From a10d50983f7befe85acf95ea7dbf6ba9187c2d70 Mon Sep 17 00:00:00 2001
From: Jelle van der Waa <jvanderwaa@redhat.com>
Date: Wed, 19 Oct 2022 21:47:51 +0200
Subject: [PATCH] platform/x86: thinkpad_acpi: Fix reporting a non present second fan on some models
Git-commit: a10d50983f7befe85acf95ea7dbf6ba9187c2d70
Patch-mainline: v6.1-rc3
References: bsc#1210050

thinkpad_acpi was reporting 2 fans on a ThinkPad T14s gen 1, even though
the laptop has only 1 fan.

The second, not present fan always reads 65535 (-1 in 16 bit signed),
ignore fans which report 65535 to avoid reporting the non present fan.

Signed-off-by: Jelle van der Waa <jvanderwaa@redhat.com>
Link: https://lore.kernel.org/r/20221019194751.5392-1-jvanderwaa@redhat.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/platform/x86/thinkpad_acpi.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -257,6 +257,9 @@ enum tpacpi_hkey_event_t {
 
 #define onoff(status, bit) ((status) & (1 << (bit)) ? "on" : "off")
 #define enabled(status, bit) ((status) & (1 << (bit)) ? "enabled" : "disabled")
+
+#define FAN_NOT_PRESENT		65535
+
 #define strlencmp(a, b) (strncmp((a), (b), strlen(b)))
 
 
@@ -8874,7 +8877,7 @@ static int __init fan_init(struct ibm_in
 			/* Try and probe the 2nd fan */
 			tp_features.second_fan = 1; /* needed for get_speed to work */
 			res = fan2_get_speed(&speed);
-			if (res >= 0) {
+			if (res >= 0 && speed != FAN_NOT_PRESENT) {
 				/* It responded - so let's assume it's there */
 				tp_features.second_fan = 1;
 				tp_features.second_fan_ctl = 1;