linux-kernel - Re: [PATCH v2 2/3] tty: Implement default fallback serial8250_rs485

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Message-ID: <563E08C6.7000505@hurleysoftware.com>
Date:	Sat, 7 Nov 2015 09:20:54 -0500
From:	Peter Hurley <peter@...leysoftware.com>
To:	"Matwey V. Kornilov" <matwey@....msu.ru>
Cc:	Greg KH <gregkh@...uxfoundation.org>, jslaby@...e.com,
	linux-serial@...r.kernel.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] tty: Implement default fallback
 serial8250_rs485_config

On 11/07/2015 08:51 AM, Matwey V. Kornilov wrote:
> 2015-11-07 15:29 GMT+03:00 Peter Hurley <peter@...leysoftware.com>:
>> Hi Matwey,
>>
>> On 11/07/2015 05:09 AM, Matwey V. Kornilov wrote:
>>> When 8250 driver doesn't have its own hardware RS485 support and doesn't
>>> want to override rs485_config callback, then default
>>> serial8250_rs485_config is used. It just stores supplied by user-space
>>> config.
>>>
>>> Signed-off-by: Matwey V. Kornilov <matwey@....msu.ru>
>>> ---
>>>  drivers/tty/serial/8250/8250_core.c | 10 ++++++++++
>>>  1 file changed, 10 insertions(+)
>>>
>>> diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
>>> index 3912646..8f292da 100644
>>> --- a/drivers/tty/serial/8250/8250_core.c
>>> +++ b/drivers/tty/serial/8250/8250_core.c
>>> @@ -395,6 +395,12 @@ static void serial8250_release_rsa_resource(struct uart_8250_port *up)
>>>       }
>>>  }
>>>  #endif
>>> +static int serial8250_rs485_config(struct uart_port *port,
>>> +                             struct serial_rs485 *rs485)
>>> +{
>>> +     port->rs485 = *rs485;
>>> +     return 0;
>>> +}
>>>
>>>  static const struct uart_ops *base_ops;
>>>  static struct uart_ops univ8250_port_ops;
>>> @@ -990,6 +996,10 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
>>>               uart->port.rs485        = up->port.rs485;
>>>               uart->dma               = up->dma;
>>>
>>> +             /* Use software RS485 support when hardware one is not available */
>>> +             if (!(uart->capabilities & UART_CAP_HW485) && !uart->port.rs485_config)
>>> +                     uart->port.rs485_config = serial8250_rs485_config;
>>
>> To setup a default 8250 port function,
>> 1. define the default 8250 port function in 8250/8250_port.c
>> 2. add the port function to the dispatch table (serial8250_pops)
> 
> rs485_config is not a member of struct uart_ops, should I add it there?

Whoops, sorry! :/
For now, assign the default 8250 port function in serial8250_set_defaults().

Regards,
Peter Hurley

>> 3. add a test for 8250 sub-driver override in serial8250_register_8250_port()
>>    Eg.,
>>
>>                 if (up->port.rs485_config)
>>                         uart->port.rs485_config = up->port.rs485_config;
>>
>> Regards,
>> Peter Hurley
>>
>>>               /* Take tx_loadsz from fifosize if it wasn't set separately */
>>>               if (uart->port.fifosize && !uart->tx_loadsz)
>>>                       uart->tx_loadsz = uart->port.fifosize;
>>>
>>
> 
> 
> 

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