* BeagleBoard sdrc init writes reserved values
@ 2010-11-10 8:55 Orjan Friberg
2010-11-10 15:11 ` Sascha Hauer
0 siblings, 1 reply; 4+ messages in thread
From: Orjan Friberg @ 2010-11-10 8:55 UTC (permalink / raw)
To: barebox
In sdrc_init in board-beagle.c both
writel(0x1A, SDRC_REG(SYSCONFIG));
and
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.)
Thanks,
Orjan
--
Orjan Friberg
FlatFrog Laboratories AB
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: BeagleBoard sdrc init writes reserved values
2010-11-10 8:55 BeagleBoard sdrc init writes reserved values Orjan Friberg
@ 2010-11-10 15:11 ` Sascha Hauer
2010-11-10 16:13 ` Anand Gadiyar
0 siblings, 1 reply; 4+ messages in thread
From: Sascha Hauer @ 2010-11-10 15:11 UTC (permalink / raw)
To: Orjan Friberg; +Cc: barebox
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));
>
> and
>
> 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.
Sascha
--
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: BeagleBoard sdrc init writes reserved values
2010-11-10 15:11 ` Sascha Hauer
@ 2010-11-10 16:13 ` Anand Gadiyar
2010-11-11 11:55 ` Orjan Friberg
0 siblings, 1 reply; 4+ messages in thread
From: Anand Gadiyar @ 2010-11-10 16:13 UTC (permalink / raw)
To: Sascha Hauer; +Cc: barebox
On Wed, Nov 10, 2010 at 8:41 PM, Sascha Hauer <s.hauer@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));
>>
>> and
>>
>> 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.
- Anand
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: BeagleBoard sdrc init writes reserved values
2010-11-10 16:13 ` Anand Gadiyar
@ 2010-11-11 11:55 ` Orjan Friberg
0 siblings, 0 replies; 4+ messages in thread
From: Orjan Friberg @ 2010-11-11 11:55 UTC (permalink / raw)
To: Anand Gadiyar; +Cc: barebox
On 2010-11-10 17:13, Anand Gadiyar wrote:
>>> 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.
Ok, thanks. (We haven't seen any problems related to those settings, we
just checked them out of curiosity since we noticed there was a
difference between barebox/x-load/u-boot. )
--
Orjan Friberg
FlatFrog Laboratories AB
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2010-11-10 8:55 BeagleBoard sdrc init writes reserved values Orjan Friberg
2010-11-10 15:11 ` Sascha Hauer
2010-11-10 16:13 ` Anand Gadiyar
2010-11-11 11:55 ` Orjan Friberg
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