[PATCH] arm: mvebu: a38x: Configurable USB2 high-speed impedance threshold

[Joshua Scott]

Hardware testing of a board using the Armada 385 has shown that an
impedance threshold setting of 0x7 performs better in an eye-diagram
test than with Marvell's recommended value 0x6.

As other boards may still perform better with Marvell's reccomended value,
a configuration option is added with a default value of 0x6.

Signed-off-by: Joshua Scott <joshua.scott at alliedtelesis.co.nz>
Cc: Stefan Roese <sr at denx.de.in>
---
 arch/arm/mach-mvebu/Kconfig                           | 5 +++++
 arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c | 6 +++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-mvebu/Kconfig b/arch/arm/mach-mvebu/Kconfig
index 0d8e0922a2..bec011e584 100644
--- a/arch/arm/mach-mvebu/Kconfig
+++ b/arch/arm/mach-mvebu/Kconfig
@@ -30,6 +30,11 @@ config ARMADA_38X
 	select ARMADA_32BIT
 	select HAVE_MVEBU_EFUSE
 
+config ARMADA_38X_HS_IMPEDANCE_THRESH
+	hex  "Armada 38x USB 2.0 High-Speed Impedance Threshold (0x0 - 0x7)"
+	depends on ARMADA_38X
+	default 0x6
+
 config ARMADA_XP
 	bool
 	select ARMADA_32BIT
diff --git a/arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c b/arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c
index 2454730e6d..ae2a361104 100644
--- a/arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c
+++ b/arch/arm/mach-mvebu/serdes/a38x/high_speed_env_spec.c
@@ -677,9 +677,9 @@ struct op_params usb2_power_up_params[] = {
 	{0xc200c, 0x0 /*NA*/, 0xf000, {0x1000}, 0, 0},
 	{0xc400c, 0x0 /*NA*/, 0xf000, {0x1000}, 0, 0},
 	/* Change the High speed impedance threshold */
-	{0xc0008, 0x0 /*NA*/, 0x700, {0x600}, 0, 0},
-	{0xc2008, 0x0 /*NA*/, 0x700, {0x600}, 0, 0},
-	{0xc4008, 0x0 /*NA*/, 0x700, {0x600}, 0, 0},
+	{0xc0008, 0x0 /*NA*/, 0x700, {CONFIG_ARMADA_38X_HS_IMPEDANCE_THRESH << 8}, 0, 0},
+	{0xc2008, 0x0 /*NA*/, 0x700, {CONFIG_ARMADA_38X_HS_IMPEDANCE_THRESH << 8}, 0, 0},
+	{0xc4008, 0x0 /*NA*/, 0x700, {CONFIG_ARMADA_38X_HS_IMPEDANCE_THRESH << 8}, 0, 0},
 	/* Change the squelch level of the receiver to meet the receiver electrical measurements (squelch and receiver sensitivity tests) */
 	{0xc0014, 0x0 /*NA*/, 0xf, {0x8}, 0, 0},
 	{0xc2014, 0x0 /*NA*/, 0xf, {0x8}, 0, 0},
-- 
2.29.2