drm/i915: Don't try to use the hardware frame counter with i965gm TV output

From Ville Syrjala
32db0b6501d97b09e92e70caefc74fa35aa9a8d6 in mainline linux

Jon Whalen reported on misc@ that a 965gm with svideo on a
Dell Inspiron 1525 had excesively long timeouts.  On the order of 30
seconds when booting and 60 seconds when starting xenocara with errors
showing up in dmesg.

While the other commit referenced in
https://bugs.freedesktop.org/show_bug.cgi?id=93782 appeared in the
4.19 lts branch this one while being marked for stable in the linux
commit never did.

2 files changed, 59 insertions, 17 deletions

diff --git a/sys/dev/pci/drm/i915/i915_irq.c b/sys/dev/pci/drm/i915/i915_irq.c
index bbff451d8ff..aca808d5d5c 100644
--- a/sys/dev/pci/drm/i915/i915_irq.c
+++ b/sys/dev/pci/drm/i915/i915_irq.c
@@ -822,11 +822,26 @@ static void i915_enable_asle_pipestat(struct drm_i915_private *dev_priv)
 static u32 i915_get_vblank_counter(struct drm_device *dev, unsigned int pipe)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
+	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
+	const struct drm_display_mode *mode = &vblank->hwmode;
 	i915_reg_t high_frame, low_frame;
 	u32 high1, high2, low, pixel, vbl_start, hsync_start, htotal;
-	const struct drm_display_mode *mode = &dev->vblank[pipe].hwmode;
 	unsigned long irqflags;
 
+	/*
+	 * On i965gm TV output the frame counter only works up to
+	 * the point when we enable the TV encoder. After that the
+	 * frame counter ceases to work and reads zero. We need a
+	 * vblank wait before enabling the TV encoder and so we
+	 * have to enable vblank interrupts while the frame counter
+	 * is still in a working state. However the core vblank code
+	 * does not like us returning non-zero frame counter values
+	 * when we've told it that we don't have a working frame
+	 * counter. Thus we must stop non-zero values leaking out.
+	 */
+	if (!vblank->max_vblank_count)
+		return 0;
+
 	htotal = mode->crtc_htotal;
 	hsync_start = mode->crtc_hsync_start;
 	vbl_start = mode->crtc_vblank_start;
@@ -4803,16 +4818,10 @@ void intel_irq_init(struct drm_i915_private *dev_priv)
 	if (INTEL_GEN(dev_priv) >= 8)
 		rps->pm_intrmsk_mbz |= GEN8_PMINTR_DISABLE_REDIRECT_TO_GUC;
 
-	if (IS_GEN2(dev_priv)) {
-		/* Gen2 doesn't have a hardware frame counter */
-		dev->max_vblank_count = 0;
-	} else if (IS_G4X(dev_priv) || INTEL_GEN(dev_priv) >= 5) {
-		dev->max_vblank_count = 0xffffffff; /* full 32 bit counter */
+	if (INTEL_GEN(dev_priv) >= 5 || IS_G4X(dev_priv))
 		dev->driver->get_vblank_counter = g4x_get_vblank_counter;
-	} else {
+	else if (INTEL_GEN(dev_priv) >= 3)
 		dev->driver->get_vblank_counter = i915_get_vblank_counter;
-		dev->max_vblank_count = 0xffffff; /* only 24 bits of frame count */
-	}
 
 	/*
 	 * Opt out of the vblank disable timer on everything except gen2.
diff --git a/sys/dev/pci/drm/i915/intel_display.c b/sys/dev/pci/drm/i915/intel_display.c
index 63a460c9b20..79580e8a758 100644
--- a/sys/dev/pci/drm/i915/intel_display.c
+++ b/sys/dev/pci/drm/i915/intel_display.c
@@ -1816,6 +1816,35 @@ enum pipe intel_crtc_pch_transcoder(struct intel_crtc *crtc)
 		return crtc->pipe;
 }
 
