From 0dc18f9623ea722352bcc276265a5049f16b7e09 Mon Sep 17 00:00:00 2001
From: Pavel Kirienko <pavel.kirienko@gmail.com>
Date: Mon, 1 Jun 2015 16:45:12 +0300
Subject: [PATCH] Fixed STM32 NuttX driver

---
 .../driver/include/uavcan_stm32/thread.hpp    |  5 +--
 .../stm32/driver/src/uc_stm32_thread.cpp      | 31 +++++++------------
 2 files changed, 14 insertions(+), 22 deletions(-)

diff --git a/libuavcan_drivers/stm32/driver/include/uavcan_stm32/thread.hpp b/libuavcan_drivers/stm32/driver/include/uavcan_stm32/thread.hpp
index d2c6869ddc..1ad2d30716 100644
--- a/libuavcan_drivers/stm32/driver/include/uavcan_stm32/thread.hpp
+++ b/libuavcan_drivers/stm32/driver/include/uavcan_stm32/thread.hpp
@@ -58,6 +58,9 @@ public:
 
 #elif UAVCAN_STM32_NUTTX
 
+/**
+ * All bus events are reported as POLLIN.
+ */
 class BusEvent : uavcan::Noncopyable
 {
     static const unsigned MaxPollWaiters = 8;
@@ -75,8 +78,6 @@ class BusEvent : uavcan::Noncopyable
     int close(::file* filp);
     int poll(::file* filp, ::pollfd* fds, bool setup);
 
-    unsigned makePollMask() const;
-
     int addPollWaiter(::pollfd* fds);
     int removePollWaiter(::pollfd* fds);
 
diff --git a/libuavcan_drivers/stm32/driver/src/uc_stm32_thread.cpp b/libuavcan_drivers/stm32/driver/src/uc_stm32_thread.cpp
index c24885968d..88fd0b37ed 100644
--- a/libuavcan_drivers/stm32/driver/src/uc_stm32_thread.cpp
+++ b/libuavcan_drivers/stm32/driver/src/uc_stm32_thread.cpp
@@ -99,7 +99,13 @@ int BusEvent::poll(::file* filp, ::pollfd* fds, bool setup)
         ret = addPollWaiter(fds);
         if (ret == 0)
         {
-            fds->revents |= fds->events & makePollMask();
+            /*
+             * Two events can be reported via POLLIN:
+             *  - The RX queue is not empty. This event is level-triggered.
+             *  - Transmission complete. This event is edge-triggered.
+             * FIXME Since TX event is edge-triggered, it can be lost between poll() calls.
+             */
+            fds->revents |= fds->events & ((can_driver_.makeSelectMasks().read == 0) ? 0 : POLLIN);
             if (fds->revents != 0)
             {
                 (void)sem_post(fds->sem);
@@ -114,26 +120,11 @@ int BusEvent::poll(::file* filp, ::pollfd* fds, bool setup)
     return ret;
 }
 
-unsigned BusEvent::makePollMask() const
-{
-    const uavcan::CanSelectMasks select_masks = can_driver_.makeSelectMasks();
-    unsigned poll_mask = 0;
-    if (select_masks.read != 0)
-    {
-        poll_mask |= POLLIN;
-    }
-    if (select_masks.write != 0)
-    {
-        poll_mask |= POLLOUT;
-    }
-    return poll_mask;
-}
-
 int BusEvent::addPollWaiter(::pollfd* fds)
 {
     for (unsigned i = 0; i < MaxPollWaiters; i++)
     {
-        if (pollset_[i] == nullptr)
+        if (pollset_[i] == NULL)
         {
             pollset_[i] = fds;
             return 0;
@@ -148,7 +139,7 @@ int BusEvent::removePollWaiter(::pollfd* fds)
     {
         if (fds == pollset_[i])
         {
-            pollset_[i] = nullptr;
+            pollset_[i] = NULL;
             return 0;
         }
     }
@@ -201,9 +192,9 @@ void BusEvent::signalFromInterrupt()
     for (unsigned i = 0; i < MaxPollWaiters; i++)
     {
         ::pollfd* const fd = pollset_[i];
-        if (fd != nullptr)
+        if (fd != NULL)
         {
-            fd->revents = fd->events & makePollMask();
+            fd->revents |= fd->events & POLLIN;
             if ((fd->revents != 0) && (fd->sem->semcount <= 0))
             {
                 (void)sem_post(fd->sem);