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chromeec: Fix google_chromeec_status_check timeout

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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>
This commit is contained in:
Rob Barnes 2021-03-24 12:25:26 -06:00 committed by Patrick Georgi
parent f3e82459a8
commit 51c4d9fbfd
1 changed files with 13 additions and 16 deletions
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29
src/ec/google/chromeec/ec_lpc.c
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@ -7,6 +7,7 @@
#include <device/pnp.h> #include <device/pnp.h>
#include <ec/google/common/mec.h> #include <ec/google/common/mec.h>
#include <stdint.h> #include <stdint.h>
#include <timer.h>
#include "chip.h" #include "chip.h"
#include "ec.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) static int google_chromeec_status_check(u16 port, u8 mask, u8 cond)
{ {
u8 ec_status = read_byte(port); struct stopwatch timeout_sw;
u32 time_count = 0; /* 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);
* One second is more than plenty for any EC operation to complete do {
* (and the bus accessing/code execution) overhead will make the if ((read_byte(port) & mask) == cond)
* timeout even longer. return 0;
*/ udelay(ec_status_read_period_us);
#define MAX_EC_TIMEOUT_US 1000000 } while (!stopwatch_expired(&timeout_sw));
return -1;
while ((ec_status & mask) != cond) {
udelay(1);
if (time_count++ == MAX_EC_TIMEOUT_US)
return -1;
ec_status = read_byte(port);
}
return 0;
} }
static int google_chromeec_wait_ready(u16 port) static int google_chromeec_wait_ready(u16 port)