+static u32 intel_crtc_max_vblank_count(const struct intel_crtc_state *crtc_state)
+{
+	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
+
+	/*
+	 * On i965gm the hardware frame counter reads
+	 * zero when the TV encoder is enabled :(
+	 */
+	if (IS_I965GM(dev_priv) &&
+	    (crtc_state->output_types & BIT(INTEL_OUTPUT_TVOUT)))
+		return 0;
+
+	if (INTEL_GEN(dev_priv) >= 5 || IS_G4X(dev_priv))
+		return 0xffffffff; /* full 32 bit counter */
+	else if (INTEL_GEN(dev_priv) >= 3)
+		return 0xffffff; /* only 24 bits of frame count */
+	else
+		return 0; /* Gen2 doesn't have a hardware frame counter */
+}
+
+static void intel_crtc_vblank_on(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
+
+	drm_crtc_set_max_vblank_count(&crtc->base,
+				      intel_crtc_max_vblank_count(crtc_state));
+	drm_crtc_vblank_on(&crtc->base);
+}
+
 static void intel_enable_pipe(const struct intel_crtc_state *new_crtc_state)
 {
 	struct intel_crtc *crtc = to_intel_crtc(new_crtc_state->base.crtc);
@@ -1868,7 +1897,7 @@ static void intel_enable_pipe(const struct intel_crtc_state *new_crtc_state)
 	 * when it's derived from the timestamps. So let's wait for the
 	 * pipe to start properly before we call drm_crtc_vblank_on()
 	 */
-	if (dev_priv->drm.max_vblank_count == 0)
+	if (intel_crtc_max_vblank_count(new_crtc_state) == 0)
 		intel_wait_for_pipe_scanline_moving(crtc);
 }
 
@@ -5600,7 +5629,7 @@ static void ironlake_crtc_enable(struct intel_crtc_state *pipe_config,
 		ironlake_pch_enable(old_intel_state, pipe_config);
 
 	assert_vblank_disabled(crtc);
-	drm_crtc_vblank_on(crtc);
+	intel_crtc_vblank_on(pipe_config);
 
 	intel_encoders_enable(crtc, pipe_config, old_state);
 
@@ -5758,7 +5787,7 @@ static void haswell_crtc_enable(struct intel_crtc_state *pipe_config,
 		intel_ddi_set_vc_payload_alloc(pipe_config, true);
 
 	assert_vblank_disabled(crtc);
-	drm_crtc_vblank_on(crtc);
+	intel_crtc_vblank_on(pipe_config);
 
 	intel_encoders_enable(crtc, pipe_config, old_state);
 
@@ -6064,7 +6093,7 @@ static void valleyview_crtc_enable(struct intel_crtc_state *pipe_config,
 	intel_enable_pipe(pipe_config);
 
 	assert_vblank_disabled(crtc);
-	drm_crtc_vblank_on(crtc);
+	intel_crtc_vblank_on(pipe_config);
 
 	intel_encoders_enable(crtc, pipe_config, old_state);
 }
@@ -6123,7 +6152,7 @@ static void i9xx_crtc_enable(struct intel_crtc_state *pipe_config,
 	intel_enable_pipe(pipe_config);
 
 	assert_vblank_disabled(crtc);
-	drm_crtc_vblank_on(crtc);
+	intel_crtc_vblank_on(pipe_config);
 
 	intel_encoders_enable(crtc, pipe_config, old_state);
 }
@@ -12414,8 +12443,9 @@ static int intel_atomic_prepare_commit(struct drm_device *dev,
 u32 intel_crtc_get_vblank_counter(struct intel_crtc *crtc)
 {
 	struct drm_device *dev = crtc->base.dev;
+	struct drm_vblank_crtc *vblank = &dev->vblank[drm_crtc_index(&crtc->base)];
 
-	if (!dev->max_vblank_count)
+	if (!vblank->max_vblank_count)
 		return (u32)drm_crtc_accurate_vblank_count(&crtc->base);
 
 	return dev->driver->get_vblank_counter(dev, crtc->pipe);
@@ -15846,10 +15876,13 @@ intel_modeset_setup_hw_state(struct drm_device *dev,
 	 * waits, so we need vblank interrupts restored beforehand.
 	 */
 	for_each_intel_crtc(&dev_priv->drm, crtc) {
+		struct intel_crtc_state * crtc_state =
+			to_intel_crtc_state(crtc->base.state);
+
 		drm_crtc_vblank_reset(&crtc->base);
 
-		if (crtc->active)
-			drm_crtc_vblank_on(&crtc->base);
+		if (crtc_state->base.active)
+			intel_crtc_vblank_on(crtc_state);
 	}
 
 	intel_sanitize_plane_mapping(dev_priv);