[PATCH] fdt: Fix bootm_low handling

[Marek Vasut]

According to README CFG_SYS_BOOTMAPSZ section, in case both "bootm_low" and
"bootm_size" variables are defined, "bootm_mapsize" variable is not defined
and CFG_SYS_BOOTMAPSZ macro is not defined, all data for the Linux kernel
must be between "bootm_low" and "bootm_low" + "bootm_size".

Currently, for systems with DRAM between 0x4000_0000..0x7fff_ffff and with
e.g. bootm_low=0x60000000 and bootm_size=0x10000000, the code will attempt
to reserve memory from 0x4000_0000..0x4fff_ffff, which is incorrect. This
is because "bootm_low" is not taken into consideration correctly.

The last parameter of lmb_alloc_base() is the maximum physical address of
the to be reserved LMB area. Currently this is the start of DRAM bank that
is considered for LMB area reservation + min(DRAM bank size, bootm_size).
In case bootm_low is set to non-zero, this maximum physical address has to
be shifted upward, to min(DRAM bank start + size, bootm_low + bootm_size),
otherwise the reserved memory may be below bootm_low address.

In case of multiple DRAM banks, the current change reserves top part of
the first bank, and reserves the rest of memory in the follow up banks.

Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
---
Cc: Geert Uytterhoeven <geert at linux-m68k.org>
Cc: Hans Verkuil <hverkuil-cisco at xs4all.nl>
Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
Cc: Kuninori Morimoto <kuninori.morimoto.gx at renesas.com>
Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Cc: Niklas Söderlund <niklas.soderlund at ragnatech.se>
Cc: Simon Glass <sjg at chromium.org>
Cc: Tom Rini <trini at konsulko.com>
Cc: Wolfram Sang <wsa at kernel.org>
---
 boot/image-fdt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/boot/image-fdt.c b/boot/image-fdt.c
index 75bdd55f326..5e4aa9de0d2 100644
--- a/boot/image-fdt.c
+++ b/boot/image-fdt.c
@@ -217,14 +217,14 @@ int boot_relocate_fdt(struct lmb *lmb, char **of_flat_tree, ulong *of_size)
 			if (start + size < low)
 				continue;
 
-			usable = min(size, (u64)mapsize);
+			usable = min(start + size, (u64)(low + mapsize));
 
 			/*
 			 * At least part of this DRAM bank is usable, try
 			 * using it for LMB allocation.
 			 */
 			of_start = map_sysmem((ulong)lmb_alloc_base(lmb,
-				    of_len, 0x1000, start + usable), of_len);
+				    of_len, 0x1000, usable), of_len);
 			/* Allocation succeeded, use this block. */
 			if (of_start != NULL)
 				break;
-- 
2.43.0