linux-kernel - Re: [PATCH v3] tty: serial: don't do termios for BTIF

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Date:   Wed, 17 Jun 2020 11:58:20 +0800
From:   <sean.wang@...iatek.com>
To:     <andy.shevchenko@...il.com>
CC:     <andriy.shevchenko@...ux.intel.com>, <gregkh@...uxfoundation.org>,
        <steven.liu@...iatek.com>, <arnd@...db.de>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <Ryder.Lee@...iatek.com>,
        <sean.wang@...iatek.com>, <tthayer@...nsource.altera.com>,
        <linux-serial@...r.kernel.org>, <jslaby@...e.com>,
        <matthias.bgg@...il.com>, <sr@...x.de>,
        <mika.westerberg@...ux.intel.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3] tty: serial: don't do termios for BTIF

From: Sean Wang <sean.wang@...iatek.com>

>>
>> From: Sean Wang <sean.wang@...iatek.com>
>>
>> Bluetooth Interface (BTIF) is designed dedicatedly for MediaTek SOC
>> with BT in order to be instead of the UART interface between BT module
>> and Host CPU, and not exported to user space to access.
>>
>> As the UART design, BTIF will be an APB slave and can transmit or
>> receive data by MCU access, but doesn't provide termios function like
>> baudrate and flow control setup.
>>
>> Even LCR on offset 0xC that is just a FAKELCR a. If FAKELCR[7] is
>> equaled to 1, RBR(0x00), THR(0x00), IER(0x04)
>>    will not be readable/writable.
>>
>> b. If FAKELCR is equaled to 0xBF, RBR(0x00), THR(0x00), IER(0x04),
>>    IIR(0x08), and LSR(0x14) will not be readable/writable.
>>
>> So adding a new capability 'UART_CAP_NTIO' for the unusual unsupported
>> case.
>>
>> Fixes: 1c16ae65e250 ("serial: 8250: of: Add new port type for MediaTek
>> BTIF controller on MT7622/23 SoC")
>> Cc: Steven Liu <steven.liu@...iatek.com>
>
>> Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
>
>I didn't suggest this change. I only commented on the name of the macro.

my fault. i will remove the tag from next version.

>
>> Signed-off-by: Sean Wang <sean.wang@...iatek.com>
>> Signed-off-by: Ryder Lee <ryder.lee@...iatek.com>
>>
>> --