drm/i915: Sanitize BIOS debugging bits from PIPECONF

[firefly-linux-kernel-4.4.55.git] / drivers / gpu / drm / i915 / intel_display.c

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index d514719f65e26516a823577a8ef3e5c161ffb5a8..078477306975351e52565027b8f8a370b5a0f256 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7580,6 +7580,12 @@ static void intel_sanitize_modesetting(struct drm_device *dev,
        struct drm_i915_private *dev_priv = dev->dev_private;
        u32 reg, val;
 
+       /* Clear any frame start delays used for debugging left by the BIOS */
+       for_each_pipe(pipe) {
+               reg = PIPECONF(pipe);
+               I915_WRITE(reg, I915_READ(reg) & ~PIPECONF_FRAME_START_DELAY_MASK);
+       }
+
        if (HAS_PCH_SPLIT(dev))
                return;