Revert "tools/pydfu.py: Respect longer timeouts requested by DFU dev..."

This reverts commit 4d6f60d428.

This implementation used the timeout as a maximum amount of time needed for
the operation, when actually the spec and other tools suggest that it's the
minumum delay needed between subsequent USB transfers.

tools/pydfu.py

@@ -22,8 +22,6 @@ import sys
 import usb.core
 import usb.util
 import zlib
-import time
-import math
 
 # VID/PID
 __VID = 0x0483
@@ -31,8 +29,6 @@ __PID = 0xDF11
 
 # USB request __TIMEOUT
 __TIMEOUT = 4000
-__NEXT_TIMEOUT = 0
-__STATUS_TIMEOUT = 20000
 
 # DFU commands
 __DFU_DETACH = 0
@@ -99,13 +95,6 @@ else:
         return usb.util.get_string(dev, index)
 
 
-def timeout():
-    global __NEXT_TIMEOUT
-    t = max(__TIMEOUT, __NEXT_TIMEOUT)
-    __NEXT_TIMEOUT = 0
-    return int(math.ceil(t))
-
-
 def find_dfu_cfg_descr(descr):
     if len(descr) == 9 and descr[0] == 9 and descr[1] == _DFU_DESCRIPTOR_TYPE:
         nt = collections.namedtuple(
@@ -161,32 +150,17 @@ def init():
 
 def abort_request():
     """Sends an abort request."""
-    __dev.ctrl_transfer(0x21, __DFU_ABORT, 0, __DFU_INTERFACE, None, timeout())
+    __dev.ctrl_transfer(0x21, __DFU_ABORT, 0, __DFU_INTERFACE, None, __TIMEOUT)
 
 
 def clr_status():
     """Clears any error status (perhaps left over from a previous session)."""
-    __dev.ctrl_transfer(0x21, __DFU_CLRSTATUS, 0, __DFU_INTERFACE, None, timeout())
+    __dev.ctrl_transfer(0x21, __DFU_CLRSTATUS, 0, __DFU_INTERFACE, None, __TIMEOUT)
 
 
 def get_status():
     """Get the status of the last operation."""
-    _timeout = time.time() + max(__STATUS_TIMEOUT, timeout())
-    stat = None
-    while time.time() < _timeout:
-        try:
-            stat = __dev.ctrl_transfer(
-                0xA1, __DFU_GETSTATUS, 0, __DFU_INTERFACE, 6, int(_timeout - time.time())
-            )
-            break
-        except usb.core.USBError as ex:
-            # If the firmware is blocked the transfer can timeout much quicker than
-            # the supplied timeout. If so, retry until the overall timeout is used up.
-            if "Operation timed out" not in str(ex):
-                raise
-
-    if stat is None:
-        raise SystemExit("DFU: get_status timed out")
+    stat = __dev.ctrl_transfer(0xA1, __DFU_GETSTATUS, 0, __DFU_INTERFACE, 6, 20000)
 
     # firmware can provide an optional string for any error
     if stat[5]:
@@ -194,12 +168,6 @@ def get_status():
         if message:
             print(message)
 
-    # firmware can send a longer timeout request while it's performing slow operation eg. erase
-    timeout_ms = stat[1] << 16 | stat[2] << 8 | stat[3]
-    if timeout_ms:
-        global __NEXT_TIMEOUT
-        __NEXT_TIMEOUT = __TIMEOUT + timeout_ms
-
     return stat[4]
 
 
@@ -212,9 +180,9 @@ def check_status(stage, expected):
 def mass_erase():
     """Performs a MASS erase (i.e. erases the entire device)."""
     # Send DNLOAD with first byte=0x41
-    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 0, __DFU_INTERFACE, "\x41", timeout())
+    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 0, __DFU_INTERFACE, "\x41", __TIMEOUT)
 
-    # Execute erase and wait until complete
+    # Execute last command
     check_status("erase", __DFU_STATE_DFU_DOWNLOAD_BUSY)
 
     # Check command state
@@ -228,7 +196,7 @@ def page_erase(addr):
 
     # Send DNLOAD with first byte=0x41 and page address
     buf = struct.pack("<BI", 0x41, addr)
-    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 0, __DFU_INTERFACE, buf, timeout())
+    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 0, __DFU_INTERFACE, buf, __TIMEOUT)
 
     # Execute last command
     check_status("erase", __DFU_STATE_DFU_DOWNLOAD_BUSY)
@@ -241,7 +209,7 @@ def set_address(addr):
     """Sets the address for the next operation."""
     # Send DNLOAD with first byte=0x21 and page address
     buf = struct.pack("<BI", 0x21, addr)
-    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 0, __DFU_INTERFACE, buf, timeout())
+    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 0, __DFU_INTERFACE, buf, __TIMEOUT)
 
     # Execute last command
     check_status("set address", __DFU_STATE_DFU_DOWNLOAD_BUSY)
@@ -275,7 +243,7 @@ def write_memory(addr, buf, progress=None, progress_addr=0, progress_size=0):
         # Send DNLOAD with fw data
         chunk = min(__cfg_descr.wTransferSize, xfer_total - xfer_bytes)
         __dev.ctrl_transfer(
-            0x21, __DFU_DNLOAD, 2, __DFU_INTERFACE, buf[xfer_bytes : xfer_bytes + chunk], timeout()
+            0x21, __DFU_DNLOAD, 2, __DFU_INTERFACE, buf[xfer_bytes : xfer_bytes + chunk], __TIMEOUT
         )
 
         # Execute last command
@@ -299,7 +267,7 @@ def write_page(buf, xfer_offset):
     set_address(xfer_base + xfer_offset)
 
     # Send DNLOAD with fw data
-    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 2, __DFU_INTERFACE, buf, timeout())
+    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 2, __DFU_INTERFACE, buf, __TIMEOUT)
 
     # Execute last command
     check_status("write memory", __DFU_STATE_DFU_DOWNLOAD_BUSY)
@@ -317,7 +285,7 @@ def exit_dfu():
     set_address(0x08000000)
 
     # Send DNLOAD with 0 length to exit DFU
-    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 0, __DFU_INTERFACE, None, timeout())
+    __dev.ctrl_transfer(0x21, __DFU_DNLOAD, 0, __DFU_INTERFACE, None, __TIMEOUT)
 
     try:
         # Execute last command