From 44c9728a60095e82e010f0c2943a29cee3931a14 Mon Sep 17 00:00:00 2001
From: Xiang Xiao <xiaoxiang@xiaomi.com>
Date: Fri, 9 Nov 2018 08:08:18 -0600
Subject: [PATCH] rivers/rwbuffer.c:  Don't queue work to flush write buffer if
 CONFIG_DRVR_WRDELAY == 0

---
 drivers/rwbuffer.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/rwbuffer.c b/drivers/rwbuffer.c
index 576f7bf875..47fff94e07 100644
--- a/drivers/rwbuffer.c
+++ b/drivers/rwbuffer.c
@@ -63,14 +63,14 @@
 
 /* Configuration ************************************************************/
 
-#ifndef CONFIG_SCHED_WORKQUEUE
-#  error "Worker thread support is required (CONFIG_SCHED_WORKQUEUE)"
-#endif
-
 #ifndef CONFIG_DRVR_WRDELAY
 #  define CONFIG_DRVR_WRDELAY 350
 #endif
 
+#if !defined(CONFIG_SCHED_WORKQUEUE) && CONFIG_DRVR_WRDELAY != 0
+#  error "Worker thread support is required (CONFIG_SCHED_WORKQUEUE)"
+#endif
+
 /****************************************************************************
  * Private Types
  ****************************************************************************/
@@ -195,7 +195,7 @@ static void rwb_wrflush(struct rwbuffer_s *rwb)
  * Name: rwb_wrtimeout
  ****************************************************************************/
 
-#ifdef CONFIG_DRVR_WRITEBUFFER
+#if defined(CONFIG_DRVR_WRITEBUFFER) && CONFIG_DRVR_WRDELAY != 0
 static void rwb_wrtimeout(FAR void *arg)
 {
   /* The following assumes that the size of a pointer is 4-bytes or less */
@@ -221,12 +221,14 @@ static void rwb_wrtimeout(FAR void *arg)
 #ifdef CONFIG_DRVR_WRITEBUFFER
 static void rwb_wrstarttimeout(FAR struct rwbuffer_s *rwb)
 {
+#if CONFIG_DRVR_WRDELAY != 0
   /* CONFIG_DRVR_WRDELAY provides the delay period in milliseconds. CLK_TCK
    * provides the clock tick of the system (frequency in Hz).
    */
 
-  int ticks = (CONFIG_DRVR_WRDELAY + CLK_TCK/2) / CLK_TCK;
+  int ticks = MSEC2TICK(CONFIG_DRVR_WRDELAY);
   (void)work_queue(LPWORK, &rwb->work, rwb_wrtimeout, (FAR void *)rwb, ticks);
+#endif
 }
 #endif
 
@@ -237,7 +239,9 @@ static void rwb_wrstarttimeout(FAR struct rwbuffer_s *rwb)
 #ifdef CONFIG_DRVR_WRITEBUFFER
 static inline void rwb_wrcanceltimeout(struct rwbuffer_s *rwb)
 {
+#if CONFIG_DRVR_WRDELAY != 0
   (void)work_cancel(LPWORK, &rwb->work);
+#endif
 }
 #endif