[U-Boot] [PATCH 3/3] sunxi: dram: Allow to configure vdd-dll voltage on sun[457]i

[Siarhei Siamashka]

Higher vdd-dll voltage allows to use higher dram and mbus clock speeds.
The vdd-int/vdd-dll voltage is currently set to 1.25V by default, which
is much lower than 1.4V, allowed by datasheets (the exact maximum differs
for different SoCs).

There are different use cases. For a tablet, it may be preferable to
favor longer battery life and use lower dram clock speed & voltage.
But for non-battery powered devices, especially the ones driving full-hd
monitors, memory performance may be a lot more important than the power
consumption.

A configurable vdd-dll voltage provides better flexibility.

Signed-off-by: Siarhei Siamashka <siarhei.siamashka at gmail.com>
---
 arch/arm/include/asm/arch-sunxi/dram.h       |  1 +
 arch/arm/include/asm/arch-sunxi/dram_sun4i.h |  1 +
 board/sunxi/Kconfig                          |  8 ++++++++
 board/sunxi/board.c                          | 10 +++++++++-
 board/sunxi/dram_sun4i_auto.c                |  6 ++++++
 board/sunxi/dram_sun5i_auto.c                |  7 +++++++
 6 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/arch-sunxi/dram.h b/arch/arm/include/asm/arch-sunxi/dram.h
index 7ff43e6..61ed77c 100644
--- a/arch/arm/include/asm/arch-sunxi/dram.h
+++ b/arch/arm/include/asm/arch-sunxi/dram.h
@@ -25,6 +25,7 @@
 #endif
 
 unsigned long sunxi_dram_init(void);
+u32 sunxi_dram_get_min_dll_volt(void);
 
 /*
  * Wait up to 1s for value to be set in given part of reg.
diff --git a/arch/arm/include/asm/arch-sunxi/dram_sun4i.h b/arch/arm/include/asm/arch-sunxi/dram_sun4i.h
index 40c385a..32493cc 100644
--- a/arch/arm/include/asm/arch-sunxi/dram_sun4i.h
+++ b/arch/arm/include/asm/arch-sunxi/dram_sun4i.h
@@ -88,6 +88,7 @@ struct dram_para {
 	u32 emr3;
 	u32 dqs_gating_delay;
 	u32 active_windowing;
+	u32 min_dll_volt;
 };
 
 #define DRAM_CCR_COMMAND_RATE_1T (0x1 << 5)
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index 4a21589..3092edc 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -99,6 +99,14 @@ config DRAM_DQS_GATING_DELAY
 	is usually good enough, unless running at really high DRAM
 	clocks speeds (up to 600MHz). If unsure, keep as 0.
 
+config DRAM_MIN_DLL_VOLT
+	int "sunxi dram odt_en value"
+	default 1250
+	---help---
+	Set the minimum VDD-DLL/VDD-INT voltage (mV), required for
+	reliable DRAM operation. On Allwinner A10/A13/A20 devices with
+	AXP209 PMIC it is provided from DCDC3.
+
 choice
 	prompt "sunxi dram timings"
 	default DRAM_TIMINGS_VENDOR_MAGIC
diff --git a/board/sunxi/board.c b/board/sunxi/board.c
index b70e00c..ce6aef5 100644
--- a/board/sunxi/board.c
+++ b/board/sunxi/board.c
@@ -154,11 +154,19 @@ void i2c_init_board(void)
 	clock_twi_onoff(0, 1);
 }
 
+__weak u32 sunxi_dram_get_min_dll_volt(void)
+{
+	return 0;
+}
+
 #ifdef CONFIG_SPL_BUILD
 void sunxi_board_init(void)
 {
 	int power_failed = 0;
 	unsigned long ramsize;
+	u32 min_dll_volt = sunxi_dram_get_min_dll_volt();
+	if (min_dll_volt < 1250)
+		min_dll_volt = 1250;
 
 #ifdef CONFIG_AXP152_POWER
 	power_failed = axp152_init();
@@ -170,7 +178,7 @@ void sunxi_board_init(void)
 #ifdef CONFIG_AXP209_POWER
 	power_failed |= axp209_init();
 	power_failed |= axp209_set_dcdc2(1400);
-	power_failed |= axp209_set_dcdc3(1250);
+	power_failed |= axp209_set_dcdc3(min_dll_volt);
 	power_failed |= axp209_set_ldo2(3000);
 	power_failed |= axp209_set_ldo3(2800);
 	power_failed |= axp209_set_ldo4(2800);
diff --git a/board/sunxi/dram_sun4i_auto.c b/board/sunxi/dram_sun4i_auto.c
index 09e0c9a..c0c8a28 100644
--- a/board/sunxi/dram_sun4i_auto.c
+++ b/board/sunxi/dram_sun4i_auto.c
@@ -27,9 +27,15 @@ static struct dram_para dram_para = {
 	.emr1 = CONFIG_DRAM_EMR1,
 	.emr3 = 0,
 	.dqs_gating_delay = CONFIG_DRAM_DQS_GATING_DELAY,
+	.min_dll_volt = CONFIG_DRAM_MIN_DLL_VOLT,
 };
 
 unsigned long sunxi_dram_init(void)
 {
 	return dramc_init(&dram_para);
 }
+
+u32 sunxi_dram_get_min_dll_volt(void)
+{
+	return dram_para.min_dll_volt;
+}
diff --git a/board/sunxi/dram_sun5i_auto.c b/board/sunxi/dram_sun5i_auto.c
index e52d54c..30febe5 100644
--- a/board/sunxi/dram_sun5i_auto.c
+++ b/board/sunxi/dram_sun5i_auto.c
@@ -30,9 +30,16 @@ static struct dram_para dram_para = {
 	.emr1 = CONFIG_DRAM_EMR1,
 	.emr3 = 0,
 	.dqs_gating_delay = CONFIG_DRAM_DQS_GATING_DELAY,
+	.min_dll_volt = CONFIG_DRAM_MIN_DLL_VOLT,
 };
 
 unsigned long sunxi_dram_init(void)
 {
 	return dramc_init(&dram_para);
 }
+
+
+u32 sunxi_dram_get_min_dll_volt(void)
+{
+	return dram_para.min_dll_volt;
+}
-- 
2.0.5