linux-kernel - Re: [PATCH] platform/x86: dell-uart-backlight: new backlight driver for DELL AIO

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Date:   Fri, 27 Oct 2017 10:21:09 +0800
From:   AceLan Kao <acelan.kao@...onical.com>
To:     Alan Cox <gnomes@...rguk.ukuu.org.uk>
Cc:     Mario.Limonciello@...l.com, Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>
Subject: Re: [PATCH] platform/x86: dell-uart-backlight: new backlight driver
 for DELL AIO

Hi Alex,

2017-10-27 0:10 GMT+08:00 Alan Cox <gnomes@...rguk.ukuu.org.uk>:
>
>> > +static int __init dell_uart_bl_init(void)
>> > +{
>> > +   ftty = filp_open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY, 0);
>>
>
> You have no idea what name is assigned. This doesn't work.
Yes, I did. The port is defined in BIOS as PNP0501 uart port,
so the port will be registered by 8250 PNP driver as ttyS* device.
And consider it's defined in the BIOS, so it should be the first uart
port on the system,
and ttyS0 would be his name.

>
> This isn't the way to do it any more because the 'tty from kernel'
> problem finally got fixed. You can attach it as a serdev directly to the
> kernel.
>
> Take a look at serdev_tty_port_register/serdev_tty_port_unreg
Yes, I'm studying serdev, but currently there are not many examples
for reference,
so I still have no clues how to implement it by serdev.
I'll try using serdev_tty_port_register/serdev_tty_port_unreg to
re-implement the driver.
Thanks.

>
> Alan



-- 
Chia-Lin Kao(AceLan)
http://blog.acelan.idv.tw/
E-Mail: acelan.kaoATcanonical.com (s/AT/@/)