plot_utils: fix plot_allfreqs() for one actor

When the system has only one actor and you use trappy.summary_plots() or
trappy.compare_runs() you get:

    Traceback (most recent call last):
      File "trappy/tests/test_trappy.py", line 127, in test_summary_plots_one_actor
        trappy.summary_plots(self.actor_order, map_label)
      File "trappy/trappy/compare_runs.py", line 96, in summary_plots
        return compare_runs(actor_order, map_label, [(title, path)], **kwords)
      File "trappy/trappy/compare_runs.py", line 78, in compare_runs
        trappy.plot_utils.plot_allfreqs(run_data, map_label, **kwords)
      File "trappy/trappy/plot_utils.py", line 209, in plot_allfreqs
        run.plot_allfreqs(map_label, ax=ax)
      File "trappy/trappy/ftrace.py", line 531, in plot_allfreqs
        for this_ax, (label, dfr) in zip(ax, all_freqs):
    TypeError: zip argument #1 must support iteration

This is because plt.subplots() returns just the axis if ncols and nrows
are both 1, a 1D array if either ncols or nrows is 1 and a 2D array
otherwise.  plot_utils.plot_all_freqs() copes with ncols being 1 but not
with nrows being 1.  The latter happens when you use summary_plots() or
compare_runs() and there is only one actor.

Fix it so that axis is always a 2D array: the first index is the run and
the second the actor.

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/test_trappy.py b/tests/test_trappy.py
index 53e0afe..d66b96d 100644
--- a/tests/test_trappy.py
+++ b/tests/test_trappy.py
@@ -107,6 +107,25 @@ class TestTrappy(BaseTestThermal):
         trappy.summary_plots(self.actor_order, self.map_label)
         matplotlib.pyplot.close('all')
 
+    def test_summary_plots_one_actor(self):
+        """summary_plots() works if there is only one actor"""
+
+        # Strip out devfreq and little traces
+        trace_out = ""
+        with open("trace.txt") as fin:
+            for line in fin:
+                if ("thermal_power_devfreq_get_power:" not in line) and \
+                   ("thermal_power_devfreq_limit:" not in line) and \
+                   ("thermal_power_cpu_get_power: cpus=00000000,00000039" not in line) and \
+                   ("thermal_power_cpu_limit: cpus=00000000,00000039" not in line):
+                    trace_out += line
+
+        with open("trace.txt", "w") as fout:
+            fout.write(trace_out)
+
+        map_label = {"00000000,00000006": "A57"}
+        trappy.summary_plots(self.actor_order, map_label)
+        matplotlib.pyplot.close('all')
 
     def test_compare_runs(self):
         """Basic compare_runs() functionality"""