From 3abc16af57c9939724df92fcbda296b25cc95168 Mon Sep 17 00:00:00 2001
From: Patryk Duda <pdk@semihalf.com>
Date: Tue, 18 May 2021 16:07:58 +0200
Subject: [PATCH] platform/chrome: cros_ec_proto: Send command again when timeout occurs
Git-commit: 3abc16af57c9939724df92fcbda296b25cc95168
Patch-mainline: v5.15-rc1
References: git-fixes

Sometimes kernel is trying to probe Fingerprint MCU (FPMCU) when it
hasn't initialized SPI yet. This can happen because FPMCU is restarted
during system boot and kernel can send message in short window
eg. between sysjump to RW and SPI initialization.

Cc: <stable@vger.kernel.org> # 4.4+
Signed-off-by: Patryk Duda <pdk@semihalf.com>
Link: https://lore.kernel.org/r/20210518140758.29318-1-pdk@semihalf.com
Signed-off-by: Benson Leung <bleung@chromium.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/platform/chrome/cros_ec_proto.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index aa7f7aa77297..a7404d69b2d3 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -279,6 +279,15 @@ static int cros_ec_host_command_proto_query(struct cros_ec_device *ec_dev,
 	msg->insize = sizeof(struct ec_response_get_protocol_info);
 
 	ret = send_command(ec_dev, msg);
+	/*
+	 * Send command once again when timeout occurred.
+	 * Fingerprint MCU (FPMCU) is restarted during system boot which
+	 * introduces small window in which FPMCU won't respond for any
+	 * messages sent by kernel. There is no need to wait before next
+	 * attempt because we waited at least EC_MSG_DEADLINE_MS.
+	 */
+	if (ret == -ETIMEDOUT)
+		ret = send_command(ec_dev, msg);
 
 	if (ret < 0) {
 		dev_dbg(ec_dev->dev,
-- 
2.35.3