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arm: mediatek: mt8195: fix gd->ram_top limit

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Fix the implementation of the gd->ram_top limit for mt8195.

The intention of the comment about MMC/DMA is correct, but the
implementation was wrong. gd->mon_len is set to the code size of U-Boot,
so trying to set it to limit gd->ram_top does not make sense.

Instead, there is already a get_effective_memsize() weak function that
we can override to implement the required limit on the usable memory
size. This is used to set gd->ram_top in setup_dest_addr().

The comment about the extra SZ_1M needing to be reserved is not correct
as U-Boot already takes care of this (with the actual size of U-Boot) in
the various board_f functions, so it is removed.

This fixes DMA not working on MMC on mt8195.

Reviewed-by: Julien Stephan <jstephan@baylibre.com>
Tested-by: Julien Stephan <jstephan@baylibre.com>
Link: https://patch.msgid.link/20260319-mtk-init-fix-dram-v1-12-6171ec141f40@baylibre.com
Signed-off-by: David Lechner <dlechner@baylibre.com>
This commit is contained in:
David Lechner
2026-04-06 18:39:10 -05:00
parent e620d592e8
commit af4cba9a05
1 changed files with 8 additions and 14 deletions
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arch/arm/mach-mediatek/mt8195/init.c
+8 -14
View File
@@ -9,6 +9,7 @@
#include <asm/armv8/mmu.h>
#include <asm/system.h>
#include <dm/uclass.h>
#include <linux/kernel.h>
#include <linux/sizes.h>
#include <wdt.h>
@@ -16,23 +17,16 @@ DECLARE_GLOBAL_DATA_PTR;
int dram_init(void)
{
int ret;
ret = fdtdec_setup_mem_size_base();
if (ret)
return ret;
return fdtdec_setup_mem_size_base();
}
phys_size_t get_effective_memsize(void)
{
/*
* Limit gd->ram_top not exceeding SZ_4G. Some periphals like mmc
* requires DMA buffer allocated below SZ_4G.
*
* Note: SZ_1M is for adjusting gd->relocaddr, the reserved memory for
* u-boot itself.
* Limit gd->ram_top not exceeding SZ_4G. Because some peripherals like
* MMC requires DMA buffer allocated below SZ_4G.
*/
if (gd->ram_base + gd->ram_size >= SZ_4G)
gd->mon_len = (gd->ram_base + gd->ram_size + SZ_1M) - SZ_4G;
return 0;
return min(SZ_4G - gd->ram_base, gd->ram_size);
}
int mtk_soc_early_init(void)