[Buildroot] [PATCH 1/1] rpi0w: added support for Raspberry Pi Zero W

[Peter Seiderer <ps.report@gmx.net>]

Hello Yves, Thomas,

On Wed, 21 Jun 2017 20:35:21 +0000, Yves Deweerdt <yves.deweerdt.linux@gmail.com> wrote:

> Hello Peter, Thomas,
> 
> 
> > > For rpi3, is it correct that it seems that when running in 64bit mode you
> > > should add enable_uart=1 and for 32 bit mode you don't need to add it?
> >
> > Never tried the 64bit mode (yet), any reference for this?
> >
> >
> > Hello Peter, Thomas,
> 
> I just had a closer look to the raspberrypi3 and raspberrypi3_64 story.
> It seems that on the 32 bit version the overlay is being used, which means
> that the console is being put on /dev/ttyS0 in stead of /dev/ttyAMA0, which
> means that /dev/ttyAMA0 is available already if you plan to use bluetooth.
> On the 64 bit version, the console is put on /dev/ttyAMA0, so that means
> that if you want to enable bluetooth, you need to do the same modifications
> again to move console over to /dev/ttyS0 and free up /dev/ttyAMA0 for
> bluetooth.
> 
> I don't know if there are any drawbacks in using the /dev/ttyS0 on the 64
> bit version. If not, I would recommend making the 32 bit version and the 64
> bit version do the same thing, and at that moment the --aarch64 option in
> the post-image.sh script could be completely removed.

The --aarch64 options sets the important 'arm_control=0x200' to enable to
boot the 64bit kernel, this needs to be kept (maybe change the post-image.sh
script to support multiple cmdl options and separate overlay and aarch64)...

But I had no success to enable the serial console for raspberrypi3_64 using
only the overlay, only 'enable_uart=1' worked for me...

Regards,
Peter


> 
> Kind regards,
> 
> Yves
> 
> >
> >