drm/i915: skip display initialization when there is no display

Display features should not be initialized or de-initialized when there
is no display. Skip modeset initialization, output setup, plane, crtc,
encoder, connector registration, display cdclk and rawclk
initialization, display core initialization, etc.

Skip the functionality at as high level as possible, and remove any
redundant checks. If the functionality is conditional to *other* display
checks, do not add more. If the un-initialization has checks for
initialization, do not add more.

We explicitly do not care about any GMCH/VLV/CHV code paths, as they've
always had and will have display.
Reviewed-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210408203150.237947-3-jose.souza@intel.com

drivers/gpu/drm/i915/display/intel_display.c

@@ -1335,6 +1335,9 @@ u32 intel_plane_fb_max_stride(struct drm_i915_private *dev_priv,
 	struct intel_crtc *crtc;
 	struct intel_plane *plane;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return 0;
+
 	/*
 	 * We assume the primary plane for pipe A has
 	 * the highest stride limits of them all,
@@ -3838,6 +3841,9 @@ int intel_display_suspend(struct drm_device *dev)
 	struct drm_atomic_state *state;
 	int ret;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return 0;
+
 	state = drm_atomic_helper_suspend(dev);
 	ret = PTR_ERR_OR_ZERO(state);
 	if (ret)
@@ -11429,6 +11435,9 @@ static const struct drm_mode_config_funcs intel_mode_funcs = {
  */
 void intel_init_display_hooks(struct drm_i915_private *dev_priv)
 {
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	intel_init_cdclk_hooks(dev_priv);
 	intel_init_audio_hooks(dev_priv);
 
@@ -11471,8 +11480,12 @@ void intel_init_display_hooks(struct drm_i915_private *dev_priv)
 
 void intel_modeset_init_hw(struct drm_i915_private *i915)
 {
-	struct intel_cdclk_state *cdclk_state =
-		to_intel_cdclk_state(i915->cdclk.obj.state);
+	struct intel_cdclk_state *cdclk_state;
+
+	if (!HAS_DISPLAY(i915))
+		return;
+
+	cdclk_state = to_intel_cdclk_state(i915->cdclk.obj.state);
 
 	intel_update_cdclk(i915);
 	intel_dump_cdclk_config(&i915->cdclk.hw, "Current CDCLK");
@@ -11788,6 +11801,9 @@ int intel_modeset_init_noirq(struct drm_i915_private *i915)
 	/* FIXME: completely on the wrong abstraction layer */
 	intel_power_domains_init_hw(i915, false);
 
+	if (!HAS_DISPLAY(i915))
+		return 0;
+
 	intel_csr_ucode_init(i915);
 
 	i915->modeset_wq = alloc_ordered_workqueue("i915_modeset", 0);
@@ -11838,6 +11854,9 @@ int intel_modeset_init_nogem(struct drm_i915_private *i915)
 	struct intel_crtc *crtc;
 	int ret;
 
+	if (!HAS_DISPLAY(i915))
+		return 0;
+
 	intel_init_pm(i915);
 
 	intel_panel_sanitize_ssc(i915);
@@ -11850,13 +11869,11 @@ int intel_modeset_init_nogem(struct drm_i915_private *i915)
 		    INTEL_NUM_PIPES(i915),
 		    INTEL_NUM_PIPES(i915) > 1 ? "s" : "");
 
-	if (HAS_DISPLAY(i915)) {
-		for_each_pipe(i915, pipe) {
-			ret = intel_crtc_init(i915, pipe);
-			if (ret) {
-				intel_mode_config_cleanup(i915);
-				return ret;
-			}
+	for_each_pipe(i915, pipe) {
+		ret = intel_crtc_init(i915, pipe);
+		if (ret) {
+			intel_mode_config_cleanup(i915);
+			return ret;
 		}
 	}
 
