From cb3c368385307b23bf6597ee3c2f6bb9395ed11e Mon Sep 17 00:00:00 2001
From: Abel Briggs <abelbriggs1@hotmail.com>
Date: Sat, 14 May 2022 10:49:23 -0500
Subject: [PATCH] ec/acpi: Return error codes on timeout

The `send` and `recv` API functions currently print error messages
if a timeout occurs while polling the EC, but they perform the I/O
transaction regardless. This can put the EC in a bad state or
otherwise invoke undefined hardware behavior.

Most callers ignore the return value currently, but for callers
which do not, we should make sure our behavior is correct.

Signed-off-by: Abel Briggs <abelbriggs1@hotmail.com>
Change-Id: Ifb87dd1ac869807fd08463bd8fef36d0389b325e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64350
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
---
 src/ec/acpi/ec.c | 10 +++++-----
 src/ec/acpi/ec.h |  4 ++--
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/ec/acpi/ec.c b/src/ec/acpi/ec.c
index 7d495a1264..fbd9acda70 100644
--- a/src/ec/acpi/ec.c
+++ b/src/ec/acpi/ec.c
@@ -47,7 +47,7 @@ int send_ec_command_timeout(u8 command, int timeout_us)
 	if (!ec_ready_send(timeout_us)) {
 		printk(BIOS_DEBUG, "Timeout while sending command 0x%02x to EC!\n",
 				command);
-		// return -1;
+		return -1;
 	}
 
 	outb(command, ec_cmd_reg);
@@ -65,7 +65,7 @@ int send_ec_data_timeout(u8 data, int timeout_us)
 	if (!ec_ready_send(timeout_us)) {
 		printk(BIOS_DEBUG, "Timeout while sending data 0x%02x to EC!\n",
 				data);
-		// return -1;
+		return -1;
 	}
 
 	outb(data, ec_data_reg);
@@ -73,18 +73,18 @@ int send_ec_data_timeout(u8 data, int timeout_us)
 	return 0;
 }
 
-u8 recv_ec_data(void)
+int recv_ec_data(void)
 {
 	return recv_ec_data_timeout(EC_RECV_TIMEOUT_US);
 }
 
-u8 recv_ec_data_timeout(int timeout_us)
+int recv_ec_data_timeout(int timeout_us)
 {
 	u8 data;
 
 	if (!ec_ready_recv(timeout_us)) {
 		printk(BIOS_DEBUG, "Timeout while receiving data from EC!\n");
-		// return -1;
+		return -1;
 	}
 
 	data = inb(ec_data_reg);
diff --git a/src/ec/acpi/ec.h b/src/ec/acpi/ec.h
index 665c62f559..2c978f3aa5 100644
--- a/src/ec/acpi/ec.h
+++ b/src/ec/acpi/ec.h
@@ -29,8 +29,8 @@ int send_ec_command(u8 command);
 int send_ec_command_timeout(u8 command, int timeout);
 int send_ec_data(u8 data);
 int send_ec_data_timeout(u8 data, int timeout);
-u8 recv_ec_data(void);
-u8 recv_ec_data_timeout(int timeout);
+int recv_ec_data(void);
+int recv_ec_data_timeout(int timeout);
 void ec_clear_out_queue(void);
 u8 ec_status(void);
 u8 ec_query(void);