From 51c4d9fbfd9611978627ce6111b1083379a4b829 Mon Sep 17 00:00:00 2001
From: Rob Barnes <robbarnes@google.com>
Date: Wed, 24 Mar 2021 12:25:26 -0600
Subject: chromeec: Fix google_chromeec_status_check timeout
Rewrite google_chromeec_status_check to use stopwatch instead of a
delay in a while loop. In practice the while loop ends up taking
much longer than one second to timeout. Using stopwatch library will
accurately timeout after one second.
BUG=b:183524609
TEST=Build and run on guybrush
BRANCH=None
Change-Id: I363ff7453bcf81581884f92797629a6f96d42580
Signed-off-by: Rob Barnes <robbarnes@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51775
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
---
src/ec/google/chromeec/ec_lpc.c | 31 ++++++++++++++-----------------
1 file changed, 14 insertions(+), 17 deletions(-)
(limited to 'src')
diff --git a/src/ec/google/chromeec/ec_lpc.c b/src/ec/google/chromeec/ec_lpc.c
index b9c972834b..3b2a7465a3 100644
--- a/src/ec/google/chromeec/ec_lpc.c
+++ b/src/ec/google/chromeec/ec_lpc.c
@@ -7,6 +7,7 @@
#include <device/pnp.h>
#include <ec/google/common/mec.h>
#include <stdint.h>
+#include <timer.h>
#include "chip.h"
#include "ec.h"
@@ -92,23 +93,19 @@ static inline u8 write_byte(u8 val, u16 port)
static int google_chromeec_status_check(u16 port, u8 mask, u8 cond)
{
- u8 ec_status = read_byte(port);
- u32 time_count = 0;
-
- /*
- * One second is more than plenty for any EC operation to complete
- * (and the bus accessing/code execution) overhead will make the
- * timeout even longer.
- */
-#define MAX_EC_TIMEOUT_US 1000000
-
- while ((ec_status & mask) != cond) {
- udelay(1);
- if (time_count++ == MAX_EC_TIMEOUT_US)
- return -1;
- ec_status = read_byte(port);
- }
- return 0;
+ struct stopwatch timeout_sw;
+ /* One second is more than plenty for any EC operation to complete */
+ const uint64_t ec_status_timeout_us = 1 * USECS_PER_SEC;
+ /* Wait 1 usec between read attempts */
+ const uint64_t ec_status_read_period_us = 1;
+
+ stopwatch_init_usecs_expire(&timeout_sw, ec_status_timeout_us);
+ do {
+ if ((read_byte(port) & mask) == cond)
+ return 0;
+ udelay(ec_status_read_period_us);
+ } while (!stopwatch_expired(&timeout_sw));
+ return -1;
}
static int google_chromeec_wait_ready(u16 port)
--
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