stm32mp: dram_init: Limit DDR usage under 4GB boundary for STM32MP

Limit DDR usage under 4GB boundary on STM32MP regardless of
memory size declared in device tree.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

diff --git a/arch/arm/mach-stm32mp/dram_init.c b/arch/arm/mach-stm32mp/dram_init.c
index cb35ed60ca193fa11f1f9cddd7a96f2eff89eec9..fb1208fc5d570bb3e4676c308bf67f56c57f626f 100644 (file)
--- a/arch/arm/mach-stm32mp/dram_init.c
+++ b/arch/arm/mach-stm32mp/dram_init.c
@@ -52,9 +52,15 @@ phys_addr_t board_get_usable_ram_top(phys_size_t total_size)
        if (!total_size)
                return gd->ram_top;
 
+       /*
+        * make sure U-Boot uses address space below 4GB boundaries even
+        * if the effective available memory is bigger
+        */
+       gd->ram_top = clamp_val(gd->ram_top, 0, SZ_4G - 1);
+
        /* found enough not-reserved memory to relocated U-Boot */
        lmb_init(&lmb);
-       lmb_add(&lmb, gd->ram_base, get_effective_memsize());
+       lmb_add(&lmb, gd->ram_base, gd->ram_top - gd->ram_base);
        boot_fdt_add_mem_rsv_regions(&lmb, (void *)gd->fdt_blob);
        /* add 8M for reserved memory for display, fdt, gd,... */
        size = ALIGN(SZ_8M + CONFIG_SYS_MALLOC_LEN + total_size, MMU_SECTION_SIZE),