[PATCH 5/5] platform/x86: dell: dcdbas: Use read_poll_timeout_atomic() for the type 1 SMI

[Rosen Penev <rosenp@gmail.com>]

For SMI type 1, host_control_smi() polls the APM status port in a loop
that counts down TIMEOUT_USEC_SHORT_SEMA_BLOCKING iterations and relies
on each inb() taking about a microsecond. Use
read_poll_timeout_atomic() with a 1us delay instead, like the type 2
and 3 path, so the timeout is in microseconds and does not depend on
how long a port read takes. With the delay plus the port read, the
worst-case wait grows from about 10ms to about 20ms, which only matters
when the BIOS never answers.

This removes the last users of num_ticks and EXPIRED_TIMER.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/platform/x86/dell/dcdbas.c | 12 +++++-------
 drivers/platform/x86/dell/dcdbas.h |  1 -
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/platform/x86/dell/dcdbas.c b/drivers/platform/x86/dell/dcdbas.c
index af4c1d2fe497..edc210852f2d 100644
--- a/drivers/platform/x86/dell/dcdbas.c
+++ b/drivers/platform/x86/dell/dcdbas.c
@@ -394,7 +394,6 @@ static int host_control_smi(void)
 	struct apm_cmd *apm_cmd;
 	u8 *data;
 	unsigned long flags;
-	u32 num_ticks;
 	s8 cmd_status;
 	u8 index;
 
@@ -424,12 +423,11 @@ static int host_control_smi(void)
 		spin_unlock_irqrestore(&rtc_lock, flags);
 
 		/* wait a few to see if it executed */
-		num_ticks = TIMEOUT_USEC_SHORT_SEMA_BLOCKING;
-		while ((s8)inb(PCAT_APM_STATUS_PORT) == ESM_STATUS_CMD_UNSUCCESSFUL) {
-			num_ticks--;
-			if (num_ticks == EXPIRED_TIMER)
-				return -ETIME;
-		}
+		if (read_poll_timeout_atomic(inb, cmd_status,
+					     cmd_status != ESM_STATUS_CMD_UNSUCCESSFUL,
+					     1, TIMEOUT_USEC_SHORT_SEMA_BLOCKING,
+					     false, PCAT_APM_STATUS_PORT))
+			return -ETIME;
 		break;
 
 	case HC_SMITYPE_TYPE2:
diff --git a/drivers/platform/x86/dell/dcdbas.h b/drivers/platform/x86/dell/dcdbas.h
index a05d7f667586..d5ad2363dd9e 100644
--- a/drivers/platform/x86/dell/dcdbas.h
+++ b/drivers/platform/x86/dell/dcdbas.h
@@ -42,7 +42,6 @@
 #define MAX_SYSMGMT_LONGCMD_SGENTRY_NUM		(16)
 
 #define TIMEOUT_USEC_SHORT_SEMA_BLOCKING	(10000)
-#define EXPIRED_TIMER				(0)
 
 #define SMI_CMD_MAGIC				(0x534D4931)
 #define SMM_EPS_SIG				"$SCB"
-- 
2.56.0