[PATCH 5/6] drm/i915: Do not call modeset related functions when display is disabled

[José Roberto de Souza]

No need to run i915_load_modeset_init() when num_pipes == 0 also
kms depends on things initialized in i915_load_modeset_init() so not
initializing it too. fbdev and audio have guards against
num_pipes == 0 but lets move it to the if block to make it explicit
to readers.

Also as planes, CRTCs, encoders and connectors are not being added
it is necessary to unset the MODESET driver feature otherwise it
will crash when registering driver in drm, also disabling ATOMIC as
do not make sense have ATOMIC and do not have MODESET.

There is more modeset/display calls that still needs to be removed,
this is a initial work.

Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 69 ++++++++++++++++++++-------------
 1 file changed, 41 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index aacb467fe3ea..e109815cfa51 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1248,23 +1248,26 @@ static void i915_driver_register(struct drm_i915_private *dev_priv)
 	if (IS_GEN5(dev_priv))
 		intel_gpu_ips_init(dev_priv);
 
-	intel_audio_init(dev_priv);
+	if (INTEL_INFO(dev_priv)->num_pipes) {
+		intel_audio_init(dev_priv);
 
-	/*
-	 * Some ports require correctly set-up hpd registers for detection to
-	 * work properly (leading to ghost connected connector status), e.g. VGA
-	 * on gm45.  Hence we can only set up the initial fbdev config after hpd
-	 * irqs are fully enabled. We do it last so that the async config
-	 * cannot run before the connectors are registered.
-	 */
-	intel_fbdev_initial_config_async(dev);
+		/*
+		 * Some ports require correctly set-up hpd registers for
+		 * detection to work properly (leading to ghost connected
+		 * connector status), e.g. VGA on gm45.  Hence we can only set
+		 * up the initial fbdev config after hpd irqs are fully enabled.
+		 * We do it last so that the async config cannot run before the
+		 * connectors are registered.
+		 */
+		intel_fbdev_initial_config_async(dev);
 
-	/*
-	 * We need to coordinate the hotplugs with the asynchronous fbdev
-	 * configuration, for which we use the fbdev->async_cookie.
-	 */
-	if (INTEL_INFO(dev_priv)->num_pipes)
+		/*
+		 * We need to coordinate the hotplugs with the asynchronous
+		 * fbdev configuration, for which we use the
+		 * fbdev->async_cookie.
+		 */
 		drm_kms_helper_poll_init(dev);
+	}
 }
 
 /**
@@ -1273,15 +1276,17 @@ static void i915_driver_register(struct drm_i915_private *dev_priv)
  */
 static void i915_driver_unregister(struct drm_i915_private *dev_priv)
 {
-	intel_fbdev_unregister(dev_priv);
-	intel_audio_deinit(dev_priv);
+	if (INTEL_INFO(dev_priv)->num_pipes) {
+		intel_fbdev_unregister(dev_priv);
+		intel_audio_deinit(dev_priv);
 
-	/*
-	 * After flushing the fbdev (incl. a late async config which will
-	 * have delayed queuing of a hotplug event), then flush the hotplug
-	 * events.
-	 */
-	drm_kms_helper_poll_fini(&dev_priv->drm);
+		/*
+		 * After flushing the fbdev (incl. a late async config which
+		 * will have delayed queuing of a hotplug event), then flush the
+		 * hotplug events.
+		 */
+		drm_kms_helper_poll_fini(&dev_priv->drm);
+	}
 
 	intel_gpu_ips_teardown();
 	acpi_video_unregister();
@@ -1333,6 +1338,9 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (!i915_modparams.nuclear_pageflip && match_info->gen < 5)
 		driver.driver_features &= ~DRIVER_ATOMIC;
 
+	if (i915_modparams.disable_display)
+		driver.driver_features &= ~(DRIVER_MODESET | DRIVER_ATOMIC);
+
 	ret = -ENOMEM;
 	dev_priv = kzalloc(sizeof(*dev_priv), GFP_KERNEL);
 	if (dev_priv)
@@ -1387,9 +1395,11 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (ret)
 		goto cleanup_irq;
 
-	ret = i915_load_modeset_init(&dev_priv->drm);
-	if (ret < 0)
-		goto cleanup_gem;
+	if (INTEL_INFO(dev_priv)->num_pipes) {
+		ret = i915_load_modeset_init(&dev_priv->drm);
+		if (ret < 0)
+			goto cleanup_gem;
+	}
 
 	i915_driver_register(dev_priv);
 
@@ -1439,11 +1449,13 @@ void i915_driver_unload(struct drm_device *dev)
 
 	intel_display_power_get(dev_priv, POWER_DOMAIN_INIT);
 
-	drm_atomic_helper_shutdown(dev);
+	if (INTEL_INFO(dev_priv)->num_pipes)
+		drm_atomic_helper_shutdown(dev);
 
 	intel_gvt_cleanup(dev_priv);
 
-	intel_modeset_cleanup_prepare(dev);
+	if (INTEL_INFO(dev_priv)->num_pipes)
+		intel_modeset_cleanup_prepare(dev);
 
 	intel_disable_gt_powersave(dev_priv);
 
@@ -1454,7 +1466,8 @@ void i915_driver_unload(struct drm_device *dev)
 	 */
 	intel_irq_uninstall(dev_priv);
 
-	intel_modeset_cleanup(dev);
+	if (INTEL_INFO(dev_priv)->num_pipes)
+		intel_modeset_cleanup(dev);
 
 	intel_cleanup_gt_powersave(dev_priv);
 
-- 
2.18.0