drm/nouveau: Add HD-audio component notifier support

This patch adds the support for the notification of HD-audio hotplug
via the already existing drm_audio_component framework.  This allows
us more reliable hotplug notification and ELD transfer without
accessing HD-audio bus; it's more efficient, and more importantly, it
works without waking up the runtime PM.

The implementation is rather simplistic: nouveau driver provides the
get_eld ops for HD-audio, and it notifies the audio hotplug via
pin_eld_notify callback upon each nv50_audio_enable() and _disable()
call.  As the HD-audio pin assignment seems corresponding to the CRTC,
the crtc->index number is passed directly as the zero-based port
number.

The bind and unbind callbacks handle the device-link so that it
assures the PM call order.

Link: https://lore.kernel.org/r/20190722143815.7339-3-tiwai@suse.deReviewed-by: Lyude Paul <lyude@redhat.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/Kconfig

@@ -17,6 +17,7 @@ config DRM_NOUVEAU
 	select INPUT if ACPI && X86
 	select THERMAL if ACPI && X86
 	select ACPI_VIDEO if ACPI && X86
+	select SND_HDA_COMPONENT if SND_HDA_CORE
 	help
 	  Choose this option for open-source NVIDIA support.
 

drivers/gpu/drm/nouveau/dispnv50/disp.c

@@ -29,6 +29,7 @@
 
 #include <linux/dma-mapping.h>
 #include <linux/hdmi.h>
+#include <linux/component.h>
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_dp_helper.h>
@@ -476,12 +477,113 @@ nv50_dac_create(struct drm_connector *connector, struct dcb_output *dcbe)
 	return 0;
 }
 
+/*
+ * audio component binding for ELD notification
+ */
+static void
+nv50_audio_component_eld_notify(struct drm_audio_component *acomp, int port)
+{
+	if (acomp && acomp->audio_ops && acomp->audio_ops->pin_eld_notify)
+		acomp->audio_ops->pin_eld_notify(acomp->audio_ops->audio_ptr,
+						 port, -1);
+}
+
+static int
+nv50_audio_component_get_eld(struct device *kdev, int port, int pipe,
+			     bool *enabled, unsigned char *buf, int max_bytes)
+{
+	struct drm_device *drm_dev = dev_get_drvdata(kdev);
+	struct nouveau_drm *drm = nouveau_drm(drm_dev);
+	struct drm_encoder *encoder;
+	struct nouveau_encoder *nv_encoder;
+	struct nouveau_connector *nv_connector;
+	struct nouveau_crtc *nv_crtc;
+	int ret = 0;
+
+	*enabled = false;
+	drm_for_each_encoder(encoder, drm->dev) {
+		nv_encoder = nouveau_encoder(encoder);
+		nv_connector = nouveau_encoder_connector_get(nv_encoder);
+		nv_crtc = nouveau_crtc(encoder->crtc);
+		if (!nv_connector || !nv_crtc || nv_crtc->index != port)
+			continue;
+		*enabled = drm_detect_monitor_audio(nv_connector->edid);
+		if (*enabled) {
+			ret = drm_eld_size(nv_connector->base.eld);
+			memcpy(buf, nv_connector->base.eld,
+			       min(max_bytes, ret));
+		}
+		break;
+	}
+	return ret;
+}
+
+static const struct drm_audio_component_ops nv50_audio_component_ops = {
+	.get_eld = nv50_audio_component_get_eld,
+};
+
+static int
+nv50_audio_component_bind(struct device *kdev, struct device *hda_kdev,
+			  void *data)
+{
+	struct drm_device *drm_dev = dev_get_drvdata(kdev);
+	struct nouveau_drm *drm = nouveau_drm(drm_dev);
+	struct drm_audio_component *acomp = data;
+
+	if (WARN_ON(!device_link_add(hda_kdev, kdev, DL_FLAG_STATELESS)))
+		return -ENOMEM;
+
+	drm_modeset_lock_all(drm_dev);
+	acomp->ops = &nv50_audio_component_ops;
+	acomp->dev = kdev;
+	drm->audio.component = acomp;
+	drm_modeset_unlock_all(drm_dev);
+	return 0;
+}
+
+static void
+nv50_audio_component_unbind(struct device *kdev, struct device *hda_kdev,
+			    void *data)
+{
+	struct drm_device *drm_dev = dev_get_drvdata(kdev);
+	struct nouveau_drm *drm = nouveau_drm(drm_dev);
+	struct drm_audio_component *acomp = data;
+
+	drm_modeset_lock_all(drm_dev);
+	drm->audio.component = NULL;
+	acomp->ops = NULL;
+	acomp->dev = NULL;
+	drm_modeset_unlock_all(drm_dev);
+}
+
+static const struct component_ops nv50_audio_component_bind_ops = {
+	.bind   = nv50_audio_component_bind,
+	.unbind = nv50_audio_component_unbind,
+};
+
+static void
+nv50_audio_component_init(struct nouveau_drm *drm)
+{
+	if (!component_add(drm->dev->dev, &nv50_audio_component_bind_ops))
+		drm->audio.component_registered = true;
+}
+
+static void
+nv50_audio_component_fini(struct nouveau_drm *drm)
+{
+	if (drm->audio.component_registered) {
+		component_del(drm->dev->dev, &nv50_audio_component_bind_ops);
+		drm->audio.component_registered = false;
+	}
+}
+
 /******************************************************************************
  * Audio
  *****************************************************************************/
 static void
 nv50_audio_disable(struct drm_encoder *encoder, struct nouveau_crtc *nv_crtc)
 {
+	struct nouveau_drm *drm = nouveau_drm(encoder->dev);
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nv50_disp *disp = nv50_disp(encoder->dev);
 	struct {
@@ -496,11 +598,14 @@ nv50_audio_disable(struct drm_encoder *encoder, struct nouveau_crtc *nv_crtc)
 	};
 
