extmod/btstack: Schedule notify/indicate/write ops for bg completion.

The goal of this commit is to allow using ble.gatts_notify() at any time,
even if the stack is not ready to send the notification right now.  It also
addresses the same issue for ble.gatts_indicate() and ble.gattc_write()
(without response).  In addition this commit fixes the case where the
buffer passed to write-with-response wasn't copied, meaning it could be
modified by the caller, affecting the in-progress write.

The changes are:

- gatts_notify/indicate will now run in the background if the ACL buffer is
  currently full, meaning that notify/indicate can be called at any time.

- gattc_write(mode=0) (no response) will now allow for one outstanding
  write.

- gattc_write(mode=1) (with response) will now copy the buffer so that it
  can't be modified by the caller while the write is in progress.

All four paths also now track the buffer while the operation is in
progress, which prevents the GC free'ing the buffer while it's still
needed.

1 files changed, 1 insertions, 1 deletions

diff --git a/extmod/modbluetooth.h b/extmod/modbluetooth.h
index c8b8dc63f..a232ee2d1 100644
--- a/extmod/modbluetooth.h
+++ b/extmod/modbluetooth.h
@@ -199,7 +199,7 @@ int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t
 // Notify the central that it should do a read.
 int mp_bluetooth_gatts_notify(uint16_t conn_handle, uint16_t value_handle);
 // Notify the central, including a data payload. (Note: does not set the gatts db value).
-int mp_bluetooth_gatts_notify_send(uint16_t conn_handle, uint16_t value_handle, const uint8_t *value, size_t *value_len);
+int mp_bluetooth_gatts_notify_send(uint16_t conn_handle, uint16_t value_handle, const uint8_t *value, size_t value_len);
 // Indicate the central.
 int mp_bluetooth_gatts_indicate(uint16_t conn_handle, uint16_t value_handle);