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From: Alexander Kurz <akurz@blala.de>
To: barebox@lists.infradead.org
Cc: Alexander Kurz <akurz@blala.de>
Subject: [PATCH 1/4] ARM: i.MX6 Wandboard: dont do MMDC Write Leveling Calibration
Date: Thu,  8 Jun 2017 20:41:34 +0200	[thread overview]
Message-ID: <1496947297-23502-1-git-send-email-akurz@blala.de> (raw)

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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             reply	other threads:[~2017-06-08 18:43 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-08 18:41 Alexander Kurz [this message]
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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