linux-kernel - Re: [PATCHv3 2/2] serial: Add driver for the Altera UART

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Date:	Thu, 25 Mar 2010 08:54:09 +0800
From:	Thomas Chou <thomas@...ron.com.tw>
To:	Tobias Klauser <tklauser@...tanz.ch>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-serial@...r.kernel.org, gregkh@...e.de,
	nios2-dev@...c.et.ntust.edu.tw, linux-kernel@...r.kernel.org,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCHv3 2/2] serial: Add driver for the Altera UART

On 03/25/2010 12:24 AM, Tobias Klauser wrote:
> On 2010-03-24 at 12:05:27 +0100, Andrew Morton<akpm@...ux-foundation.org>  wrote:
>    
>> On Wed, 24 Mar 2010 07:47:47 +0100 Tobias Klauser<tklauser@...tanz.ch>  wrote:
>>      
>>> On 2010-03-23 at 22:54:59 +0100, Andrew Morton<akpm@...ux-foundation.org>  wrote:
>>>        
>>>> On Fri,  5 Mar 2010 17:52:23 +0100
>>>> Tobias Klauser<tklauser@...tanz.ch>  wrote:
>>>>
>>>>          
>>>>> +	sigs |= (altera_uart_getppdcd(port->line) ? TIOCM_CD : 0);
>>>>> +	sigs |= (altera_uart_getppdtr(port->line) ? TIOCM_DTR : 0);
>>>>>            
>>>> We seem to be missing a few things here.
>>>>
>>>> drivers/serial/altera_uart.c: In function 'altera_uart_get_mctrl':
>>>> drivers/serial/altera_uart.c:100: error: implicit declaration of function 'altera_uart_getppdcd'
>>>> drivers/serial/altera_uart.c:101: error: implicit declaration of function 'altera_uart_getppdtr'
>>>> drivers/serial/altera_uart.c: In function 'altera_uart_set_mctrl':
>>>> drivers/serial/altera_uart.c:114: error: implicit declaration of function 'altera_uart_setppdtr'
>>>>          
>>> These should usually be declared in a board specific header. There were
>>> compatibility macros in altera_uart.c which defined them to NOPs in case
>>> the board header did not properly define them. But I remove them as per
>>> request by Alan Cox (Message-ID: 20100301181920.3952c3e7@...rguk.ukuu.org.uk).
>>>
>>> Should we add them again (maybe to altera_uart.h)? Or would it be better
>>> to define a config symbol which is set in the board specific Kconfig and
>>> altera_uart depends on it?
>>>        
>> I guess the latter.
>>
>> There should have been a real implementation of these in the patchset -
>> otherwise the code can't be used or tested.  Confused.
>>      
> Sorry for the confusion.
>
> The last patchset I submitted (with the functions removed from
> altera_uart.c) was tested on a local branch, where I added the macros to
> a global board specific header. I didn't include that one in the patch.
>
> After looking at the code and it's history a bit closer (and also on the
> nios2 specific part) I realised that this macro was probably added
> because the driver was originally based on drivers/serial/mcf.c (the
> macros are present there too).
>
> Also there are currently no board configurations known to me that define
> these macros. So I'd suggest to remove the usage of these macros
> alltogether. We could still add them again (to the board specific part
> and with the config option then) in case there will be a board
> configuration implementing DTR/DCD lines on GPIOs.
>
> Could anyone on nios2-dev verify that there are currently no such board
> configurations?
>
> I'd remove the usage of the macros then and post an updated patch.
>    
Maybe we can add pointers to functions for the DCD/DTR in the struct 
altera_uart_platform_uart. Then board config file can define them if 
they implement these pins, NULL/0 otherwise.

struct altera_uart_platform_uart {
...
     int (*getppdcd)(...);    /* get DCD status */
...

};


static unsigned int altera_uart_get_mctrl(struct uart_port *port)
{
...
     if (port->getppdcd)
         sigs |= (port->getppdcd(...)) ? TIOCM_CD : 0);


- Thomas

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