[PATCH 1/6] drm/rockchip: Change psr list mutex to spinlock

[Sean Paul]

Since it needs to be taken in the vblank_enable/disable stack,
which is protected by another spinlock. This lock should be
completely uncontested, since it's only taken in find_psr and
register, which is only called on init.

Signed-off-by: Sean Paul <seanpaul at chromium.org>
---
 drivers/gpu/drm/rockchip/rockchip_drm_drv.c |  2 +-
 drivers/gpu/drm/rockchip/rockchip_drm_drv.h |  2 +-
 drivers/gpu/drm/rockchip/rockchip_drm_psr.c | 30 ++++++++++++++++-------------
 3 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index fe89ea5..0f57f3b 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -189,7 +189,7 @@ static int rockchip_drm_load(struct drm_device *drm_dev, unsigned long flags)
 	drm_dev->dev_private = private;
 
 	INIT_LIST_HEAD(&private->psr_list);
-	mutex_init(&private->psr_list_mutex);
+	spin_lock_init(&private->psr_list_lock);
 
 	drm_mode_config_init(drm_dev);
 
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
index 6281ac6..653aeb8 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
@@ -75,7 +75,7 @@ struct rockchip_drm_private {
 	struct drm_mm mm;
 
 	struct list_head psr_list;
-	struct mutex psr_list_mutex;
+	spinlock_t psr_list_lock;
 };
 
 void rockchip_drm_atomic_work(struct work_struct *work);
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
index 04d1c71..6a51851 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
@@ -41,17 +41,18 @@ static struct psr_drv *find_psr_by_crtc(struct drm_crtc *crtc)
 {
 	struct rockchip_drm_private *drm_drv = crtc->dev->dev_private;
 	struct psr_drv *psr;
+	unsigned long flags;
 
-	mutex_lock(&drm_drv->psr_list_mutex);
+	spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
 	list_for_each_entry(psr, &drm_drv->psr_list, list) {
-		if (psr->encoder->crtc == crtc) {
-			mutex_unlock(&drm_drv->psr_list_mutex);
-			return psr;
-		}
+		if (psr->encoder->crtc == crtc)
+			goto out;
 	}
-	mutex_unlock(&drm_drv->psr_list_mutex);
+	psr = ERR_PTR(-ENODEV);
 
-	return ERR_PTR(-ENODEV);
+out:
+	spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
+	return psr;
 }
 
 static void psr_set_state(struct psr_drv *psr, enum psr_state state)
@@ -142,8 +143,9 @@ void rockchip_drm_psr_flush(struct drm_device *dev)
 {
 	struct rockchip_drm_private *drm_drv = dev->dev_private;
 	struct psr_drv *psr;
+	unsigned long flags;
 
-	mutex_lock(&drm_drv->psr_list_mutex);
+	spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
 	list_for_each_entry(psr, &drm_drv->psr_list, list) {
 		if (psr->state == PSR_DISABLE)
 			continue;
@@ -153,7 +155,7 @@ void rockchip_drm_psr_flush(struct drm_device *dev)
 
 		psr_set_state(psr, PSR_FLUSH);
 	}
-	mutex_unlock(&drm_drv->psr_list_mutex);
+	spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
 }
 EXPORT_SYMBOL(rockchip_drm_psr_flush);
 
@@ -170,6 +172,7 @@ int rockchip_drm_psr_register(struct drm_encoder *encoder,
 {
 	struct rockchip_drm_private *drm_drv = encoder->dev->dev_private;
 	struct psr_drv *psr;
+	unsigned long flags;
 
 	if (!encoder || !psr_set)
 		return -EINVAL;
@@ -186,9 +189,9 @@ int rockchip_drm_psr_register(struct drm_encoder *encoder,
 	psr->encoder = encoder;
 	psr->set = psr_set;
 
-	mutex_lock(&drm_drv->psr_list_mutex);
+	spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
 	list_add_tail(&psr->list, &drm_drv->psr_list);
-	mutex_unlock(&drm_drv->psr_list_mutex);
+	spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
 
 	return 0;
 }
@@ -206,8 +209,9 @@ void rockchip_drm_psr_unregister(struct drm_encoder *encoder)
 {
 	struct rockchip_drm_private *drm_drv = encoder->dev->dev_private;
 	struct psr_drv *psr, *n;
+	unsigned long flags;
 
-	mutex_lock(&drm_drv->psr_list_mutex);
+	spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
 	list_for_each_entry_safe(psr, n, &drm_drv->psr_list, list) {
 		if (psr->encoder == encoder) {
 			del_timer(&psr->flush_timer);
@@ -215,6 +219,6 @@ void rockchip_drm_psr_unregister(struct drm_encoder *encoder)
 			kfree(psr);
 		}
 	}
-	mutex_unlock(&drm_drv->psr_list_mutex);
+	spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
 }
 EXPORT_SYMBOL(rockchip_drm_psr_unregister);
-- 
2.8.0.rc3.226.g39d4020