Patch set updated for coreboot: bb30380 Exynos5250: make vendor enums in the timing array more debuggable.

[Ronald G. Minnich]

Ronald G. Minnich ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/2221

-gerrit

commit bb303803b3e7fa10a901e1fb91a98f3c2ec1c0dc
Author: Ronald G. Minnich 
Date:   Tue Jan 29 11:52:05 2013 -0800

Exynos5250: make vendor enums in the timing array more debuggable.

The timing array is crucial to proper operation of DRAM.

Getting a valid pointer to it is hence very important. Unfortunately,
    the constants chosen for the vendor were '1', and '2', (this in a
    32-bit word) which in a debug print makes it almost impossible to tell
    if you've got a misaligned pointer. Note: coreboot people did not
    choose them :-)

So, give them values which are extremely unlikely to occur elsewhere
    in the array (or in memory, for that matter).

Given the frequency with which this check occurs, i.e. once, I would
    much prefer strings but I expect I'd get shouted down on that
    one. Constants in this case are an almost useless optimization but
    we'll go with them for now. Note no space is saved by not using
    strings: there's an entire function somewhere devoted to mapping the
    enum to a string!

Debug prints of pointers to structs in this array are now far more
    useful than they were.

See snarky comment in the code (left there to make sure nobody gets
    tempted to get fancy again). Comment now less snarky.

This is tested on google snow to the point that the DRAM works.

Change-Id: I30bc44719f321f791fd82ded60e29393399d9e3d
    Signed-off-by: Ronald G. Minnich 
---
 src/cpu/samsung/exynos5250/dmc.h | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/cpu/samsung/exynos5250/dmc.h b/src/cpu/samsung/exynos5250/dmc.h
index d1dfbb1..b778e09 100644
--- a/src/cpu/samsung/exynos5250/dmc.h
+++ b/src/cpu/samsung/exynos5250/dmc.h
@@ -152,12 +152,27 @@ enum ddr_mode {
    DDR_MODE_COUNT,
 };

+/* For reasons unknown, people are in the habit of taking a 32-bit
+ * field with 2 possible values and packing it with, say, 2 bits. A
+ * non-robust encoding, using only 2 bits of a 32-bit field, is
+ * incredibly difficult to deal with when things go wrong, because
+ * there are a lot of things that get expressed as 0, 1, or 2. If
+ * you're scanning with jtag or dumping memory it is really hard to
+ * tell when you've hit the beginning of the struct. So, let's be a
+ * bit smart here. First, while it's common to let the enum count
+ * entries for you, when there are two of them, we can do the
+ * counting. And, let's set the values to something we can easily scan
+ * for in memory. Since '1' and '2' are rather common, we pick
+ * something that's actually of some value when things go wrong.  This
+ * setup motivated by a use case: something's going wrong and having a
+ * manuf name of '1' or '2' is completely useless!
+ */
 enum mem_manuf {
    MEM_MANUF_AUTODETECT,
-	MEM_MANUF_ELPIDA,
-	MEM_MANUF_SAMSUNG,
+	MEM_MANUF_ELPIDA = 0xe7b1da,
+	MEM_MANUF_SAMSUNG = 0x5a5096,

-	MEM_MANUF_COUNT,
+	MEM_MANUF_COUNT = 2, // fancy that.
 };

/* CONCONTROL register fields */