@@ -12791,6 +12808,9 @@ void intel_display_resume(struct drm_device *dev)
 	struct drm_modeset_acquire_ctx ctx;
 	int ret;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	dev_priv->modeset_restore_state = NULL;
 	if (state)
 		state->acquire_ctx = &ctx;
@@ -12840,6 +12860,9 @@ static void intel_hpd_poll_fini(struct drm_i915_private *i915)
 /* part #1: call before irq uninstall */
 void intel_modeset_driver_remove(struct drm_i915_private *i915)
 {
+	if (!HAS_DISPLAY(i915))
+		return;
+
 	flush_workqueue(i915->flip_wq);
 	flush_workqueue(i915->modeset_wq);
 
@@ -12850,6 +12873,9 @@ void intel_modeset_driver_remove(struct drm_i915_private *i915)
 /* part #2: call after irq uninstall */
 void intel_modeset_driver_remove_noirq(struct drm_i915_private *i915)
 {
+	if (!HAS_DISPLAY(i915))
+		return;
+
 	/*
 	 * Due to the hpd irq storm handling the hotplug work can re-arm the
 	 * poll handlers. Hence disable polling after hpd handling is shut down.

drivers/gpu/drm/i915/display/intel_display_power.c

@@ -821,6 +821,9 @@ static void gen9_sanitize_dc_state(struct drm_i915_private *dev_priv)
 {
 	u32 val;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	val = intel_de_read(dev_priv, DC_STATE_EN) & gen9_dc_mask(dev_priv);
 
 	drm_dbg_kms(&dev_priv->drm,
@@ -857,6 +860,9 @@ static void gen9_set_dc_state(struct drm_i915_private *dev_priv, u32 state)
 	u32 val;
 	u32 mask;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	if (drm_WARN_ON_ONCE(&dev_priv->drm,
 			     state & ~dev_priv->csr.allowed_dc_mask))
 		state &= dev_priv->csr.allowed_dc_mask;
@@ -1181,6 +1187,9 @@ static void gen9_disable_dc_states(struct drm_i915_private *dev_priv)
 
 	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	dev_priv->display.get_cdclk(dev_priv, &cdclk_config);
 	/* Can't read out voltage_level so can't use intel_cdclk_changed() */
 	drm_WARN_ON(&dev_priv->drm,
@@ -4533,6 +4542,9 @@ static u32 get_allowed_dc_mask(const struct drm_i915_private *dev_priv,
 	int requested_dc;
 	int max_dc;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return 0;
+
 	if (IS_DG1(dev_priv))
 		max_dc = 3;
 	else if (DISPLAY_VER(dev_priv) >= 12)
@@ -5126,6 +5138,9 @@ static void skl_display_core_init(struct drm_i915_private *dev_priv,
 	/* enable PCH reset handshake */
 	intel_pch_reset_handshake(dev_priv, !HAS_PCH_NOP(dev_priv));
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	/* enable PG1 and Misc I/O */
 	mutex_lock(&power_domains->lock);
 
@@ -5150,6 +5165,9 @@ static void skl_display_core_uninit(struct drm_i915_private *dev_priv)
 	struct i915_power_domains *power_domains = &dev_priv->power_domains;
 	struct i915_power_well *well;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	gen9_disable_dc_states(dev_priv);
 
 	gen9_dbuf_disable(dev_priv);
@@ -5190,6 +5208,9 @@ static void bxt_display_core_init(struct drm_i915_private *dev_priv, bool resume
 	 */
 	intel_pch_reset_handshake(dev_priv, false);
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	/* Enable PG1 */
 	mutex_lock(&power_domains->lock);
 
@@ -5211,6 +5232,9 @@ static void bxt_display_core_uninit(struct drm_i915_private *dev_priv)
 	struct i915_power_domains *power_domains = &dev_priv->power_domains;
 	struct i915_power_well *well;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	gen9_disable_dc_states(dev_priv);
 
 	gen9_dbuf_disable(dev_priv);
@@ -5244,6 +5268,9 @@ static void cnl_display_core_init(struct drm_i915_private *dev_priv, bool resume
 	/* 1. Enable PCH Reset Handshake */
 	intel_pch_reset_handshake(dev_priv, !HAS_PCH_NOP(dev_priv));
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	/* 2-3. */
 	intel_combo_phy_init(dev_priv);
 
