[Intel-gfx] [PATCH] drm/i915/glk: Add Quirk for GLK NUC HDMI port issues.

[clinton.a.taylor at intel.com]

From: Clint Taylor <clinton.a.taylor at intel.com>

On GLK NUC platforms the HDMI retiming buffer needs additional disabled
time to correctly sync to a faster incoming signal.

When measured on a scope the highspeed lines of the HDMI clock turn off
 for ~400uS during a normal resolution change. The HDMI retimer on the
 GLK NUC appears to require at least a full frame of quiet time before a
new faster clock can be correctly sync'd. The worst case scenario appears
to be 23.98Hz modes which requires a wait of 41.25ms. Add a quirk to the
driver for GLK NUC that waits 42ms.

Cc: Imre Deak <imre.deak at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105887
Signed-off-by: Clint Taylor <clinton.a.taylor at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h      |  1 +
 drivers/gpu/drm/i915/intel_ddi.c     |  8 ++++++++
 drivers/gpu/drm/i915/intel_display.c | 14 ++++++++++++++
 3 files changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index c407366..628491d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -645,6 +645,7 @@ enum intel_sbi_destination {
 #define QUIRK_BACKLIGHT_PRESENT (1<<3)
 #define QUIRK_PIN_SWIZZLED_PAGES (1<<5)
 #define QUIRK_INCREASE_T12_DELAY (1<<6)
+#define QUIRK_INCREASE_DDI_DISABLED_TIME (1<<7)
 
 struct intel_fbdev;
 struct intel_fbc_work;
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index b344e0f..61b41c3 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1784,6 +1784,9 @@ void intel_ddi_enable_transcoder_func(const struct intel_crtc_state *crtc_state)
 	I915_WRITE(TRANS_DDI_FUNC_CTL(cpu_transcoder), temp);
 }
 
+/* Quirk time computed based on 24fps frame time of 41.25ms */
+#define DDI_DISABLED_QUIRK_TIME 42
+
 void intel_ddi_disable_transcoder_func(struct drm_i915_private *dev_priv,
 				       enum transcoder cpu_transcoder)
 {
@@ -1793,6 +1796,11 @@ void intel_ddi_disable_transcoder_func(struct drm_i915_private *dev_priv,
 	val &= ~(TRANS_DDI_FUNC_ENABLE | TRANS_DDI_PORT_MASK | TRANS_DDI_DP_VC_PAYLOAD_ALLOC);
 	val |= TRANS_DDI_PORT_NONE;
 	I915_WRITE(reg, val);
+
+	if (dev_priv->quirks & QUIRK_INCREASE_DDI_DISABLED_TIME) {
+		msleep(DDI_DISABLED_QUIRK_TIME);
+		DRM_DEBUG_KMS("Quirk Increase DDI disabled time\n");
+	}
 }
 
 int intel_ddi_toggle_hdcp_signalling(struct intel_encoder *intel_encoder,
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index ed29219..0d07c37 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14740,6 +14740,17 @@ static void quirk_increase_t12_delay(struct drm_device *dev)
 	DRM_INFO("Applying T12 delay quirk\n");
 }
 
+/* GeminiLake NUC HDMI outputs require additional off time
+ * this allows the onboard retimer to correctly sync to signal
+ */
+static void quirk_increase_ddi_disabled_time(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = to_i915(dev);
+
+	dev_priv->quirks |= QUIRK_INCREASE_DDI_DISABLED_TIME;
+	DRM_INFO("Applying Increase DDI Disabled quirk\n");
+}
+
 struct intel_quirk {
 	int device;
 	int subsystem_vendor;
@@ -14826,6 +14837,9 @@ static int intel_dmi_reverse_brightness(const struct dmi_system_id *id)
 
 	/* Toshiba Satellite P50-C-18C */
 	{ 0x191B, 0x1179, 0xF840, quirk_increase_t12_delay },
+
+	/* GeminiLake NUC */
+	{ 0x3185, 0x8086, 0x2072, quirk_increase_ddi_disabled_time },
 };
 
 static void intel_init_quirks(struct drm_device *dev)
-- 
1.9.1