snagrecover: dfu: Simplify timeout logic

The current logic to fetch and enforce timeouts during DFU downloads is
unecessarily complicated. Simplify it.

Signed-off-by: Romain Gantois <romain.gantois@bootlin.com>

src/snagrecover/protocols/dfu.py

@@ -96,29 +96,21 @@ def __init__(self, dev: usb.core.Device, stm32: bool = True):
 				"""
 				self.transfer_size = bMaxPacketSize0 * (wTransferSize // bMaxPacketSize0)
 				logger.info(f"Found DFU Functional descriptor: wTransferSize = {self.transfer_size}")
-
-
-	def check_timeout(timeout: int, t0: int) -> int:
-		t1 = round(time.time() * 1000)
-		if t1 - t0 < timeout:
-			logger.warning("Too soon to send another get_status command")
-			while round(time.time() * 1000) - t0 < timeout:
-				pass
-			t1 = round(time.time() * 1000)
-		return round(time.time() * 1000)
+		self.status_timeout = 100
 
 	def get_status(self) -> tuple:
+		# make sure to wait long enough after last get_status()
+		time.sleep(self.status_timeout / 1000.0)
 		# status = status polltimeout state iString
 		status = self.dev.ctrl_transfer(0xa1, 3, wValue=0, wIndex=0, data_or_wLength=6)# DFU_GETSTATUS
 		state = status[4]
-		timeout = int.from_bytes(bytes(status[1:3]), "little")
+		self.status_timeout = int.from_bytes(bytes(status[1:3]), "little")
 		logger.debug(f"DFU state: {state} DFU status: {DFU.status_codes[status[0]]}")
-		return (state,timeout)
+		return state
 
 	def download_and_run(self, blob: bytes, partid: int, offset: int, size: int, show_progress=False) -> bool:
 		self.set_partition(partid)
-		(state,timeout) = self.get_status()
-		t0 = round(time.time() * 1000)
+		state = self.get_status()
 		if state != DFU.state_codes["dfuIDLE"]:
 			raise ValueError(f"Incompatible state {state} detected")
 
@@ -130,36 +122,34 @@ def download_and_run(self, blob: bytes, partid: int, offset: int, size: int, sho
 		bytes_written = 0
 		for chunk in utils.dnload_iter(blob[offset:offset + size], self.transfer_size):
 			bytes_written += self.dev.ctrl_transfer(0x21, 1, wValue=block_index, wIndex=0, data_or_wLength=chunk)
-			progress = int(100 * bytes_written / size)
-			if show_progress:
-				print(f"\rprogress:{progress}%", end="")
+
 			# make sure to wait enough before sending next get_status
-			t0 = DFU.check_timeout(timeout, t0)
-			(state,timeout) = self.get_status()
+			state = self.get_status()
 			while state != DFU.state_codes["dfuDNLOAD-IDLE"]:
-				# make sure to wait enough before sending next get_status
-				t0 = DFU.check_timeout(timeout, t0)
-				(state,timeout) = self.get_status()
+				if state == DFU.state_codes["dfuERROR"]:
+					raise ValueError("DFU error code reported by device!")
+				state = self.get_status()
 			block_index += 1
+
 		# send zero-length download command to leave DFU mode and manifest
 		# firmware
 		bytes_written += self.dev.ctrl_transfer(0x21, 1, wValue=block_index, wIndex=0, data_or_wLength=None)
-		t0 = DFU.check_timeout(timeout, t0)
-		(state,timeout) = self.get_status()
+		state = self.get_status()
 		while state != DFU.state_codes["dfuIDLE"]:
-			t0 = DFU.check_timeout(timeout, t0)
 			if state == DFU.state_codes["dfuMANIFEST"]:
-				(state,timeout) = self.get_status()
+				state = self.get_status()
+				time.sleep(1)
 			elif state == DFU.state_codes["dfuMANIFEST-SYNC"]:
 				try:
 					# this fails on AM625, but is still necessary
-					(state,timeout) = self.get_status()
+					state = self.get_status()
 				except usb.core.USBError:
 					print("Could not read status after end of manifest phase")
 					return True
 			elif state == DFU.state_codes["dfuMANIFEST-WAIT-RESET"]:
 				self.detach()
 				return True
+
 		if show_progress:
 			print("")
 		logger.info("Done manifesting firmware")