[PATCH] drm/radeon: Use a local mutex for bind/unbind protection

[Takashi Iwai <tiwai@xxxxxxx>]

We used drm_modeset_lock_all() for protecting the audio component
bind/unbind operations against the notification, but it seems leading
to kernel WARNING and Oops.  Moreover, the use of
drm_modeset_lock_all() is rather an overkill only for this
protection.

This patch introduces a new mutex that protects just the bind/unbind
and the notify calls and replaces the drm_modeset_lock with it.

Fixes: 34d84636e5e0 ("drm/radeon: Add HD-audio component notifier support (v4)")
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1569
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
 drivers/gpu/drm/radeon/radeon.h        |  1 +
 drivers/gpu/drm/radeon/radeon_audio.c  | 21 ++++++++++++---------
 drivers/gpu/drm/radeon/radeon_device.c |  1 +
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index d82424525f5a..2e7161acd443 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -1799,6 +1799,7 @@ struct r600_audio {
 	struct radeon_audio_basic_funcs *funcs;
 	struct drm_audio_component *component;
 	bool component_registered;
+	struct mutex component_mutex;
 };
 
 /*
diff --git a/drivers/gpu/drm/radeon/radeon_audio.c b/drivers/gpu/drm/radeon/radeon_audio.c
index 4ceb90556127..71b67d4efe08 100644
--- a/drivers/gpu/drm/radeon/radeon_audio.c
+++ b/drivers/gpu/drm/radeon/radeon_audio.c
@@ -181,8 +181,7 @@ static struct radeon_audio_funcs dce6_dp_funcs = {
 	.dpms = evergreen_dp_enable,
 };
 
-static void radeon_audio_component_notify(struct drm_audio_component *acomp,
-					  int port);
+static void radeon_audio_component_notify(struct radeon_device *rdev, int port);
 
 static void radeon_audio_enable(struct radeon_device *rdev,
 				struct r600_audio_pin *pin, u8 enable_mask)
@@ -212,7 +211,7 @@ static void radeon_audio_enable(struct radeon_device *rdev,
 	if (rdev->audio.funcs->enable)
 		rdev->audio.funcs->enable(rdev, pin, enable_mask);
 
-	radeon_audio_component_notify(rdev->audio.component, pin->id);
+	radeon_audio_component_notify(rdev, pin->id);
 }
 
 static void radeon_audio_interface_init(struct radeon_device *rdev)
@@ -731,12 +730,16 @@ unsigned int radeon_audio_decode_dfs_div(unsigned int div)
 /*
  * Audio component support
  */
-static void radeon_audio_component_notify(struct drm_audio_component *acomp,
-					  int port)
+static void radeon_audio_component_notify(struct radeon_device *rdev, int port)
 {
+	struct drm_audio_component *acomp;
+
+	mutex_lock(&rdev->audio.component_mutex);
+	acomp = rdev->audio.component;
 	if (acomp && acomp->audio_ops && acomp->audio_ops->pin_eld_notify)
 		acomp->audio_ops->pin_eld_notify(acomp->audio_ops->audio_ptr,
 						 port, -1);
+	mutex_unlock(&rdev->audio.component_mutex);
 }
 
 static int radeon_audio_component_get_eld(struct device *kdev, int port,
@@ -787,11 +790,11 @@ static int radeon_audio_component_bind(struct device *kdev,
 	if (WARN_ON(!device_link_add(hda_kdev, kdev, DL_FLAG_STATELESS)))
 		return -ENOMEM;
 
-	drm_modeset_lock_all(dev);
+	mutex_lock(&rdev->audio.component_mutex);
 	acomp->ops = &radeon_audio_component_ops;
 	acomp->dev = kdev;
 	rdev->audio.component = acomp;
-	drm_modeset_unlock_all(dev);
+	mutex_unlock(&rdev->audio.component_mutex);
 
 	return 0;
 }
@@ -805,11 +808,11 @@ static void radeon_audio_component_unbind(struct device *kdev,
 
 	device_link_remove(hda_kdev, kdev);
 
-	drm_modeset_lock_all(dev);
+	mutex_lock(&rdev->audio.component_mutex);
 	rdev->audio.component = NULL;
 	acomp->ops = NULL;
 	acomp->dev = NULL;
-	drm_modeset_unlock_all(dev);
+	mutex_unlock(&rdev->audio.component_mutex);
 }
 
 static const struct component_ops radeon_audio_component_bind_ops = {
diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 17bfbbe906c8..2e13ce2b65d3 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1312,6 +1312,7 @@ int radeon_device_init(struct radeon_device *rdev,
 	mutex_init(&rdev->pm.mutex);
 	mutex_init(&rdev->gpu_clock_mutex);
 	mutex_init(&rdev->srbm_mutex);
+	mutex_init(&rdev->audio.component_mutex);
 	init_rwsem(&rdev->pm.mclk_lock);
 	init_rwsem(&rdev->exclusive_lock);
 	init_waitqueue_head(&rdev->irq.vblank_queue);
-- 
2.35.3