[h777] Increase some serial timeouts #7119

This solves the BF-888 refused to enter programming mode problem in
some cases where more time is needed waiting for radio identification
data.

This change also increases the timeout when uploading data blocks,
which is required for some individual radios.

chirp/drivers/h777.py

@@ -109,11 +109,19 @@ def _h777_enter_programming_mode(radio):
     elif ack != CMD_ACK:
         raise errors.RadioError("Radio refused to enter programming mode")
 
+    original_timeout = serial.timeout
     try:
         serial.write("\x02")
+        # At least one version of the Baofeng BF-888S has a consistent
+        # ~0.33s delay between sending the first five bytes of the
+        # version data and the last three bytes. We need to raise the
+        # timeout so that the read doesn't finish early.
+        serial.timeout = 0.5
         ident = serial.read(8)
     except:
         raise errors.RadioError("Error communicating with radio")
+    finally:
+        serial.timeout = original_timeout
 
     if not ident.startswith("P3107"):
         LOG.debug(util.hexprint(ident))
@@ -172,13 +180,20 @@ def _h777_write_block(radio, block_addr, block_size):
     LOG.debug("Writing Data:")
     LOG.debug(util.hexprint(cmd + data))
 
+    original_timeout = serial.timeout
     try:
         serial.write(cmd + data)
+        # Time required to write data blocks varies between individual
+        # radios of the Baofeng BF-888S model. The longest seen is
+        # ~0.31s.
+        serial.timeout = 0.5
         if serial.read(1) != CMD_ACK:
             raise Exception("No ACK")
     except:
         raise errors.RadioError("Failed to send block "
                                 "to radio at %04x" % block_addr)
+    finally:
+        serial.timeout = original_timeout
 
 
 def do_download(radio):