static void kbd_led_set (void) static int kbd_input_empty (void) { - int kbdTimeout = KBD_TIMEOUT; + int kbdTimeout = KBD_TIMEOUT * 1000; - /* wait for input buf empty */ while ((in8 (I8042_STATUS_REG) & 0x02) && kbdTimeout--) - udelay(1000); + udelay(1); return kbdTimeout != -1; } @@ -651,8 +650,6 @@ static int kbd_reset (void) out8 (I8042_DATA_REG, 0xff); - udelay(250000); - if (kbd_input_empty() == 0) return -1; -- cgit v1.2.3