[PATCH] drm/i915/display: Prevent DC6 while vblank is enabled for Panel Replay

["Jouni Högander" <jouni.hogander@intel.com>]

We need to block DC6 entry in case of Panel Replay as enabling VBI doesn't
prevent DC6 in case of Panel Replay. This causes problems if user-space is
polling for vblank events.

Fix this by setting target DC state as DC_STATE_EN_UPTO_DC5 when both
source and sink are supporting eDP Panel Replay and VBI is enabled.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2296
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
---
 .../gpu/drm/i915/display/intel_display_core.h |  2 +
 .../gpu/drm/i915/display/intel_display_irq.c  | 48 +++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h b/drivers/gpu/drm/i915/display/intel_display_core.h
index 0a711114ff2b4..0707bc2047931 100644
--- a/drivers/gpu/drm/i915/display/intel_display_core.h
+++ b/drivers/gpu/drm/i915/display/intel_display_core.h
@@ -457,6 +457,8 @@ struct intel_display {
 		/* For i915gm/i945gm vblank irq workaround */
 		u8 vblank_enabled;
 
+		struct work_struct vblank_work;
+
 		u32 de_irq_mask[I915_MAX_PIPES];
 		u32 pipestat_irq_mask[I915_MAX_PIPES];
 	} irq;
diff --git a/drivers/gpu/drm/i915/display/intel_display_irq.c b/drivers/gpu/drm/i915/display/intel_display_irq.c
index 8f13f148c73e3..96abfb356349e 100644
--- a/drivers/gpu/drm/i915/display/intel_display_irq.c
+++ b/drivers/gpu/drm/i915/display/intel_display_irq.c
@@ -15,6 +15,7 @@
 #include "intel_display_irq.h"
 #include "intel_display_trace.h"
 #include "intel_display_types.h"
+#include "intel_dp.h"
 #include "intel_dp_aux.h"
 #include "intel_dsb.h"
 #include "intel_fdi_regs.h"
@@ -1361,9 +1362,47 @@ static bool gen11_dsi_configure_te(struct intel_crtc *intel_crtc,
 	return true;
 }
 
+static void intel_display_vblank_work(struct work_struct *work)
+{
+	struct intel_display *display =
+		container_of(work, typeof(*display), irq.vblank_work);
+	struct drm_i915_private *i915 = to_i915(display->drm);
+
+	/*
+	 * NOTE: intel_display_power_set_target_dc_state is used only by PSR
+	 * code for DC3CO handling. DC3CO target states is currently disabled in
+	 * PSR code. If DC3CO is taken into use we need take that into account
+	 * here as well.
+	 */
+	intel_display_power_set_target_dc_state(i915, display->irq.vblank_enabled ?
+						DC_STATE_EN_UPTO_DC5 : DC_STATE_EN_UPTO_DC6);
+}
+
+/*
+ * We need to block DC6 entry in case of Panel Replay as enabling VBI doesn't
+ * prevent DC6 in case of Panel Replay. This causes problems if user-space is
+ * polling for vblank events.
+ */
+static bool block_dc6_needed(struct intel_display *display)
+{
+	struct intel_encoder *encoder;
+
+	for_each_intel_encoder_with_psr(display->drm, encoder) {
+		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
+
+		if (!intel_dp_is_edp(intel_dp))
+			continue;
+
+		if (CAN_PANEL_REPLAY(intel_dp))
+			return true;
+	}
+	return false;
+}
+
 int bdw_enable_vblank(struct drm_crtc *_crtc)
 {
 	struct intel_crtc *crtc = to_intel_crtc(_crtc);
+	struct intel_display *display = to_intel_display(crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	enum pipe pipe = crtc->pipe;
 	unsigned long irqflags;
@@ -1371,6 +1410,9 @@ int bdw_enable_vblank(struct drm_crtc *_crtc)
 	if (gen11_dsi_configure_te(crtc, true))
 		return 0;
 
+	if (block_dc6_needed(display) && display->irq.vblank_enabled++ == 0)
+		schedule_work(&display->irq.vblank_work);
+
 	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
 	bdw_enable_pipe_irq(dev_priv, pipe, GEN8_PIPE_VBLANK);
 	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
@@ -1436,6 +1478,7 @@ void ilk_disable_vblank(struct drm_crtc *crtc)
 void bdw_disable_vblank(struct drm_crtc *_crtc)
 {
 	struct intel_crtc *crtc = to_intel_crtc(_crtc);
+	struct intel_display *display = to_intel_display(crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	enum pipe pipe = crtc->pipe;
 	unsigned long irqflags;
@@ -1446,6 +1489,9 @@ void bdw_disable_vblank(struct drm_crtc *_crtc)
 	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
 	bdw_disable_pipe_irq(dev_priv, pipe, GEN8_PIPE_VBLANK);
 	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
+
+	if (block_dc6_needed(display) && --display->irq.vblank_enabled == 0)
+		schedule_work(&display->irq.vblank_work);
 }
 
 void vlv_display_irq_reset(struct drm_i915_private *dev_priv)
@@ -1871,4 +1917,6 @@ void intel_display_irq_init(struct drm_i915_private *i915)
 		i915->display.irq.display_irqs_enabled = false;
 
 	intel_hotplug_irq_init(i915);
+
+	INIT_WORK(&i915->display.irq.vblank_work, intel_display_vblank_work);
 }
-- 
2.34.1