From: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
Even if the panel claims it can support 4 lanes, there's the
possibility that the HW can't, so consider this while selecting the
max lane count.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 87b0a515d7a5..3dde9076d9d7 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -121,6 +121,22 @@ intel_dp_max_link_bw(struct intel_dp *intel_dp)
return max_link_bw;
}
+static u8 intel_dp_max_lane_count(struct intel_dp *intel_dp)
+{
+ struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+ struct drm_device *dev = intel_dig_port->base.base.dev;
+ u8 source_max, sink_max;
+
+ source_max = 4;
+ if (HAS_DDI(dev) && intel_dig_port->port == PORT_A &&
+ (intel_dig_port->saved_port_bits & DDI_A_4_LANES) == 0)
+ source_max = 2;
+
+ sink_max = drm_dp_max_lane_count(intel_dp->dpcd);
+
+ return min(source_max, sink_max);
+}
+
/*
* The units on the numbers in the next two are... bizarre. Examples will
* make it clearer; this one parallels an example in the eDP spec.
@@ -171,7 +187,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
}
max_link_clock = drm_dp_bw_code_to_link_rate(intel_dp_max_link_bw(intel_dp));
- max_lanes = drm_dp_max_lane_count(intel_dp->dpcd);
+ max_lanes = intel_dp_max_lane_count(intel_dp);
max_rate = intel_dp_max_data_rate(max_link_clock, max_lanes);
mode_rate = intel_dp_link_required(target_clock, 18);
@@ -769,7 +785,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
struct intel_crtc *intel_crtc = encoder->new_crtc;
struct intel_connector *intel_connector = intel_dp->attached_connector;
int lane_count, clock;
- int max_lane_count = drm_dp_max_lane_count(intel_dp->dpcd);
+ int max_lane_count = intel_dp_max_lane_count(intel_dp);
/* Conveniently, the link BW constants become indices with a shift...*/
int max_clock = intel_dp_max_link_bw(intel_dp) >> 3;
int bpp, mode_rate;
--
1.9.1
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