drm/i915: Preserve the DDI_A_4_LANES bit from the bios

Otherwise the DDI_A_4_LANES bit gets lost and we can't use > 2 lanes
on eDP. This fixes eDP on hsw with > 2 lanes.

Also s/port_reversal/saved_port_bits/ since the current name is
confusing.

Signed-off-by: Stéphane Marchesin <marcheu@chromium.org>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

2 files changed, 7 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 324211ac9c55..b042ee5c4070 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -301,7 +301,7 @@ static void intel_ddi_mode_set(struct drm_encoder *encoder,
                 struct intel_digital_port *intel_dig_port =
                         enc_to_dig_port(encoder);
 
-                intel_dp->DP = intel_dig_port->port_reversal |
+                intel_dp->DP = intel_dig_port->saved_port_bits |
                                DDI_BUF_CTL_ENABLE | DDI_BUF_EMP_400MV_0DB_HSW;
                 intel_dp->DP |= DDI_PORT_WIDTH(intel_dp->lane_count);
 
@@ -1109,7 +1109,8 @@ static void intel_enable_ddi(struct intel_encoder *intel_encoder)
                  * enabling the port.
                  */
                 I915_WRITE(DDI_BUF_CTL(port),
-                           intel_dig_port->port_reversal | DDI_BUF_CTL_ENABLE);
+                           intel_dig_port->saved_port_bits |
+                           DDI_BUF_CTL_ENABLE);
         } else if (type == INTEL_OUTPUT_EDP) {
                 struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 
@@ -1347,8 +1348,9 @@ void intel_ddi_init(struct drm_device *dev, enum port port)
         intel_encoder->get_config = intel_ddi_get_config;
 
         intel_dig_port->port = port;
-        intel_dig_port->port_reversal = I915_READ(DDI_BUF_CTL(port)) &
-                                        DDI_BUF_PORT_REVERSAL;
+        intel_dig_port->saved_port_bits = I915_READ(DDI_BUF_CTL(port)) &
+                                          (DDI_BUF_PORT_REVERSAL |
+                                           DDI_A_4_LANES);
         intel_dig_port->dp.output_reg = DDI_BUF_CTL(port);
 
         intel_encoder->type = INTEL_OUTPUT_UNKNOWN;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index c8c9b6f48230..b7d6e09456ce 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -504,7 +504,7 @@ struct intel_dp {
 struct intel_digital_port {
         struct intel_encoder base;
         enum port port;
-        u32 port_reversal;
+        u32 saved_port_bits;
         struct intel_dp dp;
         struct intel_hdmi hdmi;
 };