drm/i915: Handle pipe CRC around enabling/disabling pipe.

This will get rid of the following error:
[   74.730271] WARNING: CPU: 4 PID: 0 at drivers/gpu/drm/drm_vblank.c:614 drm_calc_vbltimestamp_from_scanoutpos+0x13e/0x2f0
[   74.730311] Modules linked in: vgem snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic i915 x86_pkg_temp_thermal intel_powerclamp coretemp snd_hda_intel crct10dif_pclmul snd_hda_codec crc32_pclmul snd_hwdep broadcom ghash_clmulni_intel snd_hda_core bcm_phy_lib snd_pcm tg3 lpc_ich mei_me mei prime_numbers
[   74.730353] CPU: 4 PID: 0 Comm: swapper/4 Tainted: G     U           4.16.0-rc2-CI-CI_DRM_3822+ #1
[   74.730355] Hardware name: Dell Inc. XPS 8300  /0Y2MRG, BIOS A06 10/17/2011
[   74.730359] RIP: 0010:drm_calc_vbltimestamp_from_scanoutpos+0x13e/0x2f0
[   74.730361] RSP: 0018:ffff88022fb03d10 EFLAGS: 00010086
[   74.730365] RAX: ffffffffa0291d20 RBX: ffff88021a180000 RCX: 0000000000000001
[   74.730367] RDX: ffffffff820e7db8 RSI: 0000000000000001 RDI: ffffffff82068cea
[   74.730369] RBP: ffff88022fb03d70 R08: 0000000000000000 R09: ffffffff815d26d0
[   74.730371] R10: 0000000000000000 R11: ffffffffa0161ca0 R12: 0000000000000001
[   74.730373] R13: ffff880212448008 R14: ffff880212448330 R15: 0000000000000000
[   74.730376] FS:  0000000000000000(0000) GS:ffff88022fb00000(0000) knlGS:0000000000000000
[   74.730378] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   74.730380] CR2: 000055edcbec9000 CR3: 0000000002210001 CR4: 00000000000606e0
[   74.730382] Call Trace:
[   74.730385]  <IRQ>
[   74.730397]  drm_get_last_vbltimestamp+0x36/0x50
[   74.730401]  drm_update_vblank_count+0x64/0x240
[   74.730409]  drm_crtc_accurate_vblank_count+0x41/0x90
[   74.730453]  display_pipe_crc_irq_handler+0x176/0x220 [i915]
[   74.730497]  i9xx_pipe_crc_irq_handler+0xfe/0x150 [i915]
[   74.730537]  ironlake_irq_handler+0x618/0xa30 [i915]
[   74.730548]  __handle_irq_event_percpu+0x3c/0x340
[   74.730556]  handle_irq_event_percpu+0x1b/0x50
[   74.730561]  handle_irq_event+0x2f/0x50
[   74.730566]  handle_edge_irq+0xe4/0x1b0
[   74.730572]  handle_irq+0x11/0x20
[   74.730576]  do_IRQ+0x5e/0x120
[   74.730584]  common_interrupt+0x84/0x84
[   74.730586]  </IRQ>
[   74.730591] RIP: 0010:cpuidle_enter_state+0xaa/0x350
[   74.730593] RSP: 0018:ffffc9000008beb8 EFLAGS: 00000212 ORIG_RAX: ffffffffffffffde
[   74.730597] RAX: ffff880226b80040 RBX: 000000000031fc3e RCX: 0000000000000001
[   74.730599] RDX: 0000000000000000 RSI: ffffffff8210fb59 RDI: ffffffff820c02e7
[   74.730601] RBP: 0000000000000004 R08: 00000000000040af R09: 0000000000000018
[   74.730603] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000004
[   74.730606] R13: ffffe8ffffd00430 R14: 0000001166120bf4 R15: ffffffff82294460
[   74.730621]  ? cpuidle_enter_state+0xa6/0x350
[   74.730629]  do_idle+0x188/0x1d0
[   74.730636]  cpu_startup_entry+0x14/0x20
[   74.730641]  start_secondary+0x129/0x160
[   74.730646]  secondary_startup_64+0xa5/0xb0
[   74.730660] Code: e1 48 c7 c2 b8 7d 0e 82 be 01 00 00 00 48 c7 c7 ea 8c 06 82 e8 64 ec ff ff 48 8b 83 c8 07 00 00 48 83 78 28 00 0f 84 e2 fe ff ff <0f> 0b 45 31 ed e9 db fe ff ff 41 b8 d3 4d 62 10 89 c8 6a 03 41
[   74.730754] ---[ end trace 14b1345705b68565 ]---

Changes since v1:
- Don't try to apply CRC workaround when enabling pipe, it should already be enabled.
Changes since v2:
- Make crc functions for !DEBUGFS case inline.
- Pass intel_crtc to crc functions.
- Add comments to callsites.
Changes since v3:
- Cache selected source to pipe_crc->source.
- Set pipe_crc->skipped to MIN_INT during disable to close a race condition.
Changes since v4:
- Handle fallout from setting pipe_crc->source in irq handler.

