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ddr: marvell: a38x: fix BYTE_HOMOGENEOUS_SPLIT_OUT decision

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In commit 3fc92a215b ("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>
This commit is contained in:
Marek Behún 2022-02-17 01:08:37 +01:00 committed by Stefan Roese
parent 18ab060288
commit a163db9fba
1 changed files with 4 additions and 2 deletions
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6
drivers/ddr/marvell/a38x/ddr3_training_centralization.c
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@ -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,