linux-kernel - Re: [PATCH v5 5/7] Bluetooth: Extend btuart driver for join more vendor devices

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Message-Id: <70616B99-5A2D-417A-8815-246700EEF4E2@holtmann.org>
Date:   Sat, 14 Jul 2018 18:44:49 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     sean.wang@...iatek.com
Cc:     robh+dt@...nel.org, mark.rutland@....com,
        Johan Hedberg <johan.hedberg@...il.com>,
        devicetree@...r.kernel.org, linux-bluetooth@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 5/7] Bluetooth: Extend btuart driver for join more
 vendor devices

Hi Sean,

> Adding an independent btuart.h header allows these essential definitions
> can be reused in vendor driver. Also, struct btuart_vnd is extended with
> additional callbacks such as .init initializing vendor data, .shtudown,
> .recv and .send supporting SoC specific framing for that btuart can
> simply adapt to various Bluetooth uart-based devices.
> 
> Signed-off-by: Sean Wang <sean.wang@...iatek.com>
> ---
> drivers/bluetooth/btuart.c | 73 ++++++++++++++++++++++++----------------------
> drivers/bluetooth/btuart.h | 30 +++++++++++++++++++
> 2 files changed, 68 insertions(+), 35 deletions(-)
> create mode 100644 drivers/bluetooth/btuart.h
> 
> diff --git a/drivers/bluetooth/btuart.c b/drivers/bluetooth/btuart.c
> index a900aac..65d0086 100644
> --- a/drivers/bluetooth/btuart.c
> +++ b/drivers/bluetooth/btuart.c
> @@ -33,35 +33,11 @@
> #include <net/bluetooth/hci_core.h>
> 
> #include "h4_recv.h"
> +#include "btuart.h"
> #include "btbcm.h"
> 
> #define VERSION "1.0"
> 
> -struct btuart_vnd {
> -	const struct h4_recv_pkt *recv_pkts;
> -	int recv_pkts_cnt;
> -	unsigned int manufacturer;
> -	int (*open)(struct hci_dev *hdev);
> -	int (*close)(struct hci_dev *hdev);
> -	int (*setup)(struct hci_dev *hdev);
> -};
> -
> -struct btuart_dev {
> -	struct hci_dev *hdev;
> -	struct serdev_device *serdev;
> -
> -	struct work_struct tx_work;
> -	unsigned long tx_state;
> -	struct sk_buff_head txq;
> -
> -	struct sk_buff *rx_skb;
> -
> -	const struct btuart_vnd *vnd;
> -};

I really like to avoid this since it is not clean. Frankly I prefer to keep the btuart.c driver for drivers that really just use H:4 as transport protocol. If the protocol is only H:4 alike and has extra headers, then it should be a separate driver.

The common H:4 handling is abstracted in h4_recv.h already anyway and we can add more pieces if needed. However I also wonder since you have extra framing that the complex H:4 state keeping might be not needed at all. So it could be simplified.

Regards

Marcel