[PATCH v2 1/3] drm/i915/hda: Add audio component stub

[Imre Deak <imre.deak@intel.com>]

User may pass nomodeset or i915.modeset=0 option to disable i915 KMS
explicitly.  Although this itself works fine, it breaks the weak
dependency the HD-audio driver requires, and it's the reason the
delayed component binding isn't implemented in HD-audio.  Since i915
doesn't notify its disablement, HD-audio would be blocked
unnecessarily endlessly, waiting for the bind with i915.

This patch introduces a stub audio component binding when i915 driver
is loaded with KMS off like the boot options above.  Then i915 driver
still registers the slave component but with the new "disabled" ops
flag, so that the master component (HD-audio) can know clearly the
slave state.

v2:
- Fail the probe in case component registration fails, instead of
  suppressing the error. (Ville)
- Register the component only for the real PCI device function.

CC: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 drivers/gpu/drm/i915/i915_drv.c    | 51 +++++++++++++++++++++++-------------
 drivers/gpu/drm/i915/intel_audio.c | 53 ++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h   |  2 ++
 include/drm/i915_component.h       |  5 ++++
 4 files changed, 93 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 5ae7960..b127810 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1016,12 +1016,6 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	struct intel_device_info *intel_info =
 		(struct intel_device_info *) ent->driver_data;
 
-	if (IS_PRELIMINARY_HW(intel_info) && !i915.preliminary_hw_support) {
-		DRM_INFO("This hardware requires preliminary hardware support.\n"
-			 "See CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT, and/or modparam preliminary_hw_support\n");
-		return -ENODEV;
-	}
-
 	/* Only bind to function 0 of the device. Early generations
 	 * used function 1 as a placeholder for multi-head. This causes
 	 * us confusion instead, especially on the systems where both
@@ -1030,6 +1024,29 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (PCI_FUNC(pdev->devfn))
 		return -ENODEV;
 
+	if (!(driver.driver_features & DRIVER_MODESET)) {
+		int ret;
+
+		/*
+		 * Notify the HDA driver so that it doesn't block waiting for
+		 * i915 to become ready.
+		 */
+		ret = i915_audio_component_stub_init(&pdev->dev);
+		if (ret)
+			return ret;
+
+		/* Silently fail loading to not upset userspace. */
+		DRM_DEBUG_DRIVER("KMS and UMS disabled.\n");
+
+		return 0;
+	}
+
+	if (IS_PRELIMINARY_HW(intel_info) && !i915.preliminary_hw_support) {
+		DRM_INFO("This hardware requires preliminary hardware support.\n"
+			 "See CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT, and/or modparam preliminary_hw_support\n");
+		return -ENODEV;
+	}
+
 	/*
 	 * apple-gmux is needed on dual GPU MacBook Pro
 	 * to probe the panel if we're the inactive GPU.
@@ -1045,8 +1062,15 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 static void
 i915_pci_remove(struct pci_dev *pdev)
 {
-	struct drm_device *dev = pci_get_drvdata(pdev);
+	struct drm_device *dev;
 
+	if (!(driver.driver_features & DRIVER_MODESET)) {
+		i915_audio_component_stub_cleanup(&pdev->dev);
+
+		return;
+	}
+
+	dev = pci_get_drvdata(pdev);
 	drm_put_dev(dev);
 }
 
@@ -1767,24 +1791,15 @@ static int __init i915_init(void)
 	if (vgacon_text_force() && i915.modeset == -1)
 		driver.driver_features &= ~DRIVER_MODESET;
 
-	if (!(driver.driver_features & DRIVER_MODESET)) {
-		/* Silently fail loading to not upset userspace. */
-		DRM_DEBUG_DRIVER("KMS and UMS disabled.\n");
-		return 0;
-	}
-
 	if (i915.nuclear_pageflip)
 		driver.driver_features |= DRIVER_ATOMIC;
 
-	return drm_pci_init(&driver, &i915_pci_driver);
+	return pci_register_driver(&i915_pci_driver);
 }
 
 static void __exit i915_exit(void)
 {
-	if (!(driver.driver_features & DRIVER_MODESET))
-		return; /* Never loaded a driver. */
-
-	drm_pci_exit(&driver, &i915_pci_driver);
+	pci_unregister_driver(&i915_pci_driver);
 }
 
 module_init(i915_init);
diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
index b9329c2..603b3fe 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -824,3 +824,56 @@ void i915_audio_component_cleanup(struct drm_i915_private *dev_priv)
 	component_del(dev_priv->dev->dev, &i915_audio_component_bind_ops);
 	dev_priv->audio_component_registered = false;
 }
+
+static const struct i915_audio_component_ops i915_audio_component_stub_ops = {
+	.owner		= THIS_MODULE,
+	.disabled	= true,
+};
+
+static int i915_audio_component_stub_bind(struct device *i915_stub_dev,
+					  struct device *hda_dev, void *data)
+{
+	struct i915_audio_component *acomp = data;
+
+	if (WARN_ON(acomp->ops || acomp->dev))
+		return -EEXIST;
+
+	acomp->ops = &i915_audio_component_stub_ops;
+	acomp->dev = i915_stub_dev;
+
+	return 0;
+}
+
+static void i915_audio_component_stub_unbind(struct device *i915_stub_dev,
+					     struct device *hda_dev, void *data)
+{
+	struct i915_audio_component *acomp = data;
+
+	acomp->ops = NULL;
+	acomp->dev = NULL;
+}
+
+static const struct component_ops i915_audio_component_stub_bind_ops = {
+	.bind	= i915_audio_component_stub_bind,
+	.unbind	= i915_audio_component_stub_unbind,
+};
+
+static const struct file_operations component_stub_dev_ops = {
+	.owner = THIS_MODULE,
+};
+
+int i915_audio_component_stub_init(struct device *dev)
+{
+	int ret;
+
+	ret = component_add(dev, &i915_audio_component_stub_bind_ops);
+	if (ret < 0)
+		DRM_ERROR("failed to add audio stub component (%d)\n", ret);
+
+	return ret;
+}
+
+void i915_audio_component_stub_cleanup(struct device *dev)
+{
+	component_del(dev, &i915_audio_component_stub_bind_ops);
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 0a9c10d..a828e00 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1111,6 +1111,8 @@ void intel_audio_codec_enable(struct intel_encoder *encoder);
 void intel_audio_codec_disable(struct intel_encoder *encoder);
 void i915_audio_component_init(struct drm_i915_private *dev_priv);
 void i915_audio_component_cleanup(struct drm_i915_private *dev_priv);
+int i915_audio_component_stub_init(struct device *dev);
+void i915_audio_component_stub_cleanup(struct device *dev);
 
 /* intel_display.c */
 void intel_update_rawclk(struct drm_i915_private *dev_priv);
diff --git a/include/drm/i915_component.h b/include/drm/i915_component.h
index b46fa0e..33da85a 100644
--- a/include/drm/i915_component.h
+++ b/include/drm/i915_component.h
@@ -39,6 +39,11 @@ struct i915_audio_component_ops {
 	 */
 	struct module *owner;
 	/**
+	 * @disabled: i915 driver loaded with modeset=0, the services provided
+	 * via the audio component interface are not available.
+	 */
+	bool disabled;
+	/**
 	 * @get_power: get the POWER_DOMAIN_AUDIO power well
 	 *
 	 * Request the power well to be turned on.
-- 
2.5.0

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