[PATCH] board_f: show_dram_config: Print also real DRAM size

[Pali Rohár]

32-bit U-Boot builds cannot use more than around 2 GB of DDR memory. But on
some platforms/boards it is possible to connect also 4 GB SODIMM DDR memory.
U-Boot currently prints only effective size of RAM which can use, which may
be misleading as somebody would expect that this line prints total size of
connected DDR modules. So change show_dram_config code to prints both real
and effective DRAM size if they are different. If they are same then print
just one number like before. It is possible that effective size is just few
bytes smaller than the real size, so print both numbers only in case
function print_size() prints formats them differently.

Signed-off-by: Pali Rohár <pali at kernel.org>
---
 common/board_f.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/common/board_f.c b/common/board_f.c
index 9e34fbee147e..3131a06db940 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -54,6 +54,7 @@
 #include <asm/sections.h>
 #include <dm/root.h>
 #include <linux/errno.h>
+#include <linux/log2.h>
 
 /*
  * Pointer to initial global data area
@@ -213,6 +214,30 @@ static int announce_dram_init(void)
 	return 0;
 }
 
+/*
+ * Check if the sizes in their natural units written in decimal format with
+ * one fraction number are same.
+ */
+static int sizes_near(unsigned long long size1, unsigned long long size2)
+{
+	unsigned int size1_scale = ilog2(size1) / 10 * 10;
+	unsigned int size1_val = (10 * size1 + ((1ULL << size1_scale) >> 1)) >> size1_scale;
+	unsigned int size2_scale = ilog2(size2) / 10 * 10;
+	unsigned int size2_val = (10 * size2 + ((1ULL << size2_scale) >> 1)) >> size2_scale;
+
+	if (size1_val == 10240) {
+		size1_val = 10;
+		size1_scale += 10;
+	}
+
+	if (size2_val == 10240) {
+		size2_val = 10;
+		size2_scale += 10;
+	}
+
+	return size1_scale == size2_scale && size1_val == size2_val;
+}
+
 static int show_dram_config(void)
 {
 	unsigned long long size;
@@ -229,7 +254,11 @@ static int show_dram_config(void)
 	}
 	debug("\nDRAM:  ");
 
-	print_size(size, "");
+	print_size(gd->ram_size, "");
+	if (!sizes_near(gd->ram_size, size)) {
+		printf(" (effective ");
+		print_size(size, ")");
+	}
 	board_add_ram_info(0);
 	putc('\n');
 
-- 
2.20.1