[PATCH 3/7] arm: mediatek: mt7988: fix gd->bd->bi_dram[0].size

[David Lechner]

Use board_get_usable_ram_top() instead of get_effective_memsize() to
set gd->ram_top to something <= 4GiB.

Both board_get_usable_ram_top() and get_effective_memsize() are used to
set gd->ram_top in setup_dest_addr(). However, get_effective_memsize()
also sets gd->bd->bi_dram[0].size in dram_init_banksize(), which is
undesirable.

Prior to commit bddd6bbef3dc ("arm: mediatek: mt7988:
drop dram_init_banksize()"), gd->bd->bi_dram[0].size was overridden in
a board-specific dram_init_banksize() implementation. When that was
removed get_effective_memsize() set gd->bd->bi_dram[0].size to the wrong
value because of CFG_MAX_MEM_MAPPED.

Rather than continue to use an old-style CFG_ option and the potentially
confusing overriding of gd->bd->bi_dram[0].size (it is difficult to see
which order the functions that set it are called), we can just use
board_get_usable_ram_top() to set gd->ram_top to the correct value
instead. This is possible now, thanks to LMB_LIMIT_DMA_BELOW_RAM_TOP
being set by default for 64-bit Mediatek ARM SoCs.

The CFG_MAX_MEM_MAPPED option is removed since it is no longer needed.
The config header and Kconfig option are also removed since that was
the last CFG_ option.

Reported-by: Rudy Andram <rmandrad at gmail.com>
Closes: https://lore.kernel.org/u-boot/20260602162233.2418471-1-rmandrad@gmail.com/
Fixes: bddd6bbef3dc ("arm: mediatek: mt7988: drop dram_init_banksize()")
Signed-off-by: David Lechner <dlechner at baylibre.com>
---
 arch/arm/mach-mediatek/Kconfig       |  1 -
 arch/arm/mach-mediatek/mt7988/init.c | 10 ++++++++++
 board/mediatek/mt7988/MAINTAINERS    |  1 -
 include/configs/mt7988.h             | 14 --------------
 4 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/arch/arm/mach-mediatek/Kconfig b/arch/arm/mach-mediatek/Kconfig
index 054b1bf92bf..799c630fed3 100644
--- a/arch/arm/mach-mediatek/Kconfig
+++ b/arch/arm/mach-mediatek/Kconfig
@@ -199,7 +199,6 @@ config SYS_CONFIG_NAME
 	default "mt7629" if TARGET_MT7629
 	default "mt7981" if TARGET_MT7981
 	default "mt7986" if TARGET_MT7986
-	default "mt7988" if TARGET_MT7988
 	default "mt8183" if TARGET_MT8183
 	default "mt8512" if TARGET_MT8512
 	default "mt8516" if TARGET_MT8516
diff --git a/arch/arm/mach-mediatek/mt7988/init.c b/arch/arm/mach-mediatek/mt7988/init.c
index 7f4d934bfe9..5b37a91cd72 100644
--- a/arch/arm/mach-mediatek/mt7988/init.c
+++ b/arch/arm/mach-mediatek/mt7988/init.c
@@ -6,6 +6,7 @@
 
 #include <fdtdec.h>
 #include <init.h>
+#include <linux/kernel.h>
 #include <linux/sizes.h>
 #include <asm/armv8/mmu.h>
 #include <asm/global_data.h>
@@ -26,6 +27,15 @@ int dram_init(void)
 	return 0;
 }
 
+phys_addr_t board_get_usable_ram_top(phys_size_t total_size)
+{
+	/*
+	 * Limit gd->ram_top not exceeding SZ_4G. Because some peripherals like
+	 * MMC requires DMA buffer allocated below SZ_4G.
+	 */
+	return min(gd->ram_top, SZ_4G);
+}
+
 void reset_cpu(ulong addr)
 {
 	psci_system_reset();
diff --git a/board/mediatek/mt7988/MAINTAINERS b/board/mediatek/mt7988/MAINTAINERS
index a45bfff26ca..c7e30342e5c 100644
--- a/board/mediatek/mt7988/MAINTAINERS
+++ b/board/mediatek/mt7988/MAINTAINERS
@@ -2,6 +2,5 @@ MT7988
 M:	Sam Shih <sam.shih at mediatek.com>
 S:	Maintained
 F:	board/mediatek/mt7988
-F:	include/configs/mt7988.h
 F:	configs/mt7988_rfb_defconfig
 F:	configs/mt7988_sd_rfb_defconfig
diff --git a/include/configs/mt7988.h b/include/configs/mt7988.h
deleted file mode 100644
index e63825a5a19..00000000000
--- a/include/configs/mt7988.h
+++ /dev/null
@@ -1,14 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Configuration for MediaTek MT7988 SoC
- *
- * Copyright (C) 2022 MediaTek Inc.
- * Author: Sam Shih <sam.shih at mediatek.com>
- */
-
-#ifndef __MT7988_H
-#define __MT7988_H
-
-#define CFG_MAX_MEM_MAPPED		0xC0000000
-
-#endif

-- 
2.43.0