[U-Boot] of-platdata address map decode for 64-bits

[Kever Yang]

Hi Simon,

On 02/08/2017 01:10 PM, Simon Glass wrote:
> Hi Kever,
>
> On 4 February 2017 at 16:30, Kever Yang <kever.yang at rock-chips.com> wrote:
>> Hi Simon,
>>
>>      For rk3399, the data for sdram driver in dts is big, I don't want to do
>> the copy for it,
> Are you referring to the call to fdtdec_get_int_array()? Don't you
> have heaps of SRAM though? So why does it matter? If you are really
> worried about it you could loop through the data word by word instead.

I don't understand how to "loop through the data word by word".
> But why?
>
>> so I think use of-platdata is a good method, and for image size, its
>> smaller, then it's sooner to load.
> Yes it reduces the image size, but only by a small amount. I have not
> checked it on ARM64 but it should be around 5KB. I don't think it is
> very important.

Here is why I insist on no more extra operation and extra code in SPL,
- The CPU in bootrom usually running in pretty low frequency, the copy 
may be slow;
- The eMMC in bootrom is running in pretty low frequency, the read is slow;
- Not like kernel or U-Boot, I don't think the dts values much for SPL,
     Most of driver used in SPL is one time init, and may totally 
different in
different SoC, including clock/cru driver, pinctrl/grf driver, dram 
driver, only
storage driver is shared in different SoC and different boot stage.
IMO, the SPL suppose to be simple, fast to init dram and load next stage 
image(if
we do not go back to bootrom).

For production, I have do many times to speed up the boot duration in 
different SoCs,
so I hope the upstream U-Boot for Rockchip SoC is not only for 
developers. We should
care about the size even if the size is enough for boot, the size design 
is not only consider
the boot, but also for some application in system suspend which dram 
suspend.

Thanks,
- Kever
>
> Regards,
> Simon
>
>
>> Thanks,
>> - Kever
>>
>> On 01/26/2017 10:22 PM, Simon Glass wrote:
>>> Hi Kever,
>>>
>>> On 17 January 2017 at 23:37, Kever Yang <kever.yang at rock-chips.com> wrote:
>>>> Hi Simon,
>>>>
>>>>       For my rk3399(64bit) dts, the address is described as below:
>>>> #address-cells = <2>;
>>>> reg = <0x0 0xfe320000 0x0 0x4000>;
>>>>
>>>> not like 32-bit soc which reg address describe like:
>>>> reg = <0xfe320000 0x4000>;
>>>>
>>>>       There should have some update for this dts decode, right?
>>>> like:
>>>> map_sysmem()
>>>> regmap_init_mem_platdata()
>>>>
>>>>       Do you have a idea to update all these kind of function call?
>>>> It will be very great if you can send a patch for it.
>>>>
>>>> Thanks,
>>>> - Kever
>>>>
>>> Yes I think so.
>>>
>>> But first I'd like to understand why we need to use of-platdata on
>>> this very modern SoC. Can you tell me the maximum SPL size you can
>>> support on this SoC? I thought you had removed the 30KB limit?
>>>
>>> Using of-platdata only saves 3-4KB.
>>>
>>> Regards,
>>> Simon
>>>
>>>
>>>
>>
>
>