BeagleBoard sdrc init writes reserved values
gadiyar at gmail.com
Wed Nov 10 11:13:00 EST 2010
On Wed, Nov 10, 2010 at 8:41 PM, Sascha Hauer <s.hauer at pengutronix.de> wrote:
> Hi Orjan,
> On Wed, Nov 10, 2010 at 09:55:21AM +0100, Orjan Friberg wrote:
>> In sdrc_init in board-beagle.c both
>> writel(0x1A, SDRC_REG(SYSCONFIG));
>> writel(0x18, SDRC_REG(SYSCONFIG));
>> sets bits 4:3 in the IDLEMODE field. The OMAP3 TRM (spruf98k) defines
>> 0x2 as the only valid value for this field, all others being marked as
>> "reserved - do not use". board-omap3evm.c does the same thing,
>> board-sdp343x.c does not.
>> Anyone knows where these settings come from? Derived from an older
>> version of the TRM? (I'm thinking there may have been a feature that
>> was discovered to be unreliable or not working as intended so it was
>> removed from the docs.)
> I have no idea. I'm pretty sure though that the value has been copied
> from some version of U-Boot or Xloader.
I agree - I think this is an accident - probably copied from older loader
versions and introduced in the first version that went here.
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