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path: root/drivers/gpu/drm/vmwgfx
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Diffstat (limited to 'drivers/gpu/drm/vmwgfx')
-rw-r--r--drivers/gpu/drm/vmwgfx/vmwgfx_drv.c28
-rw-r--r--drivers/gpu/drm/vmwgfx/vmwgfx_drv.h25
-rw-r--r--drivers/gpu/drm/vmwgfx/vmwgfx_fence.c18
-rw-r--r--drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c36
-rw-r--r--drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c8
-rw-r--r--drivers/gpu/drm/vmwgfx/vmwgfx_irq.c25
-rw-r--r--drivers/gpu/drm/vmwgfx/vmwgfx_kms.c2
7 files changed, 56 insertions, 86 deletions
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index 7b5d22110f25..6c6b655defcf 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -406,11 +406,9 @@ int vmw_3d_resource_inc(struct vmw_private *dev_priv,
if (unlikely(ret != 0))
--dev_priv->num_3d_resources;
} else if (unhide_svga) {
- mutex_lock(&dev_priv->hw_mutex);
vmw_write(dev_priv, SVGA_REG_ENABLE,
vmw_read(dev_priv, SVGA_REG_ENABLE) &
~SVGA_REG_ENABLE_HIDE);
- mutex_unlock(&dev_priv->hw_mutex);
}
mutex_unlock(&dev_priv->release_mutex);
@@ -433,13 +431,10 @@ void vmw_3d_resource_dec(struct vmw_private *dev_priv,
mutex_lock(&dev_priv->release_mutex);
if (unlikely(--dev_priv->num_3d_resources == 0))
vmw_release_device(dev_priv);
- else if (hide_svga) {
- mutex_lock(&dev_priv->hw_mutex);
+ else if (hide_svga)
vmw_write(dev_priv, SVGA_REG_ENABLE,
vmw_read(dev_priv, SVGA_REG_ENABLE) |
SVGA_REG_ENABLE_HIDE);
- mutex_unlock(&dev_priv->hw_mutex);
- }
n3d = (int32_t) dev_priv->num_3d_resources;
mutex_unlock(&dev_priv->release_mutex);
@@ -600,12 +595,14 @@ static int vmw_driver_load(struct drm_device *dev, unsigned long chipset)
dev_priv->dev = dev;
dev_priv->vmw_chipset = chipset;
dev_priv->last_read_seqno = (uint32_t) -100;
- mutex_init(&dev_priv->hw_mutex);
mutex_init(&dev_priv->cmdbuf_mutex);
mutex_init(&dev_priv->release_mutex);
mutex_init(&dev_priv->binding_mutex);
rwlock_init(&dev_priv->resource_lock);
ttm_lock_init(&dev_priv->reservation_sem);
+ spin_lock_init(&dev_priv->hw_lock);
+ spin_lock_init(&dev_priv->waiter_lock);
+ spin_lock_init(&dev_priv->cap_lock);
for (i = vmw_res_context; i < vmw_res_max; ++i) {
idr_init(&dev_priv->res_idr[i]);
@@ -626,14 +623,11 @@ static int vmw_driver_load(struct drm_device *dev, unsigned long chipset)
dev_priv->enable_fb = enable_fbdev;
- mutex_lock(&dev_priv->hw_mutex);
-
vmw_write(dev_priv, SVGA_REG_ID, SVGA_ID_2);
svga_id = vmw_read(dev_priv, SVGA_REG_ID);
if (svga_id != SVGA_ID_2) {
ret = -ENOSYS;
DRM_ERROR("Unsupported SVGA ID 0x%x\n", svga_id);
- mutex_unlock(&dev_priv->hw_mutex);
goto out_err0;
}
@@ -683,10 +677,8 @@ static int vmw_driver_load(struct drm_device *dev, unsigned long chipset)
dev_priv->prim_bb_mem = dev_priv->vram_size;
ret = vmw_dma_masks(dev_priv);
- if (unlikely(ret != 0)) {
- mutex_unlock(&dev_priv->hw_mutex);
+ if (unlikely(ret != 0))
goto out_err0;
- }
/*
* Limit back buffer size to VRAM size. Remove this once
@@ -695,8 +687,6 @@ static int vmw_driver_load(struct drm_device *dev, unsigned long chipset)
if (dev_priv->prim_bb_mem > dev_priv->vram_size)
dev_priv->prim_bb_mem = dev_priv->vram_size;
- mutex_unlock(&dev_priv->hw_mutex);
-
vmw_print_capabilities(dev_priv->capabilities);
if (dev_priv->capabilities & SVGA_CAP_GMR2) {
@@ -1160,9 +1150,7 @@ static int vmw_master_set(struct drm_device *dev,
if (unlikely(ret != 0))
return ret;
vmw_kms_save_vga(dev_priv);
- mutex_lock(&dev_priv->hw_mutex);
vmw_write(dev_priv, SVGA_REG_TRACES, 0);
- mutex_unlock(&dev_priv->hw_mutex);
}
if (active) {
@@ -1196,9 +1184,7 @@ out_no_active_lock:
if (!dev_priv->enable_fb) {
vmw_kms_restore_vga(dev_priv);
vmw_3d_resource_dec(dev_priv, true);
- mutex_lock(&dev_priv->hw_mutex);
vmw_write(dev_priv, SVGA_REG_TRACES, 1);
