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

1 files changed, 21 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 2483447ff8dc..305557e1942a 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/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);