Hi,
On 18-12-14 20:12, Ian Campbell wrote:
On Tue, 2014-12-16 at 21:31 +0100, Hans de Goede wrote:
The sun8i boot0 code fills the DRAM with a "random" pattern before comparing
it at different offsets to do columns, etc. detection. The sun6i boot0 code
does not do it, but it seems like a good idea to do this regardless.
Is this the right way round?
Yes, while working on the sun8i code I noticed that it was prefilling memory
before doing wrap-around checks like the sun6i code is doing too, and then I
realized that the sun6i code was relying on whatever is in DRAM being random
enough for its wrap-around tests to work, without ensuring it is random
enough.
The existing sun6i code (which you are
moving here) seems to _rely_ on something having written a useful
pattern, which I would have assumed to have been boot0. Or else how does
it work now? Chance?
Yep, it purely works by chance so far.
Regards,
Hans
The new mctl_mem_fill function this introduces is added as an inline helper
in dram.h, so that it can be shared with the sun8i dram code.
While at it move mctl_mem_matches to dram.h for re-use in sun8i too.
Signed-off-by: Hans de Goede <hdego...@redhat.com>
---
arch/arm/cpu/armv7/sunxi/dram_sun6i.c | 15 +--------------
arch/arm/include/asm/arch-sunxi/dram.h | 29 +++++++++++++++++++++++++++++
2 files changed, 30 insertions(+), 14 deletions(-)
diff --git a/arch/arm/cpu/armv7/sunxi/dram_sun6i.c
b/arch/arm/cpu/armv7/sunxi/dram_sun6i.c
index e1670e5..4675c48 100644
--- a/arch/arm/cpu/armv7/sunxi/dram_sun6i.c
+++ b/arch/arm/cpu/armv7/sunxi/dram_sun6i.c
@@ -326,20 +326,6 @@ static void mctl_port_cfg(void)
writel(0x00000307, &mctl_com->mbagcr[5]);
}
-static bool mctl_mem_matches(u32 offset)
-{
- const int match_count = 64;
- int i, matches = 0;
-
- for (i = 0; i < match_count; i++) {
- if (readl(CONFIG_SYS_SDRAM_BASE + i * 4) ==
- readl(CONFIG_SYS_SDRAM_BASE + offset + i * 4))
- matches++;
- }
-
- return matches == match_count;
-}
-
unsigned long sunxi_dram_init(void)
{
struct sunxi_mctl_com_reg * const mctl_com =
@@ -391,6 +377,7 @@ unsigned long sunxi_dram_init(void)
MCTL_CR_BANK(1) | MCTL_CR_RANK(1));
/* Detect and set page size */
+ mctl_mem_fill();
for (columns = 7; columns < 20; columns++) {
if (mctl_mem_matches(1 << columns))
break;
diff --git a/arch/arm/include/asm/arch-sunxi/dram.h
b/arch/arm/include/asm/arch-sunxi/dram.h
index 18924f5..0bf718c 100644
--- a/arch/arm/include/asm/arch-sunxi/dram.h
+++ b/arch/arm/include/asm/arch-sunxi/dram.h
@@ -22,6 +22,8 @@
#include <asm/arch/dram_sun4i.h>
#endif
+#define MCTL_MEM_FILL_MATCH_COUNT 64
+
unsigned long sunxi_dram_init(void);
/*
@@ -37,4 +39,31 @@ static inline void mctl_await_completion(u32 *reg, u32 mask,
u32 val)
}
}
+/*
+ * Fill beginning of DRAM with "random" data for mctl_mem_matches()
+ */
+static inline void mctl_mem_fill(void)
+{
+ int i;
+
+ for (i = 0; i < MCTL_MEM_FILL_MATCH_COUNT; i++)
+ writel(0xaa55aa55 + i, CONFIG_SYS_SDRAM_BASE + i * 4);
+}
+
+/*
+ * Test if memory at offset offset matches memory at begin of DRAM
+ */
+static inline bool mctl_mem_matches(u32 offset)
+{
+ int i, matches = 0;
+
+ for (i = 0; i < MCTL_MEM_FILL_MATCH_COUNT; i++) {
+ if (readl(CONFIG_SYS_SDRAM_BASE + i * 4) ==
+ readl(CONFIG_SYS_SDRAM_BASE + offset + i * 4))
+ matches++;
+ }
+
+ return matches == MCTL_MEM_FILL_MATCH_COUNT;
+}
+
#endif /* _SUNXI_DRAM_H */
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