[meta-freescale] smarc-samx6i board support

[Otavio Salvador]

On Fri, Dec 12, 2014 at 6:22 AM, Nikita Yushchenko
<nyushchenko at dev.rtsoft.ru> wrote:
> Hello Otavio
>
> Thanks for you replies.
>
> I'm taking a time out to port my code to yocto master / 3.10.31 kernel,
> to prepare u-boot recipe and to address issues discussed in the mail.

Right; I agree that the U-Boot should be the starting point here but I
also expect it to be changed during the Linux kernel port as sometimes
you make use its facilities to solve a problem / design requirement.

>>> *) Support for hardware variations.
>> ...
>> If you ask me what would be the ideal solution I'd say it'd be to use
>> the recently added U-Boot SPL support (in U-Boot 2014.10 it has
>> support, use master from DENX for now work) as it would allow you to
>> use a single image and boot the Quad, Dual, DualLite and Solo variants
>> in a single image.
>
> Hmm... could you provide a bit more details on this?
> Does SPL stand for "secondary program loader"? How does this relate to
> having single image for different hw configs?

Because the SPL is capable of identify the CPU type (Q, D, DL, S) and
load the right memory configuration. This is very good and easy a lot
the maintenance work for the BSP team while also makes customers life
easier as remove the CPU type compatibility from the manufacturing
process. Another nice feature is the possibility of boot speed
optimization as we can load the Linux kernel directly and avoid the
U-Boot CLI interface and hardware initialization which is not required
for boot.

Regarding the different hardware configs, if you have a way to detect
the availability of a carrier board, LCD, ..., you have the
possibility to choose the right DeviceTree accordingly.

>>> *) Display selection
>>> ...
>> Take a look at how Boundary Devices has solved this. Their solution is
>> the most user-friendly one IMO.
>
> Do you mean what is described here -
> http://boundarydevices.com/configuring-i-mx6-machines-different-screens-nitrogen6x-sabre-lite/
> ?
>
> I still do not understand how this correlates with configuring displays
> in device tree (just overrides it? then, what for to have display
> configuration in device tree at all?)...

No; this script has some nice ways to figure if a panel A or B is
connected. This can be user to choose the right DeviceTree to load,
for example.

-- 
Otavio Salvador                             O.S. Systems
http://www.ossystems.com.br        http://code.ossystems.com.br
Mobile: +55 (53) 9981-7854            Mobile: +1 (347) 903-9750