[U-Boot] CONFIG_OF_EMBED/CONFIG_OF_SEPARATE and fdtcontroladdr

[Michal Simek]

Hi Simon,

I have create another thread because this can be discuss separately.

In board file there is this code (We discussed fdtcontroladdr separately).

#ifdef CONFIG_OF_EMBED
	/* Get a pointer to the FDT */
	gd->fdt_blob = _binary_dt_dtb_start;
#elif defined CONFIG_OF_SEPARATE
	/* FDT is at end of image */
	gd->fdt_blob = (void *)(_end_ofs + _TEXT_BASE);
#endif
	/* Allow the early environment to override the fdt address */
	gd->fdt_blob = (void *)getenv_ulong("fdtcontroladdr", 16,
						(uintptr_t)gd->fdt_blob);


Is there any reason to use CONFIG_ options here?
Because what I think will be the best is to remove CONFIG_ options and create
priorities and checking in at run time.

Priority should be:
1. variable
2. appended blob
3. compiled in blob

Because compiled in blob can be also used as safe blob for cases where fdtcontroladdr
points to nor flash which is broken. For this case current u-boot will fail because
fdt_prepare won't find out valid DTB.

Here is just skeleton to show you what design I would prefer.

int fdtdec_prepare_fdt(void *dtb)
{
         if (((uintptr_t)gd->fdt_blob & 3) || fdt_check_header(dtb)) {
                 return -1;
         }
         return 0;
}

void * fdt_addr = (void *)getenv_ulong("fdtcontroladdr", 16, (uintptr_t)gd->fdt_blob);
if(!fdt_prepare(fdt_addr)) {
	gd->fdt_blob = fdt_addr;
} else {
	fdt_addr = (void *)(_end_ofs + _TEXT_BASE);
	if(!fdt_prepare(fdt_addr)) {
		gd->fdt_blob = fdt_addr;
	} else {
		fdt_addr = _binary_dt_dtb_start; // FIXME special section for it
		if(!fdt_prepare(fdt_addr)) {
			gd->fdt_blob = fdt_addr;
		}
	}
}

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian