examples: gpio: Replace get_time_now() with steady_clock::now()

The gpio example would continously call get_time_now() to time a loop.
There is no need to query a device here, so we query the system timer
instead.

This fixes an issue where the large amounts of control traffic could
slow down TX, causing the TX and FDX tests to fail. This was only ever
seen on the X300_HG over 1GigE.

1 files changed, 17 insertions, 12 deletions

diff --git a/host/examples/gpio.cpp b/host/examples/gpio.cpp
index ccb5eb54e..fdd65349e 100644
--- a/host/examples/gpio.cpp
+++ b/host/examples/gpio.cpp
@@ -274,9 +274,9 @@ int UHD_SAFE_MAIN(int argc, char* argv[])
     uhd::tx_metadata_t tx_md;
     tx_md.has_time_spec  = false;
     tx_md.start_of_burst = true;
-    uhd::time_spec_t stop_time;
     double timeout = 0.01;
-    uhd::time_spec_t dwell_time(dwell);
+    auto dwell_time      = std::chrono::milliseconds(static_cast<int64_t>(dwell * 1000));
+
     int loop = 0;
     uint32_t rb, expected;
 
@@ -309,8 +309,9 @@ int UHD_SAFE_MAIN(int argc, char* argv[])
 
         if (vm.count("bitbang")) {
             // dwell and continuously read back GPIO values
-            stop_time = usrp->get_time_now() + dwell_time;
-            while (not stop_signal_called and usrp->get_time_now() < stop_time) {
+            auto stop_time = std::chrono::steady_clock::now() + dwell_time;
+            while (
+                not stop_signal_called and std::chrono::steady_clock::now() < stop_time) {
                 rb = usrp->get_gpio_attr(gpio, "READBACK");
                 std::cout << "\rREADBACK: " << to_bit_string(rb, num_bits);
                 std::this_thread::sleep_for(std::chrono::milliseconds(10));
@@ -321,8 +322,9 @@ int UHD_SAFE_MAIN(int argc, char* argv[])
             std::cout << "\nTesting user controlled GPIO and ATR idle output..."
                       << std::flush;
             usrp->set_gpio_attr(gpio, "OUT", GPIO_BIT(4), GPIO_BIT(4));
-            stop_time = usrp->get_time_now() + dwell_time;
-            while (not stop_signal_called and usrp->get_time_now() < stop_time) {
+            auto stop_time = std::chrono::steady_clock::now() + dwell_time;
+            while (
+                not stop_signal_called and std::chrono::steady_clock::now() < stop_time) {
                 std::this_thread::sleep_for(std::chrono::milliseconds(100));
             }
             rb       = usrp->get_gpio_attr(gpio, "READBACK");
@@ -346,8 +348,9 @@ int UHD_SAFE_MAIN(int argc, char* argv[])
             std::cout << "\nTesting ATR RX output..." << std::flush;
             rx_cmd.stream_mode = uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS;
             rx_stream->issue_stream_cmd(rx_cmd);
-            stop_time = usrp->get_time_now() + dwell_time;
-            while (not stop_signal_called and usrp->get_time_now() < stop_time) {
+            stop_time = std::chrono::steady_clock::now() + dwell_time;
+            while (
+                not stop_signal_called and std::chrono::steady_clock::now() < stop_time) {
                 try {
                     rx_stream->recv(rx_buffs, nsamps_per_buff, rx_md, timeout);
                 } catch (...) {
@@ -374,10 +377,11 @@ int UHD_SAFE_MAIN(int argc, char* argv[])
 
             // test ATR TX by transmitting for 1 second
             std::cout << "\nTesting ATR TX output..." << std::flush;
-            stop_time            = usrp->get_time_now() + dwell_time;
+            stop_time            = std::chrono::steady_clock::now() + dwell_time;
             tx_md.start_of_burst = true;
             tx_md.end_of_burst   = false;
-            while (not stop_signal_called and usrp->get_time_now() < stop_time) {
+            while (
+                not stop_signal_called and std::chrono::steady_clock::now() < stop_time) {
                 try {
                     tx_stream->send(tx_buffs, nsamps_per_buff, tx_md, timeout);
                     tx_md.start_of_burst = false;
@@ -408,8 +412,9 @@ int UHD_SAFE_MAIN(int argc, char* argv[])
             rx_stream->issue_stream_cmd(rx_cmd);
             tx_md.start_of_burst = true;
             tx_md.end_of_burst   = false;
-            stop_time            = usrp->get_time_now() + dwell_time;
-            while (not stop_signal_called and usrp->get_time_now() < stop_time) {
+            stop_time            = std::chrono::steady_clock::now() + dwell_time;
+            while (
+                not stop_signal_called and std::chrono::steady_clock::now() < stop_time) {
                 try {
                     tx_stream->send(tx_buffs, nsamps_per_buff, tx_md, timeout);
                     tx_md.start_of_burst = false;