According to DP 1.4 standard, if the source supports four pre-emphasis levels, then the source shall set the bit MAX_PRE-EMPHASIS_REACHED = 1 only when trasmitter programmed PRE-EMPHASIS_SET field (bits 4:3) to 11b (Level 3). Pre-emphasis level 3 is the maximum pre-emphasis level that the source supports.
Currently the MAX_PRE-EMPHASIS_REACHED bit is interpreted as the Max Pre-Emphasis level for certain Swing Level. This interpretation fails Link Layer compliance test 400.3.1.15 step 17 according to the following Fail condition: TRAINING_LANEx_SET.MAX_PRE-EMPHASIS_REACHED = 1 (check all active lanes) and the Source DUT supports pre-emphasis level 3 (9.5db).
Cc: Clint Taylor <Clinton.A.Taylor@xxxxxxxxx>
Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
Signed-off-by: Khaled Almahallawy <khaled.almahallawy@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_ddi.c | 20 --------------------
drivers/gpu/drm/i915/intel_dp.c | 2 +-
2 files changed, 1 insertion(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 0af47f343faa..6540c979c098 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -2239,26 +2239,6 @@ u8 intel_ddi_dp_voltage_max(struct intel_encoder *encoder)
DP_TRAIN_VOLTAGE_SWING_MASK;
}
-/*
- * We assume that the full set of pre-emphasis values can be
- * used on all DDI platforms. Should that change we need to
- * rethink this code.
- */
-u8 intel_ddi_dp_pre_emphasis_max(struct intel_encoder *encoder, u8 voltage_swing)
-{
- switch (voltage_swing & DP_TRAIN_VOLTAGE_SWING_MASK) {
- case DP_TRAIN_VOLTAGE_SWING_LEVEL_0:
- return DP_TRAIN_PRE_EMPH_LEVEL_3;
- case DP_TRAIN_VOLTAGE_SWING_LEVEL_1:
- return DP_TRAIN_PRE_EMPH_LEVEL_2;
- case DP_TRAIN_VOLTAGE_SWING_LEVEL_2:
- return DP_TRAIN_PRE_EMPH_LEVEL_1;
- case DP_TRAIN_VOLTAGE_SWING_LEVEL_3:
- default:
- return DP_TRAIN_PRE_EMPH_LEVEL_0;
- }
-}
-
static void cnl_ddi_vswing_program(struct intel_encoder *encoder,
int level, enum intel_output_type type)
{
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 77ba4da6b981..f94759e45862 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3541,7 +3541,7 @@ intel_dp_pre_emphasis_max(struct intel_dp *intel_dp, u8 voltage_swing)
enum port port = encoder->port;
if (HAS_DDI(dev_priv)) {
- return intel_ddi_dp_pre_emphasis_max(encoder, voltage_swing);
+ return DP_TRAIN_PRE_EMPH_LEVEL_3;
} else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
switch (voltage_swing & DP_TRAIN_VOLTAGE_SWING_MASK) {
case DP_TRAIN_VOLTAGE_SWING_LEVEL_0:
--
2.17.1
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