From af4cba9a05aad97f956b21e8e9060e0307bd9afc Mon Sep 17 00:00:00 2001 From: David Lechner Date: Thu, 19 Mar 2026 15:00:15 -0500 Subject: arm: mediatek: mt8195: fix gd->ram_top limit 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 Tested-by: Julien Stephan Link: https://patch.msgid.link/20260319-mtk-init-fix-dram-v1-12-6171ec141f40@baylibre.com Signed-off-by: David Lechner --- arch/arm/mach-mediatek/mt8195/init.c | 22 ++++++++-------------- 1 file changed, 8 insertions(+), 14 deletions(-) diff --git a/arch/arm/mach-mediatek/mt8195/init.c b/arch/arm/mach-mediatek/mt8195/init.c index 6b47ca4b059..e31d4eec0fb 100644 --- a/arch/arm/mach-mediatek/mt8195/init.c +++ b/arch/arm/mach-mediatek/mt8195/init.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include @@ -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) -- cgit v1.2.3