diff --git a/tinygrad/runtime/support/amd.py b/tinygrad/runtime/support/amd.py
index 9086d1c176..7863ad9d25 100644
--- a/tinygrad/runtime/support/amd.py
+++ b/tinygrad/runtime/support/amd.py
@@ -1,7 +1,7 @@
 import functools, importlib, time
 from collections import defaultdict
 from dataclasses import dataclass
-from tinygrad.helpers import getbits, round_up
+from tinygrad.helpers import getbits, round_up, getenv
 from tinygrad.runtime.autogen import pci
 from tinygrad.runtime.support.usb import ASM24Controller
 
@@ -33,8 +33,10 @@ def import_module(name:str, version:tuple[int, ...], version_prefix:str=""):
   raise ImportError(f"Failed to load autogen module for {name.upper()} {'.'.join(map(str, version))}")
 
 def setup_pci_bars(usb:ASM24Controller, gpu_bus:int, mem_base:int, pref_mem_base:int) -> dict[int, tuple[int, int]]:
-  try: usb.pcie_cfg_req(pci.PCI_VENDOR_ID, bus=gpu_bus, dev=0, fn=0, size=2)
-  except RuntimeError:
+  try: need_reset = (usb.pcie_cfg_req(pci.PCI_VENDOR_ID, bus=gpu_bus, dev=0, fn=0, size=2) != 0x1002)
+  except RuntimeError: need_reset = True
+
+  if need_reset or getenv("USB_RESCAN_BUS", 0) == 1:
     for bus in range(gpu_bus):
       usb.pcie_cfg_req(pci.PCI_SUBORDINATE_BUS, bus=bus, dev=0, fn=0, value=gpu_bus, size=1)
       usb.pcie_cfg_req(pci.PCI_SECONDARY_BUS, bus=bus, dev=0, fn=0, value=bus+1, size=1)