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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> |
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| Kconfig | ||