drm/i915: HDMI hardware workaround for Ironlake
This brings some hardware workaround for HDMI port on PCH (Ibex Peak),
which fixes unstable issues like during rotation.
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 663ab6d..c33451a 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -77,14 +77,32 @@
struct intel_hdmi_priv *hdmi_priv = intel_output->dev_priv;
u32 temp;
- if (mode != DRM_MODE_DPMS_ON) {
- temp = I915_READ(hdmi_priv->sdvox_reg);
+ temp = I915_READ(hdmi_priv->sdvox_reg);
+
+ /* HW workaround, need to toggle enable bit off and on for 12bpc, but
+ * we do this anyway which shows more stable in testing.
+ */
+ if (IS_IGDNG(dev)) {
I915_WRITE(hdmi_priv->sdvox_reg, temp & ~SDVO_ENABLE);
- } else {
- temp = I915_READ(hdmi_priv->sdvox_reg);
- I915_WRITE(hdmi_priv->sdvox_reg, temp | SDVO_ENABLE);
+ POSTING_READ(hdmi_priv->sdvox_reg);
}
+
+ if (mode != DRM_MODE_DPMS_ON) {
+ temp &= ~SDVO_ENABLE;
+ } else {
+ temp |= SDVO_ENABLE;
+ }
+
+ I915_WRITE(hdmi_priv->sdvox_reg, temp);
POSTING_READ(hdmi_priv->sdvox_reg);
+
+ /* HW workaround, need to write this twice for issue that may result
+ * in first write getting masked.
+ */
+ if (IS_IGDNG(dev)) {
+ I915_WRITE(hdmi_priv->sdvox_reg, temp);
+ POSTING_READ(hdmi_priv->sdvox_reg);
+ }
}
static void intel_hdmi_save(struct drm_connector *connector)