- mutex_unlock(&dev_priv->hw_mutex);
}
return ret;
}
@@ -1233,9 +1219,7 @@ static void vmw_master_drop(struct drm_device *dev,
DRM_ERROR("Unable to clean VRAM on master drop.\n");
vmw_kms_restore_vga(dev_priv);
vmw_3d_resource_dec(dev_priv, true);
- mutex_lock(&dev_priv->hw_mutex);
vmw_write(dev_priv, SVGA_REG_TRACES, 1);
- mutex_unlock(&dev_priv->hw_mutex);
}
dev_priv->active_master = &dev_priv->fbdev_master;
@@ -1367,10 +1351,8 @@ static void vmw_pm_complete(struct device *kdev)
struct drm_device *dev = pci_get_drvdata(pdev);
struct vmw_private *dev_priv = vmw_priv(dev);
- mutex_lock(&dev_priv->hw_mutex);
vmw_write(dev_priv, SVGA_REG_ID, SVGA_ID_2);
(void) vmw_read(dev_priv, SVGA_REG_ID);
- mutex_unlock(&dev_priv->hw_mutex);
/**
* Reclaim 3d reference held by fbdev and potentially
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index 4ee799b43d5d..d26a6daa9719 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -399,7 +399,8 @@ struct vmw_private {
uint32_t memory_size;
bool has_gmr;
bool has_mob;
- struct mutex hw_mutex;
+ spinlock_t hw_lock;
+ spinlock_t cap_lock;
/*
* VGA registers.
@@ -449,8 +450,9 @@ struct vmw_private {
atomic_t marker_seq;
wait_queue_head_t fence_queue;
wait_queue_head_t fifo_queue;
- int fence_queue_waiters; /* Protected by hw_mutex */
- int goal_queue_waiters; /* Protected by hw_mutex */
+ spinlock_t waiter_lock;
+ int fence_queue_waiters; /* Protected by waiter_lock */
+ int goal_queue_waiters; /* Protected by waiter_lock */
atomic_t fifo_queue_waiters;
uint32_t last_read_seqno;
spinlock_t irq_lock;
@@ -553,20 +555,35 @@ static inline struct vmw_master *vmw_master(struct drm_master *master)
return (struct vmw_master *) master->driver_priv;
}
+/*
+ * The locking here is fine-grained, so that it is performed once
+ * for every read- and write operation. This is of course costly, but we
+ * don't perform much register access in the timing critical paths anyway.
+ * Instead we have the extra benefit of being sure that we don't forget
+ * the hw lock around register accesses.
+ */
static inline void vmw_write(struct vmw_private *dev_priv,
unsigned int offset, uint32_t value)
{
+ unsigned long irq_flags;
+
+ spin_lock_irqsave(&dev_priv->hw_lock, irq_flags);
outl(offset, dev_priv->io_start + VMWGFX_INDEX_PORT);
outl(value, dev_priv->io_start + VMWGFX_VALUE_PORT);
+ spin_unlock_irqrestore(&dev_priv->hw_lock, irq_flags);
}
static inline uint32_t vmw_read(struct vmw_private *dev_priv,
unsigned int offset)
{
- uint32_t val;
+ unsigned long irq_flags;
+ u32 val;
+ spin_lock_irqsave(&dev_priv->hw_lock, irq_flags);
outl(offset, dev_priv->io_start + VMWGFX_INDEX_PORT);
val = inl(dev_priv->io_start + VMWGFX_VALUE_PORT);
+ spin_unlock_irqrestore(&dev_priv->hw_lock, irq_flags);
+
return val;
}
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
index b7594cb758af..945f1e0dad92 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
@@ -35,7 +35,7 @@ struct vmw_fence_manager {
struct vmw_private *dev_priv;
spinlock_t lock;
struct list_head fence_list;
- struct work_struct work, ping_work;
+ struct work_struct work;
u32 user_fence_size;
u32 fence_size;
u32 event_fence_action_size;
@@ -134,14 +134,6 @@ static const char *vmw_fence_get_timeline_name(struct fence *f)
return "svga";
}
-static void vmw_fence_ping_func(struct work_struct *work)
-{
- struct vmw_fence_manager *fman =
- container_of(work, struct vmw_fence_manager, ping_work);
-
- vmw_fifo_ping_host(fman->dev_priv, SVGA_SYNC_GENERIC);
-}
-
static bool vmw_fence_enable_signaling(struct fence *f)
{
struct vmw_fence_obj *fence =
@@ -155,11 +147,7 @@ static bool vmw_fence_enable_signaling(struct fence *f)
if (seqno - fence->base.seqno < VMW_FENCE_WRAP)
return false;
- if (mutex_trylock(&dev_priv->hw_mutex)) {
- vmw_fifo_ping_host_locked(dev_priv, SVGA_SYNC_GENERIC);
