drm/i915/vlv: reset DPIO on load and resume v2

DPIO needs to have common reset de-asserted on soft resets like boot and
S3.  In some cases, the BIOS will have done this for us, but it should
be safe to do at runtime as well, as long as we do it when the pipes are
otherwise off.

v2: update bit name to match docs better (Ville)
    reset after CRI clock select (Ville)

References: https://bugs.freedesktop.org/show_bug.cgi?id=69166
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 169d6825f9e..214984c814e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1360,6 +1360,26 @@ static void assert_pch_ports_disabled(struct drm_i915_private *dev_priv,
 	assert_pch_hdmi_disabled(dev_priv, pipe, PCH_HDMID);
 }
 
+static void intel_init_dpio(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (!IS_VALLEYVIEW(dev))
+		return;
+
+	/*
+	 * From VLV2A0_DP_eDP_DPIO_driver_vbios_notes_10.docx -
+	 *  6.	De-assert cmn_reset/side_reset. Same as VLV X0.
+	 *   a.	GUnit 0x2110 bit[0] set to 1 (def 0)
+	 *   b.	The other bits such as sfr settings / modesel may all be set
+	 *      to 0.
+	 *
+	 * This should only be done on init and resume from S3 with both
+	 * PLLs disabled, or we risk losing DPIO and PLL synchronization.
+	 */
+	I915_WRITE(DPIO_CTL, I915_READ(DPIO_CTL) | DPIO_CMNRST);
+}
+
 static void vlv_enable_pll(struct intel_crtc *crtc)
 {
 	struct drm_device *dev = crtc->base.dev;
@@ -10370,6 +10390,8 @@ void intel_modeset_init_hw(struct drm_device *dev)
 		I915_WRITE(DPLL(PIPE_B), I915_READ(DPLL(PIPE_B)) |
 			   DPLL_INTEGRATED_CRI_CLK_VLV);
 
+	intel_init_dpio(dev);
+
 	mutex_lock(&dev->struct_mutex);
 	intel_enable_gt_powersave(dev);
 	mutex_unlock(&dev->struct_mutex);