[U-Boot] [PATCH 1/2] am33xx,ddr3: fix ddr3 sdram configuration

[U-Boot] [PATCH 1/2] am33xx,ddr3: fix ddr3 sdram configuration

[Samuel Egli]

This patch fixes the DDR3 initialization procedure in
order to comply with DDR3 standard. A 500 us delay is specified
between the DDR3 reset and clock enable signal. Until now,
this delay was not respected. Some DDR3 chips don't bother
but the bigger the RAM becomes the more likely it seems that
this delay is needed. We observed that DRAM > 256 MB from
the manufacturer Samsung have an issue when the specification
is not respected.

Changes:

1) Add a 1 ms wait for L3 timeout error trigger

2) Don't delay DDR3 initialization
Bit 31 of emif_sdram_ref_ctrl shouldn't be set because his
suppresses the initialization of DDR3

Signed-off-by: Samuel Egli <samuel.egli@siemens.com>
Reviewed-by: James Doublesin <doublesin@ti.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Roger Meier <r.meier@siemens.com>
Cc: Heiko Schocher <hs@denx.de>
---
 arch/arm/cpu/armv7/am33xx/ddr.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/arm/cpu/armv7/am33xx/ddr.c b/arch/arm/cpu/armv7/am33xx/ddr.c
index b3fb0c4..888cf1f 100644
--- a/arch/arm/cpu/armv7/am33xx/ddr.c
+++ b/arch/arm/cpu/armv7/am33xx/ddr.c
@@ -164,6 +164,13 @@ void config_sdram(const struct emif_regs *regs, int nr)
 		writel(regs->zq_config, &emif_reg[nr]->emif_zq_config);
 		writel(regs->sdram_config, &cstat->secure_emif_sdram_config);
 		writel(regs->sdram_config, &emif_reg[nr]->emif_sdram_config);
+
+		/* Trigger initialization */
+		writel(0x00003100, &emif_reg[nr]->emif_sdram_ref_ctrl);
+		/* Wait 1ms because of L3 timeout error */
+		udelay(1000);
+
+		/* Write proper sdram_ref_cref_ctrl value */
 		writel(regs->ref_ctrl, &emif_reg[nr]->emif_sdram_ref_ctrl);
 		writel(regs->ref_ctrl, &emif_reg[nr]->emif_sdram_ref_ctrl_shdw);
 	}
@@ -292,7 +299,9 @@ void config_ddr_phy(const struct emif_regs *regs, int nr)
 		     EMIF_REG_INITREF_DIS_MASK);
 #endif
 	if (regs->zq_config)
-		writel(0x80003100, &emif_reg[nr]->emif_sdram_ref_ctrl);
+		/* Set time between rising edge of DDR_RESET to rising
+		 * edge of DDR_CKE to > 500us per memory spec. */
+		writel(0x00003100, &emif_reg[nr]->emif_sdram_ref_ctrl);
 
 	writel(regs->emif_ddr_phy_ctlr_1,
 		&emif_reg[nr]->emif_ddr_phy_ctrl_1);
-- 
2.1.4

[U-Boot] [PATCH 2/2] siemens,am33x: remove ddr3 delay workaround

[Samuel Egli]

Signed-off-by: Samuel Egli <samuel.egli@siemens.com>
Cc: Roger Meier <r.meier@siemens.com>
Cc: Heiko Schocher <hs@denx.de>
---
 board/siemens/draco/board.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/board/siemens/draco/board.c b/board/siemens/draco/board.c
index 4882314..988c12a 100644
--- a/board/siemens/draco/board.c
+++ b/board/siemens/draco/board.c
@@ -196,11 +196,6 @@ struct ctrl_ioregs draco_ddr3_ioregs = {
 
 	config_ddr(DDR_PLL_FREQ, &draco_ddr3_ioregs, &draco_ddr3_data,
 		   &draco_ddr3_cmd_ctrl_data, &draco_ddr3_emif_reg_data, 0);
-
-	/* For Samsung 2Gbit RAM we need this delay otherwise config fails after
-	 * soft reset.
-	 */
-	udelay(2000);
 }
 
 static void spl_siemens_board_init(void)
-- 
2.1.4

[U-Boot] [U-Boot, 1/2] am33xx, ddr3: fix ddr3 sdram configuration

[Tom Rini]

On Wed, Dec 02, 2015 at 03:27:56PM +0100, Egli, Samuel wrote:

> This patch fixes the DDR3 initialization procedure in
> order to comply with DDR3 standard. A 500 us delay is specified
> between the DDR3 reset and clock enable signal. Until now,
> this delay was not respected. Some DDR3 chips don't bother
> but the bigger the RAM becomes the more likely it seems that
> this delay is needed. We observed that DRAM > 256 MB from
> the manufacturer Samsung have an issue when the specification
> is not respected.
> 
> Changes:
> 
> 1) Add a 1 ms wait for L3 timeout error trigger
> 
> 2) Don't delay DDR3 initialization
> Bit 31 of emif_sdram_ref_ctrl shouldn't be set because his
> suppresses the initialization of DDR3
> 
> Signed-off-by: Samuel Egli <samuel.egli@siemens.com>
> Reviewed-by: James Doublesin <doublesin@ti.com>
> Cc: Tom Rini <trini@konsulko.com>
> Cc: Felipe Balbi <balbi@ti.com>
> Cc: Roger Meier <r.meier@siemens.com>
> Cc: Heiko Schocher <hs@denx.de>

Applied to u-boot/master, thanks!

-- 
Tom
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[U-Boot] [U-Boot, 2/2] siemens, am33x: remove ddr3 delay workaround

[Tom Rini]

On Wed, Dec 02, 2015 at 03:27:57PM +0100, Egli, Samuel wrote:

> Signed-off-by: Samuel Egli <samuel.egli@siemens.com>
> Cc: Roger Meier <r.meier@siemens.com>
> Cc: Heiko Schocher <hs@denx.de>

Applied to u-boot/master, thanks!

-- 
Tom
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