video: exynos_dp: increase AUX channel voltage level

The value of AUX channel differential amplitude current is changed
from 8 mA to 16 mA, in order to increase AUX channel voltage level.
In this case, AUX channel voltage level can be changed from 400 mV
to 800 mV, when resistance between AUX TX and RX is 100 ohm.

According to DP spec, although the normative voltage level is 390 mV,
the informative voltage level is 430 mV. So, 800 mV can be helpful
to improve voltage margin of AUX channel.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

diff --git a/drivers/video/exynos/exynos_dp_reg.c b/drivers/video/exynos/exynos_dp_reg.c
index 365be69d9b5cc962cfa70f7b256ab03f28447725..3f5ca8a0d5ea45076d3929decfb514a1d9e5e52c 100644 (file)
--- a/drivers/video/exynos/exynos_dp_reg.c
+++ b/drivers/video/exynos/exynos_dp_reg.c
@@ -77,7 +77,7 @@ void exynos_dp_init_analog_param(struct exynos_dp_device *dp)
        writel(reg, dp->reg_base + EXYNOS_DP_ANALOG_CTL_3);
 
        reg = PD_RING_OSC | AUX_TERMINAL_CTRL_50_OHM |
-               TX_CUR1_2X | TX_CUR_8_MA;
+               TX_CUR1_2X | TX_CUR_16_MA;
        writel(reg, dp->reg_base + EXYNOS_DP_PLL_FILTER_CTL_1);
 
        reg = CH3_AMP_400_MV | CH2_AMP_400_MV |

diff --git a/drivers/video/exynos/exynos_dp_reg.h b/drivers/video/exynos/exynos_dp_reg.h
index 9e9af50d7da34d5797d90fed74e610e166390295..1f2f014cfe88687c323428ba31c1e29c1cac9c2e 100644 (file)
--- a/drivers/video/exynos/exynos_dp_reg.h
+++ b/drivers/video/exynos/exynos_dp_reg.h
@@ -187,7 +187,7 @@
 #define PD_RING_OSC                            (0x1 << 6)
 #define AUX_TERMINAL_CTRL_50_OHM               (0x2 << 4)
 #define TX_CUR1_2X                             (0x1 << 2)
-#define TX_CUR_8_MA                            (0x2 << 0)
+#define TX_CUR_16_MA                           (0x3 << 0)
 
 /* EXYNOS_DP_TX_AMP_TUNING_CTL */
 #define CH3_AMP_400_MV                         (0x0 << 24)