Update notes on short packets.

1 files changed, 5 insertions, 6 deletions

diff --git a/usbh/src/pipe.rs b/usbh/src/pipe.rs
index 388b518..835ba86 100644
--- a/usbh/src/pipe.rs
+++ b/usbh/src/pipe.rs
@@ -202,7 +202,7 @@ impl Pipe<'_, '_> {
         buf: &mut T,
         nak_limit: usize,
         millis: &dyn Fn() -> usize,
-    ) -> Result<(usize), PipeErr> {
+    ) -> Result<usize, PipeErr> {
         // TODO: pull this from pipe descriptor for this addr/ep.
         let packet_size = 8;
 
@@ -217,6 +217,10 @@ impl Pipe<'_, '_> {
         // Read until we get a short packet (indicating that there's
         // nothing left for us in this transaction) or the buffer is
         // full.
+        //
+        // TODO: It is sometimes valid to get a short packet when
+        // variable length data is desired by the driver. cf §5.3.2 of
+        // USB 2.0.
         let mut bytes_received = 0;
         while bytes_received < db.len {
             // Move the buffer pointer forward as we get data.
@@ -231,11 +235,6 @@ impl Pipe<'_, '_> {
             bytes_received += recvd;
             trace!("!! read {} of {}", bytes_received, db.len);
             if recvd < packet_size {
-                // If we receive a short packet, we should be done
-                // here. It /may/ be possible to get a short packet
-                // and continue, but only if recvd is a word-sized
-                // multiple. I'm going to assume, for simplicity's
-                // sake, that that's not possible.
                 break;
             }