b200: Fixed setting of max rate

DSP rates are now being tracked as in whether or not they've been set.
We can disregard unset DSPs for the automatic clock rate calculation.

Reviewed-By: Derek Kozel <derek.kozel@ettus.com>

1 files changed, 9 insertions, 10 deletions

diff --git a/host/lib/usrp/b200/b200_io_impl.cpp b/host/lib/usrp/b200/b200_io_impl.cpp
index 93f5b22fc..ec37f2f6f 100644
--- a/host/lib/usrp/b200/b200_io_impl.cpp
+++ b/host/lib/usrp/b200/b200_io_impl.cpp
@@ -82,9 +82,9 @@ void b200_impl::set_auto_tick_rate(
         num_chans = std::max(size_t(1), max_chan_count());
     }
     const double max_tick_rate = ad9361_device_t::AD9361_MAX_CLOCK_RATE/num_chans;
+    using namespace uhd::math;
     if (rate != 0.0 and
-        (uhd::math::fp_compare::fp_compare_delta<double>(rate, uhd::math::FREQ_COMPARISON_DELTA_HZ) >
-         uhd::math::fp_compare::fp_compare_delta<double>(max_tick_rate, uhd::math::FREQ_COMPARISON_DELTA_HZ))) {
+        (fp_compare::fp_compare_delta<double>(rate, FREQ_COMPARISON_DELTA_HZ) > max_tick_rate)) {
         throw uhd::value_error(str(
                 boost::format("Requested sampling rate (%.2f Msps) exceeds maximum tick rate of %.2f MHz.")
                 % (rate / 1e6) % (max_tick_rate / 1e6)
@@ -96,26 +96,25 @@ void b200_impl::set_auto_tick_rate(
     boost::uint32_t lcm_rate = (rate == 0) ? 1 : static_cast<boost::uint32_t>(floor(rate + 0.5));
     for (int i = 0; i < 2; i++) { // Loop through rx and tx
         std::string dir = (i == 0) ? "tx" : "rx";
-        // We have no way of knowing which DSPs are used, so we check them all.
+        // We assume all 'set' DSPs are being used.
         BOOST_FOREACH(const std::string &dsp_no, _tree->list(str(boost::format("/mboards/0/%s_dsps") % dir))) {
             fs_path dsp_path = str(boost::format("/mboards/0/%s_dsps/%s") % dir % dsp_no);
             if (dsp_path == tree_dsp_path) {
                 continue;
             }
+            if (not _tree->access<bool>(dsp_path / "rate/set").get()) {
+                continue;
+            }
             double this_dsp_rate = _tree->access<double>(dsp_path / "rate/value").get();
             // Check if the user selected something completely unreasonable:
-            if (uhd::math::fp_compare::fp_compare_delta<double>(this_dsp_rate, uhd::math::FREQ_COMPARISON_DELTA_HZ) >
-                uhd::math::fp_compare::fp_compare_delta<double>(max_tick_rate, uhd::math::FREQ_COMPARISON_DELTA_HZ)) {
+            if (fp_compare::fp_compare_delta<double>(this_dsp_rate, FREQ_COMPARISON_DELTA_HZ) > max_tick_rate) {
                 throw uhd::value_error(str(
                         boost::format("Requested sampling rate (%.2f Msps) exceeds maximum tick rate of %.2f MHz.")
                         % (this_dsp_rate / 1e6) % (max_tick_rate / 1e6)
                 ));
             }
-            // If this_dsp_rate == 0.0, the sampling rate for this DSP hasn't been set, so
-            // we don't take that into consideration.
-            if (this_dsp_rate == 0.0) {
-                continue;
-            }
+            // Clean up floating point rounding errors if they crept in
+            this_dsp_rate = std::min(max_tick_rate, this_dsp_rate);
             lcm_rate = boost::math::lcm<boost::uint32_t>(
                     lcm_rate,
                     static_cast<boost::uint32_t>(floor(this_dsp_rate + 0.5))