Cc: Marta Löfstedt <marta.lofstedt@intel.com>
Reported-by: Marta Löfstedt <marta.lofstedt@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105185
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180308120202.52446-1-maarten.lankhorst@linux.intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

drivers/gpu/drm/i915/i915_irq.c

@@ -1627,7 +1627,7 @@ static void display_pipe_crc_irq_handler(struct drm_i915_private *dev_priv,
 	int head, tail;
 
 	spin_lock(&pipe_crc->lock);
-	if (pipe_crc->source) {
+	if (pipe_crc->source && !crtc->base.crc.opened) {
 		if (!pipe_crc->entries) {
 			spin_unlock(&pipe_crc->lock);
 			DRM_DEBUG_KMS("spurious interrupt\n");
@@ -1667,7 +1667,7 @@ static void display_pipe_crc_irq_handler(struct drm_i915_private *dev_priv,
 		 * On GEN8+ sometimes the second CRC is bonkers as well, so
 		 * don't trust that one either.
 		 */
-		if (pipe_crc->skipped == 0 ||
+		if (pipe_crc->skipped <= 0 ||
 		    (INTEL_GEN(dev_priv) >= 8 && pipe_crc->skipped == 1)) {
 			pipe_crc->skipped++;
 			spin_unlock(&pipe_crc->lock);

drivers/gpu/drm/i915/intel_display.c

@@ -12145,6 +12145,9 @@ static void intel_update_crtc(struct drm_crtc *crtc,
 	if (modeset) {
 		update_scanline_offset(intel_crtc);
 		dev_priv->display.crtc_enable(pipe_config, state);
+
+		/* vblanks work again, re-enable pipe CRC. */
+		intel_crtc_enable_pipe_crc(intel_crtc);
 	} else {
 		intel_pre_plane_update(to_intel_crtc_state(old_crtc_state),
 				       pipe_config);
@@ -12325,6 +12328,13 @@ static void intel_atomic_commit_tail(struct drm_atomic_state *state)
 
 		if (old_crtc_state->active) {
 			intel_crtc_disable_planes(crtc, old_crtc_state->plane_mask);
+
+			/*
+			 * We need to disable pipe CRC before disabling the pipe,
+			 * or we race against vblank off.
+			 */
+			intel_crtc_disable_pipe_crc(intel_crtc);
+
 			dev_priv->display.crtc_disable(to_intel_crtc_state(old_crtc_state), state);
 			intel_crtc->active = false;
 			intel_fbc_disable(intel_crtc);

drivers/gpu/drm/i915/intel_drv.h

@@ -2136,8 +2136,17 @@ int intel_pipe_crc_create(struct drm_minor *minor);
 #ifdef CONFIG_DEBUG_FS
 int intel_crtc_set_crc_source(struct drm_crtc *crtc, const char *source_name,
 			      size_t *values_cnt);
+void intel_crtc_disable_pipe_crc(struct intel_crtc *crtc);
+void intel_crtc_enable_pipe_crc(struct intel_crtc *crtc);
 #else
 #define intel_crtc_set_crc_source NULL
+static inline void intel_crtc_disable_pipe_crc(struct intel_crtc *crtc)
+{
+}
+
+static inline void intel_crtc_enable_pipe_crc(struct intel_crtc *crtc)
+{
+}
 #endif
 extern const struct file_operations i915_display_crc_ctl_fops;
 #endif /* __INTEL_DRV_H__ */

drivers/gpu/drm/i915/intel_pipe_crc.c

@@ -569,7 +569,8 @@ unlock:
 static int ivb_pipe_crc_ctl_reg(struct drm_i915_private *dev_priv,
 				enum pipe pipe,
 				enum intel_pipe_crc_source *source,
-				uint32_t *val)
+				uint32_t *val,
+				bool set_wa)
 {
 	if (*source == INTEL_PIPE_CRC_SOURCE_AUTO)
 		*source = INTEL_PIPE_CRC_SOURCE_PF;
@@ -582,7 +583,7 @@ static int ivb_pipe_crc_ctl_reg(struct drm_i915_private *dev_priv,
 		*val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_SPRITE_IVB;
 		break;
 	case INTEL_PIPE_CRC_SOURCE_PF:
-		if ((IS_HASWELL(dev_priv) ||
+		if (set_wa && (IS_HASWELL(dev_priv) ||
 		     IS_BROADWELL(dev_priv)) && pipe == PIPE_A)
 			hsw_pipe_A_crc_wa(dev_priv, true);
 
