Hi Marcel,

On Tue, Aug 16, 2016 at 09:05:19AM +0200, Marcel Holtmann wrote:

Hi Sebatian,

quoted

This will be used by Nokia's H4+ protocol, which
adds padding to packets to reach word alignment.
---
drivers/bluetooth/hci_h4.c   | 10 ++++++++++
drivers/bluetooth/hci_uart.h |  1 +
2 files changed, 11 insertions(+)

diff --git a/drivers/bluetooth/hci_h4.c b/drivers/bluetooth/hci_h4.c
index 635597b6e168..a934e4eb692b 100644
--- a/drivers/bluetooth/hci_h4.c
+++ b/drivers/bluetooth/hci_h4.c

@@ -253,11 +253,21 @@ struct sk_buff *h4_recv_buf(struct hci_dev *hdev, struct sk_buff *skb,

			}

			if (!dlen) {
+				if ((&pkts[i])->wordaligned && !(skb->len % 2)) {
+					buffer++;
+					count--;
+				}
+
				/* No more data, complete frame */
				(&pkts[i])->recv(hdev, skb);
				skb = NULL;
			}
		} else {
+			if ((&pkts[i])->wordaligned && !(skb->len % 2)) {
+				buffer++;
+				count--;
+			}
+
			/* Complete frame */
			(&pkts[i])->recv(hdev, skb);
			skb = NULL;

diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index 839bad1d8152..a7d67aec3632 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h

@@ -121,6 +121,7 @@ struct h4_recv_pkt {

	u8  loff;	/* Data length offset in header */
	u8  lsize;	/* Data length field size */
	u16 maxlen;	/* Max overall packet length */
+	bool wordaligned;	/* packets are word aligned */

I wonder if not a u8 align would be a way better choice here. We
set it to 1 for all existing packet types. And the Nokia driver
can use 2 here.

Sounds less hacky than my approach. Also it made me notice, that my
code is not safe, since the buffer size is not checked. I will use
u8 align and fix the buffer size check.

-- Sebastian