Re: [RFC 4/7] Bluetooth: hci_uart: Add support for word alignment

Marcel Holtmann
2016-08-16T07:05:30Z

Hi Sebatian,

> 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.

> int (*recv)(struct hci_dev *hdev, struct sk_buff *skb);

Regards

Marcel