@@ -600,7 +601,8 @@ static int ivb_pipe_crc_ctl_reg(struct drm_i915_private *dev_priv,
 
 static int get_new_crc_ctl_reg(struct drm_i915_private *dev_priv,
 			       enum pipe pipe,
-			       enum intel_pipe_crc_source *source, u32 *val)
+			       enum intel_pipe_crc_source *source, u32 *val,
+			       bool set_wa)
 {
 	if (IS_GEN2(dev_priv))
 		return i8xx_pipe_crc_ctl_reg(source, val);
@@ -611,7 +613,7 @@ static int get_new_crc_ctl_reg(struct drm_i915_private *dev_priv,
 	else if (IS_GEN5(dev_priv) || IS_GEN6(dev_priv))
 		return ilk_pipe_crc_ctl_reg(source, val);
 	else
-		return ivb_pipe_crc_ctl_reg(dev_priv, pipe, source, val);
+		return ivb_pipe_crc_ctl_reg(dev_priv, pipe, source, val, set_wa);
 }
 
 static int pipe_crc_set_source(struct drm_i915_private *dev_priv,
@@ -636,7 +638,7 @@ static int pipe_crc_set_source(struct drm_i915_private *dev_priv,
 		return -EIO;
 	}
 
-	ret = get_new_crc_ctl_reg(dev_priv, pipe, &source, &val);
+	ret = get_new_crc_ctl_reg(dev_priv, pipe, &source, &val, true);
 	if (ret != 0)
 		goto out;
 
@@ -916,7 +918,7 @@ int intel_pipe_crc_create(struct drm_minor *minor)
 int intel_crtc_set_crc_source(struct drm_crtc *crtc, const char *source_name,
 			      size_t *values_cnt)
 {
-	struct drm_i915_private *dev_priv = crtc->dev->dev_private;
+	struct drm_i915_private *dev_priv = to_i915(crtc->dev);
 	struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[crtc->index];
 	enum intel_display_power_domain power_domain;
 	enum intel_pipe_crc_source source;
@@ -934,10 +936,11 @@ int intel_crtc_set_crc_source(struct drm_crtc *crtc, const char *source_name,
 		return -EIO;
 	}
 
-	ret = get_new_crc_ctl_reg(dev_priv, crtc->index, &source, &val);
+	ret = get_new_crc_ctl_reg(dev_priv, crtc->index, &source, &val, true);
 	if (ret != 0)
 		goto out;
 
+	pipe_crc->source = source;
 	I915_WRITE(PIPE_CRC_CTL(crtc->index), val);
 	POSTING_READ(PIPE_CRC_CTL(crtc->index));
 
@@ -959,3 +962,39 @@ out:
 
 	return ret;
 }
+
+void intel_crtc_enable_pipe_crc(struct intel_crtc *intel_crtc)
+{
+	struct drm_crtc *crtc = &intel_crtc->base;
+	struct drm_i915_private *dev_priv = to_i915(crtc->dev);
+	struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[crtc->index];
+	u32 val = 0;
+
+	if (!crtc->crc.opened)
+		return;
+
+	if (get_new_crc_ctl_reg(dev_priv, crtc->index, &pipe_crc->source, &val, false) < 0)
+		return;
+
+	/* Don't need pipe_crc->lock here, IRQs are not generated. */
+	pipe_crc->skipped = 0;
+
+	I915_WRITE(PIPE_CRC_CTL(crtc->index), val);
+	POSTING_READ(PIPE_CRC_CTL(crtc->index));
+}
+
+void intel_crtc_disable_pipe_crc(struct intel_crtc *intel_crtc)
+{
+	struct drm_crtc *crtc = &intel_crtc->base;
+	struct drm_i915_private *dev_priv = to_i915(crtc->dev);
+	struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[crtc->index];
+
+	/* Swallow crc's until we stop generating them. */
+	spin_lock_irq(&pipe_crc->lock);
+	pipe_crc->skipped = INT_MIN;
+	spin_unlock_irq(&pipe_crc->lock);
+
+	I915_WRITE(PIPE_CRC_CTL(crtc->index), 0);
+	POSTING_READ(PIPE_CRC_CTL(crtc->index));
+	synchronize_irq(dev_priv->drm.irq);
+}