drm/i915/dp: make eDP PLL functions work as advertised

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index ada7319f0eaf..128c2fefd541 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -891,8 +891,10 @@ static void ironlake_edp_pll_on(struct drm_encoder *encoder)
 
         DRM_DEBUG_KMS("\n");
         dpa_ctl = I915_READ(DP_A);
-        dpa_ctl &= ~DP_PLL_ENABLE;
+        dpa_ctl |= DP_PLL_ENABLE;
         I915_WRITE(DP_A, dpa_ctl);
+        POSTING_READ(DP_A);
+        udelay(200);
 }
 
 static void ironlake_edp_pll_off(struct drm_encoder *encoder)
@@ -902,7 +904,7 @@ static void ironlake_edp_pll_off(struct drm_encoder *encoder)
         u32 dpa_ctl;
 
         dpa_ctl = I915_READ(DP_A);
-        dpa_ctl |= DP_PLL_ENABLE;
+        dpa_ctl &= ~DP_PLL_ENABLE;
         I915_WRITE(DP_A, dpa_ctl);
         POSTING_READ(DP_A);
         udelay(200);