drm/i915/sdvo: always set positive sync polarity

This is a revert of 81a14b46.

We already set the mode polarity using the SDVO commands with struct
intel_sdvo_dtd. We have at least 3 bugs that get fixed with this patch.
The documentation, despite not clear, can also be interpreted in a way
that suggests this patch is needed.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=15766
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=42174
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=43333
Cc: stable@kernel.org
Reviewed-by: NEric Anholt <eric@anholt.net>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NKeith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_sdvo.c

@@ -1066,15 +1066,13 @@ static void intel_sdvo_mode_set(struct drm_encoder *encoder,
 
 	/* Set the SDVO control regs. */
 	if (INTEL_INFO(dev)->gen >= 4) {
-		sdvox = 0;
+		/* The real mode polarity is set by the SDVO commands, using
+		 * struct intel_sdvo_dtd. */
+		sdvox = SDVO_VSYNC_ACTIVE_HIGH | SDVO_HSYNC_ACTIVE_HIGH;
 		if (intel_sdvo->is_hdmi)
 			sdvox |= intel_sdvo->color_range;
 		if (INTEL_INFO(dev)->gen < 5)
 			sdvox |= SDVO_BORDER_ENABLE;
-		if (adjusted_mode->flags & DRM_MODE_FLAG_PVSYNC)
-			sdvox |= SDVO_VSYNC_ACTIVE_HIGH;
-		if (adjusted_mode->flags & DRM_MODE_FLAG_PHSYNC)
-			sdvox |= SDVO_HSYNC_ACTIVE_HIGH;
 	} else {
 		sdvox = I915_READ(intel_sdvo->sdvo_reg);
 		switch (intel_sdvo->sdvo_reg) {