drm/i915/edp: Add a T12 panel delay quirk to fix DP AUX CH timeouts

This patch fixes the DP AUX CH timeouts observed during CI IGT
tests thus fixing the CI failures. This is done by adding a
quirk for a particular PCI device that requires the panel power
cycle delay (T12) to be set to 800ms which is 300msecs more than
the minimum value specified in the eDP spec. So a quirk is
implemented for that specific PCI device.

v4:
* Add Bugzilla links for FDO bugs in the commit message (Ville, Jani)
v3:
* Change some comments, specify the delay as 800 * 10 (Ville)
v2:
* Change the function and variable names to from PPS_T12_
to _T12 since it is a T12 delay (Clint)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101144
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101154
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101167
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101515
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Clinton Taylor <clinton.a.taylor@intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Clinton Taylor <clinton.a.taylor@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1498840428-23176-1-git-send-email-manasi.d.navare@intel.com
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

drivers/gpu/drm/i915/i915_drv.h

@@ -1166,6 +1166,7 @@ enum intel_sbi_destination {
 #define QUIRK_INVERT_BRIGHTNESS (1<<2)
 #define QUIRK_BACKLIGHT_PRESENT (1<<3)
 #define QUIRK_PIN_SWIZZLED_PAGES (1<<5)
+#define QUIRK_INCREASE_T12_DELAY (1<<6)
 
 struct intel_fbdev;
 struct intel_fbc_work;

drivers/gpu/drm/i915/intel_display.c

@@ -14771,6 +14771,17 @@ static void quirk_backlight_present(struct drm_device *dev)
 	DRM_INFO("applying backlight present quirk\n");
 }
 
+/* Toshiba Satellite P50-C-18C requires T12 delay to be min 800ms
+ * which is 300 ms greater than eDP spec T12 min.
+ */
+static void quirk_increase_t12_delay(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = to_i915(dev);
+
+	dev_priv->quirks |= QUIRK_INCREASE_T12_DELAY;
+	DRM_INFO("Applying T12 delay quirk\n");
+}
+
 struct intel_quirk {
 	int device;
 	int subsystem_vendor;
@@ -14854,6 +14865,9 @@ static struct intel_quirk intel_quirks[] = {
 
 	/* Dell Chromebook 11 (2015 version) */
 	{ 0x0a16, 0x1028, 0x0a35, quirk_backlight_present },
+
+	/* Toshiba Satellite P50-C-18C */
+	{ 0x191B, 0x1179, 0xF840, quirk_increase_t12_delay },
 };
 
 static void intel_init_quirks(struct drm_device *dev)

drivers/gpu/drm/i915/intel_dp.c

@@ -5255,6 +5255,16 @@ intel_dp_init_panel_power_sequencer(struct drm_device *dev,
 	intel_pps_dump_state("cur", &cur);
 
 	vbt = dev_priv->vbt.edp.pps;
+	/* On Toshiba Satellite P50-C-18C system the VBT T12 delay
+	 * of 500ms appears to be too short. Ocassionally the panel
+	 * just fails to power back on. Increasing the delay to 800ms
+	 * seems sufficient to avoid this problem.
+	 */
+	if (dev_priv->quirks & QUIRK_INCREASE_T12_DELAY) {
+		vbt.t11_t12 = max_t(u16, vbt.t11_t12, 800 * 10);
+		DRM_DEBUG_KMS("Increasing T12 panel delay as per the quirk to %d\n",
+			      vbt.t11_t12);
+	}
 	/* T11_T12 delay is special and actually in units of 100ms, but zero
 	 * based in the hw (so we need to add 100 ms). But the sw vbt
 	 * table multiplies it with 1000 to make it in units of 100usec,