LD20 / PXs3 boards are equipped with a large amount of memory beyond the 32 bit address range. U-Boot relocates itself to the end of the available RAM.
This is a problem for DMA engines that only support 32 bit physical address, like the SDMA of SDHCI controllers.
In fact, U-Boot does not need to run at the very end of RAM. It is rather troublesome for drivers with DMA engines because U-Boot does not have API like dma_set_mask(), so DMA silently fails, making the driver debugging difficult.
Hide the memory region that exceeds the 32 bit address range. It can be done by simply carving out gd->ram_size. It would also possible to override get_effective_memsize() or to define CONFIG_MAX_MEM_MAPPED, but dram_init() is a good enough place to do this job.
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com ---
arch/arm/mach-uniphier/dram_init.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/arch/arm/mach-uniphier/dram_init.c b/arch/arm/mach-uniphier/dram_init.c index e9672d2..cb35dab 100644 --- a/arch/arm/mach-uniphier/dram_init.c +++ b/arch/arm/mach-uniphier/dram_init.c @@ -205,6 +205,7 @@ int dram_init(void) return ret;
for (i = 0; i < ARRAY_SIZE(dram_map); i++) { + unsigned long max_size;
if (!dram_map[i].size) break; @@ -218,6 +219,22 @@ int dram_init(void) dram_map[i].base) break;
+ /* + * Do not use memory that exceeds 32bit address range. U-Boot + * relocates itself to the end of the effectively available RAM. + * This could be a problem for DMA engines that do not support + * 64bit address (SDMA of SDHCI, UniPhier AV-ether, etc.) + */ + if (dram_map[i].base >= 1ULL << 32) + break; + + max_size = (1ULL << 32) - dram_map[i].base; + + if (dram_map[i].size > max_size) { + gd->ram_size += max_size; + break; + } + gd->ram_size += dram_map[i].size; }