b200: Throw error for unreachable sampling rates

When auto tick rate is used, and the sampling rate exceeds the
limits, throw an error instead of coercing to the default rate.

1 files changed, 18 insertions, 1 deletions

diff --git a/host/lib/usrp/b200/b200_io_impl.cpp b/host/lib/usrp/b200/b200_io_impl.cpp
index eb7bbe048..52a90a623 100644
--- a/host/lib/usrp/b200/b200_io_impl.cpp
+++ b/host/lib/usrp/b200/b200_io_impl.cpp
@@ -81,6 +81,7 @@ void b200_impl::set_auto_tick_rate(
     if (num_chans == 0) { // Divine them
         num_chans = std::max(size_t(1), max_chan_count());
     }
+    const double max_tick_rate = ad9361_device_t::AD9361_MAX_CLOCK_RATE/num_chans;
 
     // See also the doxygen documentation for these steps in b200_impl.hpp
     // Step 1: Obtain LCM and max rate from all relevant dsps
@@ -94,6 +95,13 @@ void b200_impl::set_auto_tick_rate(
                 continue;
             }
             double this_dsp_rate = _tree->access<double>(dsp_path / "rate/value").get();
+            // Check if the user selected something completely unreasonable:
+            if (this_dsp_rate > 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 == B200_DEFAULT_RATE, we assume the user did not actually set
             // the sampling rate. If the user *did* set the rate to
             // B200_DEFAULT_RATE on all DSPs, then this will still work (see below).
@@ -118,7 +126,6 @@ void b200_impl::set_auto_tick_rate(
 
     // Step 2: Determine whether if we can use lcm_rate (preferred),
     // or have to give up because too large:
-    const double max_tick_rate = ad9361_device_t::AD9361_MAX_CLOCK_RATE/num_chans;
     double base_rate = static_cast<double>(lcm_rate);
     if (base_rate > max_tick_rate) {
         UHD_MSG(warning)
@@ -175,10 +182,19 @@ void b200_impl::update_tick_rate(const double new_tick_rate)
     }
 }
 
+#define CHECK_RATE_AND_THROW(rate)  \
+        if (rate >ad9361_device_t::AD9361_MAX_CLOCK_RATE ) { \
+            throw uhd::value_error(str( \
+                    boost::format("Requested sampling rate (%.2f Msps) exceeds maximum tick rate.") \
+                    % (rate / 1e6) \
+            )); \
+        }
+
 double b200_impl::coerce_rx_samp_rate(rx_dsp_core_3000::sptr ddc, size_t dspno, const double rx_rate)
 {
     // Have to set tick rate first, or the ddc will change the requested rate based on default tick rate
     if (_tree->access<bool>("/mboards/0/auto_tick_rate").get()) {
+        CHECK_RATE_AND_THROW(rx_rate);
         const std::string dsp_path = (boost::format("/mboards/0/rx_dsps/%s") % dspno).str();
         set_auto_tick_rate(rx_rate, dsp_path);
     }
@@ -208,6 +224,7 @@ double b200_impl::coerce_tx_samp_rate(tx_dsp_core_3000::sptr duc, size_t dspno,
 {
     // Have to set tick rate first, or the duc will change the requested rate based on default tick rate
     if (_tree->access<bool>("/mboards/0/auto_tick_rate").get()) {
+        CHECK_RATE_AND_THROW(tx_rate);
         const std::string dsp_path = (boost::format("/mboards/0/tx_dsps/%s") % dspno).str();
         set_auto_tick_rate(tx_rate, dsp_path);
     }