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Date: Thu, 23 Sep 2010 08:42:46 -0500
Message-ID: <AANLkTi=1QqxE3P_+5goP43YNvcaQLjQUk5XWo-Oq51iW@mail.gmail.com>
Subject: Re: [PATCH v2] omap: beagle: add support for wl1271 on the board file
From: Robert Nelson <robertcnelson@gmail.com>
To: Luciano Coelho <luciano.coelho@nokia.com>
Cc: "linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
	"tony@atomide.com" <tony@atomide.com>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	Ohad Ben-Cohen <ohad@wizery.com>
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On Thu, Sep 23, 2010 at 7:52 AM, Luciano Coelho
<luciano.coelho@nokia.com> wrote:
> On Thu, 2010-09-23 at 14:03 +0200, ext Robert Nelson wrote:
>> On Thu, Sep 23, 2010 at 5:30 AM, Grazvydas Ignotas <notasas@gmail.com> wrote:
>> > On Thu, Sep 23, 2010 at 11:20 AM, Luciano Coelho
>> > <luciano.coelho@nokia.com> wrote:
>> >> Add board configuration for the wl1271 daughter board. ?This patch is based
>> >> on Ohad Ben-Cohen's patches for Zoom boards.
>> >
>> > Hm can that daughter board be detected? With your patch all beagle
>> > users will get GPIO139 toggled, and if someone has that wired to
>> > chainsaw switch somebody might get hurt.
>>
>> Expansion boards really need to follow:
>>
>> http://elinux.org/BeagleBoardPinMux#Expansion_boards
>>
>> Is there any eeprom on i2c bus #2 for identification on this board?
>
> Hmmm... <checking the schematics>
>
> Yes, it does. :) This makes perfect sense.
>
> My bootloader (U-Boot 2010.03) doesn't seem to detect it, though:
>
> <clip>
> Probing for expansion boards, if none are connected you'll see a
> harmless I2C error.
>
> No EEPROM on expansion board
> <clip>

I'd first add the board to the list on the wiki to protect the
expansion board id.

Here's the current patch for u-boot for these expansion boards, it
only implements id's for the boards listed at the time.

http://www.sakoman.com/cgi-bin/gitweb.cgi?p=u-boot.git;a=commit;h=95993d1fee62ef64b2f58c1e186176ca9033c35e

> Do I need a special bootloader?
>
> Is there any standard way to recognize the expansion board and configure
> it properly?

Yeap, you need a special bootloader, which is a downside to the
current implementation...  It relies on u-boot to do the i2c probing
and detect which expansion board is connected, it would be nice if the
kernel could do it on it's own..

So currently u-boot probes, then notifies the kernel thru a "buddy"
variable that gets passed with the bootargs..

board-omap3beagle.c then parse's the "buddy" variable to setup the
expansion device, like as shown for the zippy1/2 expansion boards:

http://cgit.openembedded.org/cgit.cgi/openembedded/tree/recipes/linux/linux-omap-psp-2.6.32/0007-ARM-OMAP-beagleboard-Add-infrastructure-to-do-fixups.patch

(note there are patches applied before this and after, so it's won't
apply cleanly to mainline)

Regards,

-- 
Robert Nelson
http://www.rcn-ee.com/