 	nvif_mthd(&disp->disp->object, 0, &args, sizeof(args));
+
+	nv50_audio_component_eld_notify(drm->audio.component, nv_crtc->index);
 }
 
 static void
 nv50_audio_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
 {
+	struct nouveau_drm *drm = nouveau_drm(encoder->dev);
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_crtc *nv_crtc = nouveau_crtc(encoder->crtc);
 	struct nouveau_connector *nv_connector;
@@ -527,6 +632,8 @@ nv50_audio_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
 
 	nvif_mthd(&disp->disp->object, 0, &args,
 		  sizeof(args.base) + drm_eld_size(args.data));
+
+	nv50_audio_component_eld_notify(drm->audio.component, nv_crtc->index);
 }
 
 /******************************************************************************
@@ -2296,6 +2403,8 @@ nv50_display_destroy(struct drm_device *dev)
 {
 	struct nv50_disp *disp = nv50_disp(dev);
 
+	nv50_audio_component_fini(nouveau_drm(dev));
+
 	nv50_core_del(&disp->core);
 
 	nouveau_bo_unmap(disp->sync);
@@ -2444,6 +2553,8 @@ nv50_display_create(struct drm_device *dev)
 	/* Disable vblank irqs aggressively for power-saving, safe on nv50+ */
 	dev->vblank_disable_immediate = true;
 
+	nv50_audio_component_init(drm);
+
 out:
 	if (ret)
 		nv50_display_destroy(dev);

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -58,6 +58,8 @@
 #include <drm/ttm/ttm_module.h>
 #include <drm/ttm/ttm_page_alloc.h>
 
+#include <drm/drm_audio_component.h>
+
 #include "uapi/drm/nouveau_drm.h"
 
 struct nouveau_channel;
@@ -211,6 +213,11 @@ struct nouveau_drm {
 	struct nouveau_svm *svm;
 
 	struct nouveau_dmem *dmem;
+
+	struct {
+		struct drm_audio_component *component;
+		bool component_registered;
+	} audio;
 };
 
 static inline struct nouveau_drm *