ddr: marvell: a38x: fix BYTE_HOMOGENEOUS_SPLIT_OUT decision

In commit 3fc92a215b69 ("ddr: marvell: a38x: fix SPLIT_OUT_MIX state
decision") I ported a cleaned up and changed version of patch
  mv_ddr: a380: fix SPLIT_OUT_MIX state decision

In the port we removed checking for BYTE_HOMOGENEOUS_SPLIT_OUT bit,
because:
- the fix seemed to work without it
- the bit was checked for only at one place out of two, while the second
  bit, BYTE_SPLIT_OUT_MIX, was checked for in both cases
- without the removal it didn't work on Allied Telesis' x530 board

We recently had a chance to test on more boards, and it seems that the
change needs to be opposite: instead of removing the check for
BYTE_HOMOGENEOUS_SPLIT_OUT from the first if() statement, the check
needs to be added also to the second one - it needs to be at both
places.

With this change all the Turris Omnia boards I have had available to
test seem to work, I didn't encounter not even one failed DDR training.

As last time, I am noting that I do not understand what this code is
actually doing, I haven't studied the DDR training algorithm and
I suspect that no one will be able to explain it to U-Boot contributors,
so we are left with this blind poking in the code with testing whether
it works on several boards and hoping it doesn't break anything for
anyone :-(.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Tested-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>

diff --git a/drivers/ddr/marvell/a38x/ddr3_training_centralization.c b/drivers/ddr/marvell/a38x/ddr3_training_centralization.c
index 42308b6965dfbae7a0d0532006dfc824f5c8a789..be9f985f22f12428ce8a8135256284d7cae435f7 100644 (file)
--- a/drivers/ddr/marvell/a38x/ddr3_training_centralization.c
+++ b/drivers/ddr/marvell/a38x/ddr3_training_centralization.c
@@ -180,7 +180,8 @@ static int ddr3_tip_centralization(u32 dev_num, u32 mode)
                                                               [bit_id],
                                                               EDGE_1);
                                        if (current_byte_status &
-                                           BYTE_SPLIT_OUT_MIX) {
+                                           (BYTE_SPLIT_OUT_MIX |
+                                            BYTE_HOMOGENEOUS_SPLIT_OUT)) {
                                                if (cur_start_win[bit_id] >= 64)
                                                        cur_start_win[bit_id] -= 64;
                                                else
@@ -197,7 +198,8 @@ static int ddr3_tip_centralization(u32 dev_num, u32 mode)
                                                               EDGE_1);
                                        if (cur_end_win[bit_id] >= 64 &&
                                            (current_byte_status &
-                                            BYTE_SPLIT_OUT_MIX)) {
+                                            (BYTE_SPLIT_OUT_MIX |
+                                             BYTE_HOMOGENEOUS_SPLIT_OUT))) {
                                                cur_end_win[bit_id] -= 64;
                                                DEBUG_CENTRALIZATION_ENGINE
                                                        (DEBUG_LEVEL_INFO,