drm/i915/bxt: VSwing programming sequence

VSwing programming sequence as specified in the updated BXT BSpec

v2: Satheesh's review comments addressed.
- clear value before setting into registers
- move print statement to bxt function
Other changes
- since signal level will not be set into DDI_BUF_CTL, the value need
  not be returned to intel_dp_set_signal_levels(). Making the bxt
  specific function to return void and setting signal_levels = 0 for
  bxt inside intel_dp_set_signal_levels()
- instead of signal levels, printing vswing level and pre-emphasis
  level
- in case none of the pre-emphasis levels or vswing levels are set,
  setting default of 400mV + 0dB

v3: Satheesh's review comments
- Check for mask before printing signal_levels.
- Removing redundant register writes
- Call intel_prepare_ddi_buffers only for HAS_PCH_SPLIT
- Making register write part generic as it will be required for HDMI as
  well.

Re-structure the code to include an array for vswing related values, set
signal levels

v4: Satheesh's review comments
- Rebase over latest renaming patches
- use hsw_signal_levels for HAS_DDI
Other changes
- Modified vswing_sequence() func definition
- Rebased on top of register macro definitions

v5: Satheesh's review comments
- Check ddi translation table size

v6: Imre's review comments
- removed comments in vswing sequence
- added vswing, pre-emphasis prints in intel_dp_set_signal_levels
- added comment explaining use of DP vswing values for eDP
- initialize n_entries and ddi_transaltion table based on encoder type
- create bxt_ddi_buf_trans structure and use decimal values
- adding a flag in bxt buffer translation table to indicate def entry

v7: (imre)
- squash in Vandana's "VSwing register definition",
  "HDMI VSwing programming", "Re-enable vswing programming",
  "Fix vswing sequence" patches
- use BXT_PORT_* regs directly instead of via a temp var
- simplify BXT_PORT_* macro definitions
- add code comment why we read lane while write group registers
- fix readout of DP_TRAIN_PRE_EMPHASIS in debug message

Signed-off-by: Vandana Kannan <vandana.kannan@intel.com> (v6)
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 62 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 550ac9be1f58..2e27b5215a36 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3409,6 +3409,55 @@ intel_hsw_signal_levels(uint8_t train_set)
 	}
 }
 
+static void intel_bxt_signal_levels(struct intel_dp *intel_dp)
+{
+	struct intel_digital_port *dport = dp_to_dig_port(intel_dp);
+	enum port port = dport->port;
+	struct drm_device *dev = dport->base.base.dev;
+	struct intel_encoder *encoder = &dport->base;
+	uint8_t train_set = intel_dp->train_set[0];
+	uint32_t level = 0;
+
+	int signal_levels = train_set & (DP_TRAIN_VOLTAGE_SWING_MASK |
+					 DP_TRAIN_PRE_EMPHASIS_MASK);
+	switch (signal_levels) {
+	default:
+		DRM_DEBUG_KMS("Unsupported voltage swing/pre-emph level\n");
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_0:
+		level = 0;
+		break;
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_1:
+		level = 1;
+		break;
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_2:
+		level = 2;
+		break;
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_3:
+		level = 3;
+		break;
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_1 | DP_TRAIN_PRE_EMPH_LEVEL_0:
+		level = 4;
+		break;
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_1 | DP_TRAIN_PRE_EMPH_LEVEL_1:
+		level = 5;
+		break;
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_1 | DP_TRAIN_PRE_EMPH_LEVEL_2:
+		level = 6;
+		break;
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_2 | DP_TRAIN_PRE_EMPH_LEVEL_0:
+		level = 7;
+		break;
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_2 | DP_TRAIN_PRE_EMPH_LEVEL_1:
+		level = 8;
+		break;
+	case DP_TRAIN_VOLTAGE_SWING_LEVEL_3 | DP_TRAIN_PRE_EMPH_LEVEL_0:
+		level = 9;
+		break;
+	}
+
+	bxt_ddi_vswing_sequence(dev, level, port, encoder->type);
+}
+
 /* Properly updates "DP" with the correct signal levels. */
 static void
 intel_dp_set_signal_levels(struct intel_dp *intel_dp, uint32_t *DP)
@@ -3419,7 +3468,11 @@ intel_dp_set_signal_levels(struct intel_dp *intel_dp, uint32_t *DP)
 	uint32_t signal_levels, mask;
 	uint8_t train_set = intel_dp->train_set[0];
 
-	if (IS_HASWELL(dev) || IS_BROADWELL(dev) || INTEL_INFO(dev)->gen >= 9) {
+	if (IS_BROXTON(dev)) {
+		signal_levels = 0;
+		intel_bxt_signal_levels(intel_dp);
+		mask = 0;
+	} else if (HAS_DDI(dev)) {
 		signal_levels = intel_hsw_signal_levels(train_set);
 		mask = DDI_BUF_EMP_MASK;
 	} else if (IS_CHERRYVIEW(dev)) {
@@ -3439,7 +3492,14 @@ intel_dp_set_signal_levels(struct intel_dp *intel_dp, uint32_t *DP)
 		mask = DP_VOLTAGE_MASK | DP_PRE_EMPHASIS_MASK;
 	}
 
-	DRM_DEBUG_KMS("Using signal levels %08x\n", signal_levels);
+	if (mask)
+		DRM_DEBUG_KMS("Using signal levels %08x\n", signal_levels);
+
+	DRM_DEBUG_KMS("Using vswing level %d\n",
+		train_set & DP_TRAIN_VOLTAGE_SWING_MASK);
+	DRM_DEBUG_KMS("Using pre-emphasis level %d\n",
+		(train_set & DP_TRAIN_PRE_EMPHASIS_MASK) >>
+			DP_TRAIN_PRE_EMPHASIS_SHIFT);
 
 	*DP = (*DP & ~mask) | signal_levels;
 }