Fix max PSBT length calculation

Also, do some prophylactic garbage collection to help avoid fragmentation on larger PSBTs

ports/stm32/boards/Passport/modules/actions.py

@@ -14,6 +14,7 @@
 
 import pyb
 import version
+import gc
 from files import CardMissingError, CardSlot
 # import main
 from uasyncio import sleep_ms
@@ -1356,11 +1357,18 @@ async def handle_psbt_data_format(data):
         try:
             from auth import sign_psbt_buf
 
+            gc.collect()
+            # print('Available RAM: psbt 1 = {}'.format(gc.mem_free()))
+
             # The data can be a string or may already be a bytes object
             if isinstance(data, bytes):
                 data_buf = data
             else:
                 data_buf = bytes(data, 'utf-8')
+
+            gc.collect()  # Try to avoid excessive fragmentation
+            # print('Available RAM: psbt 2 = {}'.format(gc.mem_free()))
+
             # print("data_buf={}".format(data_buf))
             system.show_busy_bar()
             dis.fullscreen('Analyzing...')

ports/stm32/boards/Passport/modules/auth.py

@@ -936,7 +936,8 @@ async def sign_psbt_buf(psbt_buf):
 
     UserAuthorizedAction.active_request = ApproveTransaction(psbt_len, approved_cb=done)
 
-    # kill any menu stack, and put our thing at the top
+    # Kill any menu stack, and put our thing at the top - whatever async chain started off this signing process will
+    # now resume and complete, and then the following action will become active.
     abort_and_goto(UserAuthorizedAction.active_request)
 
 

ports/stm32/boards/Passport/modules/constants.py

@@ -27,7 +27,7 @@ FLASH_CACHE_CHECKSUM_SIZE = 32
 FLASH_CACHE_MAX_JSON_LEN = FLASH_CACHE_BLOCK_SIZE - FLASH_CACHE_CHECKSUM_SIZE
 
 # Flash usage for PSBT signing
-PSBT_MAX_SIZE = (SPI_FLASH_TOTAL_SIZE - FLASH_CACHE_TOTAL_SIZE) // 2
+PSBT_MAX_SIZE = (SPI_FLASH_TOTAL_SIZE - FLASH_CACHE_TOTAL_SIZE)  # Total size available for both input and output
 
 # Flash firmware constants
 FW_MAX_SIZE = SPI_FLASH_TOTAL_SIZE - FLASH_CACHE_TOTAL_SIZE

ports/stm32/boards/Passport/modules/psbt.py

@@ -1392,16 +1392,31 @@ class psbtObject(psbtProxy):
             for k in self.unknown:
                 wr(k[0], self.unknown[k], k[1:])
 
+        # import micropython
+        # print('======================================')
+        # micropython.mem_info(1)
+        # print('======================================')
+
         # sep between globals and inputs
         out_fd.write(b'\0')
 
         for idx, inp in enumerate(self.inputs):
+            # print('Input {}: free mem={}'.format(idx, gc.mem_free()))
             inp.serialize(out_fd, idx)
             out_fd.write(b'\0')
+            gc.collect()  # Give collector a chance to run to help avoid fragmentation
 
         for idx, outp in enumerate(self.outputs):
+            # print('Output {}: free mem={}'.format(idx, gc.mem_free()))
             outp.serialize(out_fd, idx)
             out_fd.write(b'\0')
+            gc.collect()  # Give collector a chance to run to help avoid fragmentation
+
+        # print('After serialize(): free mem={}'.format(gc.mem_free()))
+
+        # print('======================================')
+        # micropython.mem_info(1)
+        # print('======================================')
 
     def sign_it(self):
         # txn is approved. sign all inputs we can sign. add signatures

ports/stm32/boards/Passport/modules/sflash.py

@@ -15,10 +15,10 @@
 # - it wants to waste 4k on a buffer
 #
 # Layout for project:
-#   - 768 PSBT incoming (MAX_TXN_LEN)
-#   - 768 PSBT outgoing (MAX_TXN_LEN)
+#   - 917K PSBT incoming (MAX_TXN_LEN)
+#   - 917K PSBT outgoing (MAX_TXN_LEN)
 #   - The previous two regions are only used when signing PSBTs.
-#   - The same space is used to hold firmware updates.
+#   - The same space is also used to hold firmware updates.
 #   - 256k flash cache - similar to settings, but for UTXOs and wallet address cache
 #
 import machine

ports/stm32/boards/Passport/trezor-firmware/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-bip32.h

@@ -625,12 +625,12 @@ STATIC mp_obj_t mod_trezorcrypto_bip32_deserialize(mp_obj_t value, mp_obj_t vers
     HDNode hdnode;
     uint32_t fingerprint;
     if (_is_public) {
-      printf("Calling hdnode_deserialize_public()\n");
+      // printf("Calling hdnode_deserialize_public()\n");
       if (hdnode_deserialize_public(valueb.buf, _version, SECP256K1_NAME, &hdnode, &fingerprint) < 0) {
           mp_raise_ValueError("Failed to deserialize public");
       }
     } else {
-      printf("Calling hdnode_deserialize_private()\n");
+      // printf("Calling hdnode_deserialize_private()\n");
       if (hdnode_deserialize_private(valueb.buf, _version, SECP256K1_NAME, &hdnode, &fingerprint) < 0) {
           mp_raise_ValueError("Failed to deserialize private");
       }