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* [PATCH 1/4] ARM: i.MX6 Wandboard: dont do MMDC Write Leveling Calibration
@ 2017-06-08 18:41 Alexander Kurz
  2017-06-08 18:41 ` [PATCH 2/4] ARM: i.MX6 Wandboard Quad: fix PBL UART MUX Alexander Kurz
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Alexander Kurz @ 2017-06-08 18:41 UTC (permalink / raw)
  To: barebox; +Cc: Alexander Kurz

The hardware requirements to perform a write leveling calibration are
not fulfilled by the Wandboard modules.
IMX6DQRM §44.11.6 "Write leveling Calibration" Note2 states that the first
bit of each data byte group (D0, D8, ..., D56) from memory must be connected
to the same data bus bit on the controller, which is not given on the
Wandboard modules, resulting in unpredictable calib results and breaking the
WBQUAD 2GiB SDRAM setup. Similar restrictions exist for the i.MX6SD.

Remove this calibration and use the MPWLDECTRL defaults.

Signed-off-by: Alexander Kurz <akurz@blala.de>
---
 arch/arm/boards/technexion-wandboard/lowlevel.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm/boards/technexion-wandboard/lowlevel.c b/arch/arm/boards/technexion-wandboard/lowlevel.c
index d3eb9a0..ff5ae6d 100644
--- a/arch/arm/boards/technexion-wandboard/lowlevel.c
+++ b/arch/arm/boards/technexion-wandboard/lowlevel.c
@@ -276,7 +276,6 @@ static unsigned long wandboard_dram_init(void)
 
 	__udelay(100);
 
-	mmdc_do_write_level_calibration();
 	mmdc_do_dqs_calibration();
 #ifdef DEBUG
 	mmdc_print_calibration_results();
-- 
2.1.4


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^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2017-06-13  7:27 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-06-08 18:41 [PATCH 1/4] ARM: i.MX6 Wandboard: dont do MMDC Write Leveling Calibration Alexander Kurz
2017-06-08 18:41 ` [PATCH 2/4] ARM: i.MX6 Wandboard Quad: fix PBL UART MUX Alexander Kurz
2017-06-08 18:55   ` Andrey Smirnov
2017-06-08 18:41 ` [PATCH 3/4] ARM: i.MX6 Wandboard: enable Wandboard Quad Alexander Kurz
2017-06-08 18:41 ` [PATCH 4/4] ARM: i.MX6 Wandboard: add Documentation Alexander Kurz
2017-06-13  7:27 ` [PATCH 1/4] ARM: i.MX6 Wandboard: dont do MMDC Write Leveling Calibration Sascha Hauer

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