[U-Boot] [PATCH v2 0/5] arm, am33xx: update for the am33xx based siemens boards

[Vaibhav Bedia]

Hi Heiko,

On Mon, Nov 4, 2013 at 10:30 PM, Heiko Schocher <hs at denx.de> wrote:
> Hello Vaibhav Bedia,
>
> Am 04.11.2013 20:45, schrieb Vaibhav Bedia:
>
>> Hi Marek,
>>
>> On Mon, Nov 4, 2013 at 12:34 PM, Marek Vasut<marex at denx.de>  wrote:
>>>
>>> Dear Vaibhav Bedia,
>>>
>>>> On Mon, Nov 4, 2013 at 8:15 AM, Heiko Schocher<hs at denx.de>  wrote:
>>>> [...]
>>>>
>>>>> Hups, missed this EMail ... :-(
>>>>
>>>>
>>>> No problem. Happens all the time :)
>>>>
>>>>> Hmm.. some boards from siemens do not use the RTC, so this approach
>>>>> is not possible here ...
>>>>
>>>>
>>>> By unused do you mean it's not powered up or is it simply not
>>>> programmed?
>>>>
>>>> Even if the RTC is not programmed the register would still be there. I
>>>> don't have a
>>>> board with me to check the behavior but i am guessing the RTC
>>>> functionality doesn't
>>>> need to be used to make use of the scratchpad registers.
>>>
>>>
>>> If your hardware's IP block's clock are not ungated, the register access
>>> to that
>>> IP block will usually not work.
>>>
>> Yes, i understand that. However, in this case AFAICT the interface clock
>> is always present and hence it should be possible to use the RTC
>> registers.
>> Moreover, i just noticed Tom applied a bootcount patch for AM335x [1]
>> which
>> does use the scratchpad register that i am pointing to. So unless there's
>> some other board level difference that i am missing it should work.
>
>
> We see for example on the dxr2 board, that we cannot access the RTC
> registers ... also, they use it on other boards without RTC and all
> siemens boards should have the same manner.
>
> There is also a possibility to disable the RTC on am335x based boards,
> see:
>
> http://processors.wiki.ti.com/index.php/AM335x_Schematic_Checklist#RTC
>

Yeah, if the RTC is completely disabled as documented above then
the registers can't be accessed. In other cases i would expect the
register access to still work.

I just wanted to make sure that the usage of RTC for the bootcount
has been considered. With the recent changes by Tom at least the
other AM335x platforms use it so that's good.

If it's about keeping the approaches consistent on the Siemens boards
then i am fine with this.

Regards,
Vaibhav