linux-kernel - Re: [PATCH v2 13/13] tty: pruss SUART driver

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Date:	Wed, 23 Feb 2011 11:00:25 +0530
From:	"Subhasish Ghosh" <subhasish@...tralsolutions.com>
To:	"Greg KH" <gregkh@...e.de>, "Alan Cox" <alan@...rguk.ukuu.org.uk>
Cc:	"Arnd Bergmann" <arnd@...db.de>,
	<linux-arm-kernel@...ts.infradead.org>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	<sachi@...tralsolutions.com>,
	<davinci-linux-open-source@...ux.davincidsp.com>, <nsekhar@...com>,
	"open list" <linux-kernel@...r.kernel.org>, <m-watkins@...com>,
	"Stalin Srinivasan" <stalin.s@...tralsolutions.com>
Subject: Re: [PATCH v2 13/13] tty: pruss SUART driver

I could not follow the recommendations clearly.
This is just to clarify.

Currently, I have the following files for the suart implementation:

drivers/tty/serial/da8xx_pruss/pruss_suart_api.h
drivers/tty/serial/da8xx_pruss/pruss_suart_err.h
drivers/tty/serial/da8xx_pruss/pruss_suart_regs.h
drivers/tty/serial/da8xx_pruss/pruss_suart_board.h
drivers/tty/serial/da8xx_pruss/pruss_suart_mcasp.h
drivers/tty/serial/da8xx_pruss/pruss_suart_utils.h

drivers/tty/serial/da8xx_pruss/pruss_suart_api.c
drivers/tty/serial/da8xx_pruss/pruss_suart.c
drivers/tty/serial/da8xx_pruss/pruss_suart_utils.c

Of these, I will be removing pruss_suart_err.h as part of the Linux error 
code cleanup.
But, I need to keep at least  pruss_suart_board.h as a separate file, as 
this defines
configurations which will be often modified by users, I don't want to mix it 
with other files.

Should I combine rest of the headers into a single file ? and keep the other 
three .c files under "drivers/tty/serial/"
and remove the da8xx_pruss directory altogether.


--------------------------------------------------
From: "Greg KH" <gregkh@...e.de>
Sent: Tuesday, February 22, 2011 8:07 PM
To: "Subhasish Ghosh" <subhasish@...tralsolutions.com>
Cc: "Arnd Bergmann" <arnd@...db.de>; <linux-arm-kernel@...ts.infradead.org>; 
"Thomas Gleixner" <tglx@...utronix.de>; "Alan Cox" 
<alan@...rguk.ukuu.org.uk>; <sachi@...tralsolutions.com>; 
<davinci-linux-open-source@...ux.davincidsp.com>; <nsekhar@...com>; "open 
list" <linux-kernel@...r.kernel.org>; <m-watkins@...com>
Subject: Re: [PATCH v2 13/13] tty: pruss SUART driver

> On Tue, Feb 22, 2011 at 02:12:32PM +0530, Subhasish Ghosh wrote:
>> Hello,
>>
>> I had kept separate files to affirm the modularity and ease of
>> portability of the system.
>>
>> There are three different interfaces,
>> 1. The Linux driver interface
>> 2. The PRU control interface
>> 3. The McASP serializer interface.
>>
>> To maintain modularity, I  had classified the files respectively as :
>> 1.  pruss_suart.c
>> 2.  pruss_suart_api.c
>> 3.  pruss_suart_utils.c
>>
>> This is not a single device which can be expressed as a single file,
>> but functionally different devices logically cascaded together to
>> work in unison.
>>
>> We use the PRU for packet processing, but the actual data is
>> transmitted/received through the
>> McASP, which we use as a serializer.
>>
>> I feel to combine these disparate functionalities into a single file
>> will not
>>
>> 1. Help better understanding the device. I mean, why should a TTY
>> UART driver be aware of the McASP or the PRU.
>> 2. In case of a bug in the API layer or McASP, the driver need not
>> be touched, thus improve maintainability.
>> 3. If we need to port it to another Linux version, just editing the
>> driver file should suffice, this will reduce bugs while porting.
>
> If your code is in the kernel tree, you do not need to ever port it to a
> new version, as it will happen automatically as new kernels are
> released, so this really isn't anything to worry about.
>
>> To me, combining all of these into a single file only creates a
>> mess. This is the reason I had separated them into different files!!
>> I don't understand why should it be better to have all of these into
>> a single file.
>
> As Alan stated, just use 3 files in the directory with the other
> drivers, you don't need a subdir for something small like this.
>
> thanks,
>
> greg k-h 

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