In commit bfb9faab8 we added a workaround for some BXT BIOS that fail to
properly initialize the DDI_A_4_LANES bit of the control register (4
lanes is the only valid configuration on BXT since there is no DDI E to
share with). A recent patch added some additional checks on this
register bit before the workaround gets applied; this breaks eDP on BXT
in some settings. Some minor code shuffling is all we need to restore
the workaround.
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Fixes: 7cd87cb80 ("drm/i915: Check max number of lanes when registering DDI ports")
Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_ddi.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 75b57a8..6ac80cd 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -3288,7 +3288,6 @@ void intel_ddi_init(struct drm_device *dev, enum port port)
intel_dig_port->saved_port_bits = I915_READ(DDI_BUF_CTL(port)) &
(DDI_BUF_PORT_REVERSAL |
DDI_A_4_LANES);
- intel_dig_port->max_lanes = max_lanes;
/*
* Bspec says that DDI_A_4_LANES is the only supported configuration
@@ -3301,9 +3300,12 @@ void intel_ddi_init(struct drm_device *dev, enum port port)
if (!(intel_dig_port->saved_port_bits & DDI_A_4_LANES)) {
DRM_DEBUG_KMS("BXT BIOS forgot to set DDI_A_4_LANES for port A; fixing\n");
intel_dig_port->saved_port_bits |= DDI_A_4_LANES;
+ max_lanes = 4;
}
}
+ intel_dig_port->max_lanes = max_lanes;
+
intel_encoder->type = INTEL_OUTPUT_UNKNOWN;
intel_encoder->crtc_mask = (1 << 0) | (1 << 1) | (1 << 2);
intel_encoder->cloneable = 0;
--
2.1.4
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