drm/i915: Set correct TV detection voltage level override values

We detect TV connect status by setting DAC voltage level override
values as 0.7 voltage for DAC_A/B/C. The corresponding 2-bits shold be 0x2,
In order correctly to set last bit as 0, at first we must clean it.

It fixed freedesktop.org bug #21204

Signed-off-by: Ma Ling <ling.ma@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

2 files changed, 6 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 99681cfb7ab9..79df9e9c38e4 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -958,15 +958,15 @@
 # define DAC_A_1_3_V                    (0 << 4)
 # define DAC_A_1_1_V                    (1 << 4)
 # define DAC_A_0_7_V                    (2 << 4)
-# define DAC_A_OFF                      (3 << 4)
+# define DAC_A_MASK                     (3 << 4)
 # define DAC_B_1_3_V                    (0 << 2)
 # define DAC_B_1_1_V                    (1 << 2)
 # define DAC_B_0_7_V                    (2 << 2)
-# define DAC_B_OFF                      (3 << 2)
+# define DAC_B_MASK                     (3 << 2)
 # define DAC_C_1_3_V                    (0 << 0)
 # define DAC_C_1_1_V                    (1 << 0)
 # define DAC_C_0_7_V                    (2 << 0)
-# define DAC_C_OFF                      (3 << 0)
+# define DAC_C_MASK                     (3 << 0)
 
 /**
  * CSC coefficients are stored in a floating point format with 9 bits of
diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
index d2c32983242d..c7d9ef01dbf6 100644
--- a/drivers/gpu/drm/i915/intel_tv.c
+++ b/drivers/gpu/drm/i915/intel_tv.c
@@ -1392,6 +1392,9 @@ intel_tv_detect_type (struct drm_crtc *crtc, struct intel_output *intel_output)
                 tv_ctl &= ~TV_TEST_MODE_MASK;
                 tv_ctl |= TV_TEST_MODE_MONITOR_DETECT;
                 tv_dac &= ~TVDAC_SENSE_MASK;
+                tv_dac &= ~DAC_A_MASK;
+                tv_dac &= ~DAC_B_MASK;
+                tv_dac &= ~DAC_C_MASK;
                 tv_dac |= (TVDAC_STATE_CHG_EN |
                            TVDAC_A_SENSE_CTL |
                            TVDAC_B_SENSE_CTL |