From 285d7483aa3323c90891e26b73a0c9d9cc5f53e4 Mon Sep 17 00:00:00 2001
From: Stefan Wahren <stefan.wahren@i2se.com>
Date: Thu, 11 Apr 2019 15:30:10 +0200
Subject: [PATCH] Documentation: pwm-fan: Add description for RPM support

This adds a short description for the new RPM support of the pwm-fan
driver.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 Documentation/hwmon/pwm-fan | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/hwmon/pwm-fan b/Documentation/hwmon/pwm-fan
index 18529d2e3bcfa..82fe96742feea 100644
--- a/Documentation/hwmon/pwm-fan
+++ b/Documentation/hwmon/pwm-fan
@@ -15,3 +15,6 @@ The driver implements a simple interface for driving a fan connected to
 a PWM output. It uses the generic PWM interface, thus it can be used with
 a range of SoCs. The driver exposes the fan to the user space through
 the hwmon's sysfs interface.
+
+The fan rotation speed returned via the optional 'fan1_input' is extrapolated
+from the sampled interrupts from the tachometer signal within 1 second.
-- 
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