From 26989b5e7c85ac1d5715a5ef2667335061920e96 Mon Sep 17 00:00:00 2001
From: Lei YU <mine260309@gmail.com>
Date: Thu, 23 Nov 2017 16:14:51 +0800
Subject: [PATCH] sysfs: Return -ETIMEDOUT instead of throw exception

Aspeed fan tach gives ETIMEDOUT error when host is powered off, it
causes phosphor-hwmon exit with read failure exception.
Make it return -ETIMEDOUT so that it gives negative value for fan speed
as workaround.

Signed-off-by: Lei YU <mine260309@gmail.com>
---
 sysfs.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sysfs.cpp b/sysfs.cpp
index 369d2e7..f390de6 100644
--- a/sysfs.cpp
+++ b/sysfs.cpp
@@ -308,6 +308,12 @@ uint32_t HwmonIO::read(
                 throw std::system_error(rc, std::generic_category());
             }
 
+            if (rc == ETIMEDOUT)
+            {
+                // Workaround for AST fan tach driver
+                // that returns -ETIMEDOUT when fan is not runnings
+                return -rc;
+            }
             --retries;
             std::this_thread::sleep_for(delay);
             continue;
-- 
1.9.1