linux-kernel - Re: [PATCH v4 01/11] mfd: add pruss mfd driver.

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Message-ID: <8B16A22172EC4753AD4E163CBD64C60F@subhasishg>
Date:	Fri, 20 May 2011 11:08:58 +0530
From:	"Subhasish Ghosh" <subhasish@...tralsolutions.com>
To:	"Arnd Bergmann" <arnd@...db.de>,
	"Mark Brown" <broonie@...nsource.wolfsonmicro.com>
Cc:	"Nori, Sekhar" <nsekhar@...com>,
	<linux-arm-kernel@...ts.infradead.org>,
	<davinci-linux-open-source@...ux.davincidsp.com>,
	<sachi@...tralsolutions.com>,
	"Samuel Ortiz" <sameo@...ux.intel.com>,
	"open list" <linux-kernel@...r.kernel.org>,
	"Watkins, Melissa" <m-watkins@...com>
Subject: Re: [PATCH v4 01/11] mfd: add pruss mfd driver.

Hi,

Anything regarding this.

>>> > My whole point has been that you register them from the main pruss 
>>> > driver
>>> > based on run-time data instead of compile-time pre-configured stuff in 
>>> > the
>>> > board file.
>>>
>>> I'm not so sure - if the usage is fixed as a result of the pins on the
>>> device being wired a CAN bus then it seems reasonable to tell the system
>>> about that so it'll stop the user trying to run SPI or something against
>>> it at runtime.
>>
>> I'm mostly worried about the case where the pins are not hardwired for
>> some specific function -- Subhasish was mentioning that these may be
>> implemented using a pluggable extension board and I want to make sure
>> that you are not required to recompile the kernel when changing the
>> extension board.
>>
>> However, you made a good point that in many cases it will be hardwired
>> so it may be valuable to preconfigure this in a way that does not require
>> scripts to set up variables in sysfs when you already know what is there.
>>
>> Note that my suggestion to put the device name into the firmware file
>> covers this case, because you can then simply ship a firmware blob that
>> matches the hardware configuration. Thinking about the future device
>> tree setup, you can even put the firmware blob itself into a property
>> in the device tree file.
>>
>
> I earlier had an implementation where I used a pruss_devices structure
> in the board file.
>
> http://linux.omap.com/pipermail/davinci-linux-open-source/
> 2011-March/022339.html.
>
> We can use this implementation along with the sysfs to load the devices
> runtime. The configs that I have in the board_file for the devices 
> structure, are fixed for a board. To swap the boards, we do not need to
> re-compile the kernel.
>
>
> 
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