From 1dc8de699c94910e73901d0b392e64ea5ba2d7dc Mon Sep 17 00:00:00 2001
From: deadprogram <ron@hybridgroup.com>
Date: Wed, 20 Dec 2017 07:05:10 +0100
Subject: [PATCH] sysfs: pause briefly to allow udev rules to apply when
 exporting PWMPin

Signed-off-by: deadprogram <ron@hybridgroup.com>
---
 sysfs/pwm_pin.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sysfs/pwm_pin.go b/sysfs/pwm_pin.go
index c3d56093..5747aded 100644
--- a/sysfs/pwm_pin.go
+++ b/sysfs/pwm_pin.go
@@ -6,6 +6,7 @@ import (
 	"os"
 	"strconv"
 	"syscall"
+	"time"
 )
 
 // PWMPin is the interface for sysfs PWM interactions
@@ -65,6 +66,11 @@ func (p *PWMPin) Export() error {
 		}
 	}
 
+	// Pause to avoid race condition in case there is any udev rule
+	// that changes file permissions on newly exported PWMPin. This
+	// is a common circumstance when running as a non-root user.
+	time.Sleep(100 * time.Millisecond)
+
 	return nil
 }