@@ -5271,6 +5298,9 @@ static void cnl_display_core_uninit(struct drm_i915_private *dev_priv)
 	struct i915_power_domains *power_domains = &dev_priv->power_domains;
 	struct i915_power_well *well;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	gen9_disable_dc_states(dev_priv);
 
 	/* 1. Disable all display engine functions -> aready done */
@@ -5385,6 +5415,9 @@ static void icl_display_core_init(struct drm_i915_private *dev_priv,
 	/* 1. Enable PCH reset handshake. */
 	intel_pch_reset_handshake(dev_priv, !HAS_PCH_NOP(dev_priv));
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	/* 2. Initialize all combo phys */
 	intel_combo_phy_init(dev_priv);
 
@@ -5429,6 +5462,9 @@ static void icl_display_core_uninit(struct drm_i915_private *dev_priv)
 	struct i915_power_domains *power_domains = &dev_priv->power_domains;
 	struct i915_power_well *well;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	gen9_disable_dc_states(dev_priv);
 
 	/* 1. Disable all display engine functions -> aready done */

drivers/gpu/drm/i915/display/intel_dp.c

@@ -5430,6 +5430,9 @@ void intel_dp_mst_suspend(struct drm_i915_private *dev_priv)
 {
 	struct intel_encoder *encoder;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	for_each_intel_encoder(&dev_priv->drm, encoder) {
 		struct intel_dp *intel_dp;
 
@@ -5450,6 +5453,9 @@ void intel_dp_mst_resume(struct drm_i915_private *dev_priv)
 {
 	struct intel_encoder *encoder;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	for_each_intel_encoder(&dev_priv->drm, encoder) {
 		struct intel_dp *intel_dp;
 		int ret;

drivers/gpu/drm/i915/display/intel_gmbus.c

@@ -845,9 +845,6 @@ int intel_gmbus_setup(struct drm_i915_private *dev_priv)
 	unsigned int pin;
 	int ret;
 
-	if (!HAS_DISPLAY(dev_priv))
-		return 0;
-
 	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
 		dev_priv->gpio_mmio_base = VLV_DISPLAY_BASE;
 	else if (!HAS_GMCH(dev_priv))

drivers/gpu/drm/i915/display/intel_hotplug.c

@@ -595,6 +595,9 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
 {
 	int i;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	for_each_hpd_pin(i) {
 		dev_priv->hotplug.stats[i].count = 0;
 		dev_priv->hotplug.stats[i].state = HPD_ENABLED;
@@ -670,6 +673,9 @@ static void i915_hpd_poll_init_work(struct work_struct *work)
  */
 void intel_hpd_poll_enable(struct drm_i915_private *dev_priv)
 {
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	WRITE_ONCE(dev_priv->hotplug.poll_enabled, true);
 
 	/*
@@ -702,6 +708,9 @@ void intel_hpd_poll_enable(struct drm_i915_private *dev_priv)
  */
 void intel_hpd_poll_disable(struct drm_i915_private *dev_priv)
 {
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	WRITE_ONCE(dev_priv->hotplug.poll_enabled, false);
 	schedule_work(&dev_priv->hotplug.poll_init_work);
 }
@@ -718,6 +727,9 @@ void intel_hpd_init_work(struct drm_i915_private *dev_priv)
 
 void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
 {
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	spin_lock_irq(&dev_priv->irq_lock);
 
 	dev_priv->hotplug.long_port_mask = 0;

drivers/gpu/drm/i915/display/intel_pps.c

@@ -316,6 +316,9 @@ void intel_pps_reset_all(struct drm_i915_private *dev_priv)
 	if (drm_WARN_ON(&dev_priv->drm, !IS_LP(dev_priv)))
 		return;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	/*
 	 * We can't grab pps_mutex here due to deadlock with power_domain
 	 * mutex when power_domain functions are called while holding pps_mutex.
@@ -1376,7 +1379,7 @@ void intel_pps_unlock_regs_wa(struct drm_i915_private *dev_priv)
 	int pps_num;
 	int pps_idx;
 
