[U-Boot] [PATCH] rpi: Fix device tree path on ARM64

[Tuomas Tynkkynen <tuomas@tuxera.com>]

On Thu, 5 Jan 2017 16:44:43 -0700
Stephen Warren <swarren@wwwdotorg.org> wrote:

> On 01/03/2017 03:39 AM, Tuomas Tynkkynen wrote:
> > The directory structure of device tree files produced by the kernel's
> > 'make dtbs_install' is different on ARM64, the RPi3 device tree file is
> > in a 'broadcom' subdirectory there. Make the set_fdtfile function account
> > for this so that the distro boot scripts can locate the DTB file.
> 
> I'm not 100% sure there's an expectation/guarantee that "make 
> dtbs_install" will be used to create the DTB layout that the bootloader 
> uses, although I suppose this is a reasonable thing to do.
> 

It certainly would be nice from the distro's point of view to have the same
scripts work on both ARM and ARM64.

> > diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c
> 
> >  static void set_fdtfile(void)
> 
> > -	fdtfile = model->fdtfile;
> > +	if (IS_ENABLED(CONFIG_ARM64))
> > +		strcat(fdtfile, "broadcom/");
> > +	strcat(fdtfile, model->fdtfile);
> 
> Instead of writing code for this, and in particular code that doesn't 
> check for buffer size/overflow/..., wouldn't it be better to simply edit 
> the RPi 3 entry in rpi_models_new_scheme[] to contain "broadcom/" in the 
> DTB filename string?
> 

I did it this way to keep the 32-bit builds looking in the old location,
as that's where it was planned to be added for 32-bit ARM:

https://patchwork.kernel.org/patch/9148261/

I did consider some preprocessor magic and compile-time string concatenation
but this seemed a cleaner way.