rpi: Fix DRAM size reporting to show total RAM

The VideoCore mailbox GET_ARM_MEMORY only reports the size of the
first accessible memory region (~947 MiB on RPi4 with 8GB), not the
total RAM. This causes U-Boot to display "DRAM: 947 MiB (total 7.9 GiB)"
instead of "DRAM: 7.9 GiB".

On Raspberry Pi 4 with 8GB RAM, the memory is split across multiple
non-contiguous banks. The dram_init() function only sets gd->ram_size
to the first bank size reported by the VideoCore firmware, while
fdtdec_setup_memory_banksize() correctly populates all memory banks
from the device tree.

Fix this by updating gd->ram_size after dram_init_banksize() has
populated all memory banks, so it reflects the actual total RAM
across all banks.

Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Reviewed-by: Peter Robinson <pbrobinson@gmail.com>

diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c
index 6f96c1e..f9b6435 100644 (file)
--- a/board/raspberrypi/rpi/rpi.c
+++ b/board/raspberrypi/rpi/rpi.c
@@ -334,13 +334,27 @@ int dram_init(void)
 #ifdef CONFIG_OF_BOARD
 int dram_init_banksize(void)
 {
+       phys_addr_t total_size = 0;
+       int i;
        int ret;
 
        ret = fdtdec_setup_memory_banksize();
        if (ret)
                return ret;
 
-       return fdtdec_setup_mem_size_base();
+       ret = fdtdec_setup_mem_size_base();
+       if (ret)
+               return ret;
+
+       /* Update gd->ram_size to reflect total RAM across all banks */
+       for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
+               if (gd->bd->bi_dram[i].size == 0)
+                       break;
+               total_size += gd->bd->bi_dram[i].size;
+       }
+       gd->ram_size = total_size;
+
+       return 0;
 }
 #endif