diff --git a/piker/ui/_chart.py b/piker/ui/_chart.py
index 095d11e0..fb3fc388 100644
--- a/piker/ui/_chart.py
+++ b/piker/ui/_chart.py
@@ -1305,43 +1305,6 @@ class ChartPlotWidget(pg.PlotWidget):
         self.sig_mouse_leave.emit(self)
         self.scene().leaveEvent(ev)
 
-    def maxmin(
-        self,
-        name: str | None = None,
-        bars_range: tuple[
-            int, int, int, int, int, int
-        ] | None = None,
-
-    ) -> tuple[float, float]:
-        '''
-        Return the max and min y-data values "in view".
-
-        If ``bars_range`` is provided use that range.
-
-        '''
-        # TODO: here we should instead look up the ``Viz.shm.array``
-        # and read directly from shm to avoid copying to memory first
-        # and then reading it again here.
-        viz_key = name or self.name
-        viz = self._vizs.get(viz_key)
-        if viz is None:
-            log.error(f"viz {viz_key} doesn't exist in chart {self.name} !?")
-            return 0, 0
-
-        res = viz.maxmin()
-
-        if (
-            res is None
-        ):
-            mxmn = 0, 0
-            if not self._on_screen:
-                self.default_view(do_ds=False)
-                self._on_screen = True
-        else:
-            x_range, read_slc, mxmn = res
-
-        return mxmn
-
     def get_viz(
         self,
         key: str,
diff --git a/piker/ui/_display.py b/piker/ui/_display.py
index dbde38f7..d7400e4b 100644
--- a/piker/ui/_display.py
+++ b/piker/ui/_display.py
@@ -21,7 +21,6 @@ this module ties together quote and computational (fsp) streams with
 graphics update methods via our custom ``pyqtgraph`` charting api.
 
 '''
-from functools import partial
 import itertools
 from math import floor
 import time
@@ -389,7 +388,6 @@ async def graphics_update_loop(
             'fqsn': fqsn,
             'godwidget': godwidget,
             'quotes': {},
-            # 'maxmin': maxmin,
 
             'flume': flume,
 
@@ -1397,10 +1395,6 @@ async def display_symbol_data(
                 # for zoom-interaction purposes.
                 hist_viz.draw_last(array_key=fqsn)
 
-                hist_pi.vb.maxmin = partial(
-                    hist_chart.maxmin,
-                    name=fqsn,
-                )
                 # TODO: we need a better API to do this..
                 # specially store ref to shm for lookup in display loop
                 # since only a placeholder of `None` is entered in
@@ -1426,10 +1420,6 @@ async def display_symbol_data(
                     color=bg_chart_color,
                     last_step_color=bg_last_bar_color,
                 )
-                rt_pi.vb.maxmin = partial(
-                    rt_chart.maxmin,
-                    name=fqsn,
-                )
 
                 # TODO: we need a better API to do this..
                 # specially store ref to shm for lookup in display loop