linux-kernel - Re: [PATCH v14 1/1] tty: serial: Add Nuvoton ma35d1 serial driver support

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Message-ID: <a2ff6965-e373-5bce-00cd-c8d9deb287c8@gmail.com>
Date:   Wed, 14 Jun 2023 09:18:51 +0800
From:   Jacky Huang <ychuang570808@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        lee@...nel.org, mturquette@...libre.com, sboyd@...nel.org,
        p.zabel@...gutronix.de, jirislaby@...nel.org, tmaimon77@...il.com,
        catalin.marinas@....com, will@...nel.org,
        devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-serial@...r.kernel.org, arnd@...db.de, soc@...nel.org,
        schung@...oton.com, mjchen@...oton.com,
        Jacky Huang <ychuang3@...oton.com>
Subject: Re: [PATCH v14 1/1] tty: serial: Add Nuvoton ma35d1 serial driver
 support

Dear Greg,


On 2023/6/13 下午 10:48, Greg KH wrote:
> On Tue, Jun 13, 2023 at 07:03:11PM +0800, Jacky Huang wrote:
>> Dear Greg,
>>
>>
>> On 2023/6/13 下午 06:29, Greg KH wrote:
>>> On Mon, Jun 12, 2023 at 02:53:55AM +0000, Jacky Huang wrote:
>>>> From: Jacky Huang <ychuang3@...oton.com>
>>>>
>>>> This adds UART and console driver for Nuvoton ma35d1 Soc.
>>>> It supports full-duplex communication, FIFO control, and
>>>> hardware flow control.
>>> You don't specify here what your tty device name is going to be, why?
>>>
>>> It's not written anywhere, is that intentional?
>>>
>>> Same for your tty major/minor, what numbers are you using that might
>>> also be in use by a different device in the system?
>>>
>>> thanks,
>>>
>>> greg k-h
>> I will add description about the tty name to the log.
>> In practical testing, we specified in the u-boot parameters
>> to use ttyNVT0 for the console, and it worked fine.
> Where did you pick that name from?  Why can't you use the "default" uart
> name instead?
>
> I thought we had a list of tty names around somewhere, but I can't find
> it right now...
>
> thanks,
>
> greg k-h

Initially, we were using the well-known ttyS, but it is used by the 8250 
driver.
Since the MA35D1 UART is incompatible with the 8250 driver, Andr raised
concerns about using ttyS.

To differentiate this UART from the incompatible 8250, we defined ttyNVT.
This name is specified in the driver's UART name and console name
structure, and other serial drivers follow a similar approach. For example,
we can find names like ttySA, ttySAC, ttySC, ttySIF, ttySTM, ttySUP,
and so on.

If you believe that this UART driver can use ttyS, I am more than willing to
make the modification. After all, some applications and scripts default to
using ttyS, and using ttyNVT can indeed cause some inconvenience in
certain situations.

Best regards,
Jacky Huang