-	if (HAS_DDI(dev_priv))
+	if (!HAS_DISPLAY(dev_priv) || HAS_DDI(dev_priv))
 		return;
 	/*
 	 * This w/a is needed at least on CPT/PPT, but to be sure apply it

drivers/gpu/drm/i915/i915_drv.c

@@ -973,8 +973,12 @@ static int i915_driver_open(struct drm_device *dev, struct drm_file *file)
  */
 static void i915_driver_lastclose(struct drm_device *dev)
 {
+	struct drm_i915_private *i915 = to_i915(dev);
+
 	intel_fbdev_restore_mode(dev);
-	vga_switcheroo_process_delayed_switch();
+
+	if (HAS_DISPLAY(i915))
+		vga_switcheroo_process_delayed_switch();
 }
 
 static void i915_driver_postclose(struct drm_device *dev, struct drm_file *file)
@@ -994,6 +998,9 @@ static void intel_suspend_encoders(struct drm_i915_private *dev_priv)
 	struct drm_device *dev = &dev_priv->drm;
 	struct intel_encoder *encoder;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	drm_modeset_lock_all(dev);
 	for_each_intel_encoder(dev, encoder)
 		if (encoder->suspend)
@@ -1006,6 +1013,9 @@ static void intel_shutdown_encoders(struct drm_i915_private *dev_priv)
 	struct drm_device *dev = &dev_priv->drm;
 	struct intel_encoder *encoder;
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	drm_modeset_lock_all(dev);
 	for_each_intel_encoder(dev, encoder)
 		if (encoder->shutdown)
@@ -1021,9 +1031,11 @@ void i915_driver_shutdown(struct drm_i915_private *i915)
 
 	i915_gem_suspend(i915);
 
-	drm_kms_helper_poll_disable(&i915->drm);
+	if (HAS_DISPLAY(i915)) {
+		drm_kms_helper_poll_disable(&i915->drm);
 
-	drm_atomic_helper_shutdown(&i915->drm);
+		drm_atomic_helper_shutdown(&i915->drm);
+	}
 
 	intel_dp_mst_suspend(i915);
 
@@ -1087,8 +1099,8 @@ static int i915_drm_suspend(struct drm_device *dev)
 	/* We do a lot of poking in a lot of registers, make sure they work
 	 * properly. */
 	intel_power_domains_disable(dev_priv);
-
-	drm_kms_helper_poll_disable(dev);
+	if (HAS_DISPLAY(dev_priv))
+		drm_kms_helper_poll_disable(dev);
 
 	pci_save_state(pdev);
 
@@ -1235,7 +1247,8 @@ static int i915_drm_resume(struct drm_device *dev)
 	 */
 	intel_runtime_pm_enable_interrupts(dev_priv);
 
-	drm_mode_config_reset(dev);
+	if (HAS_DISPLAY(dev_priv))
+		drm_mode_config_reset(dev);
 
 	i915_gem_resume(dev_priv);
 
@@ -1248,7 +1261,8 @@ static int i915_drm_resume(struct drm_device *dev)
 	intel_display_resume(dev);
 
 	intel_hpd_poll_disable(dev_priv);
-	drm_kms_helper_poll_enable(dev);
+	if (HAS_DISPLAY(dev_priv))
+		drm_kms_helper_poll_enable(dev);
 
 	intel_opregion_resume(dev_priv);
 

drivers/gpu/drm/i915/i915_suspend.c

@@ -87,6 +87,9 @@ void i915_save_display(struct drm_i915_private *dev_priv)
 {
 	struct pci_dev *pdev = to_pci_dev(dev_priv->drm.dev);
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	/* Display arbitration control */
 	if (INTEL_GEN(dev_priv) <= 4)
 		dev_priv->regfile.saveDSPARB = intel_de_read(dev_priv, DSPARB);
@@ -102,6 +105,9 @@ void i915_restore_display(struct drm_i915_private *dev_priv)
 {
 	struct pci_dev *pdev = to_pci_dev(dev_priv->drm.dev);
 
+	if (!HAS_DISPLAY(dev_priv))
+		return;
+
 	intel_restore_swf(dev_priv);
 
 	if (IS_GEN(dev_priv, 4))