- mutex_unlock(&dev_priv->hw_mutex);
- } else
- schedule_work(&fman->ping_work);
+ vmw_fifo_ping_host(dev_priv, SVGA_SYNC_GENERIC);
return true;
}
@@ -305,7 +293,6 @@ struct vmw_fence_manager *vmw_fence_manager_init(struct vmw_private *dev_priv)
INIT_LIST_HEAD(&fman->fence_list);
INIT_LIST_HEAD(&fman->cleanup_list);
INIT_WORK(&fman->work, &vmw_fence_work_func);
- INIT_WORK(&fman->ping_work, &vmw_fence_ping_func);
fman->fifo_down = true;
fman->user_fence_size = ttm_round_pot(sizeof(struct vmw_user_fence));
fman->fence_size = ttm_round_pot(sizeof(struct vmw_fence_obj));
@@ -323,7 +310,6 @@ void vmw_fence_manager_takedown(struct vmw_fence_manager *fman)
bool lists_empty;
(void) cancel_work_sync(&fman->work);
- (void) cancel_work_sync(&fman->ping_work);
spin_lock_irqsave(&fman->lock, irq_flags);
lists_empty = list_empty(&fman->fence_list) &&
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
index 09e10aefcd8e..39f2b03888e7 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
@@ -44,10 +44,10 @@ bool vmw_fifo_have_3d(struct vmw_private *dev_priv)
if (!dev_priv->has_mob)
return false;
- mutex_lock(&dev_priv->hw_mutex);
+ spin_lock(&dev_priv->cap_lock);
vmw_write(dev_priv, SVGA_REG_DEV_CAP, SVGA3D_DEVCAP_3D);
result = vmw_read(dev_priv, SVGA_REG_DEV_CAP);
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock(&dev_priv->cap_lock);
return (result != 0);
}
@@ -120,7 +120,6 @@ int vmw_fifo_init(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
DRM_INFO("height %d\n", vmw_read(dev_priv, SVGA_REG_HEIGHT));
DRM_INFO("bpp %d\n", vmw_read(dev_priv, SVGA_REG_BITS_PER_PIXEL));
- mutex_lock(&dev_priv->hw_mutex);
dev_priv->enable_state = vmw_read(dev_priv, SVGA_REG_ENABLE);
dev_priv->config_done_state = vmw_read(dev_priv, SVGA_REG_CONFIG_DONE);
dev_priv->traces_state = vmw_read(dev_priv, SVGA_REG_TRACES);
@@ -143,7 +142,6 @@ int vmw_fifo_init(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
mb();
vmw_write(dev_priv, SVGA_REG_CONFIG_DONE, 1);
- mutex_unlock(&dev_priv->hw_mutex);
max = ioread32(fifo_mem + SVGA_FIFO_MAX);
min = ioread32(fifo_mem + SVGA_FIFO_MIN);
@@ -160,31 +158,28 @@ int vmw_fifo_init(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
return vmw_fifo_send_fence(dev_priv, &dummy);
}
-void vmw_fifo_ping_host_locked(struct vmw_private *dev_priv, uint32_t reason)
+void vmw_fifo_ping_host(struct vmw_private *dev_priv, uint32_t reason)
{
__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
+ static DEFINE_SPINLOCK(ping_lock);
+ unsigned long irq_flags;
+ /*
+ * The ping_lock is needed because we don't have an atomic
+ * test-and-set of the SVGA_FIFO_BUSY register.
+ */
+ spin_lock_irqsave(&ping_lock, irq_flags);
if (unlikely(ioread32(fifo_mem + SVGA_FIFO_BUSY) == 0)) {
iowrite32(1, fifo_mem + SVGA_FIFO_BUSY);
vmw_write(dev_priv, SVGA_REG_SYNC, reason);
}
-}
-
-void vmw_fifo_ping_host(struct vmw_private *dev_priv, uint32_t reason)
-{
- mutex_lock(&dev_priv->hw_mutex);
-
- vmw_fifo_ping_host_locked(dev_priv, reason);
-
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock_irqrestore(&ping_lock, irq_flags);
}
void vmw_fifo_release(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
{
__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
- mutex_lock(&dev_priv->hw_mutex);
-
vmw_write(dev_priv, SVGA_REG_SYNC, SVGA_SYNC_GENERIC);
while (vmw_read(dev_priv, SVGA_REG_BUSY) != 0)
;
@@ -198,7 +193,6 @@ void vmw_fifo_release(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
vmw_write(dev_priv, SVGA_REG_TRACES,
dev_priv->traces_state);
- mutex_unlock(&dev_priv->hw_mutex);
vmw_marker_queue_takedown(&fifo->marker_queue);
if (likely(fifo->static_buffer != NULL)) {
@@ -271,7 +265,7 @@ static int vmw_fifo_wait(struct vmw_private *dev_priv,
return vmw_fifo_wait_noirq(dev_priv, bytes,
interruptible, timeout);
- mutex_lock(&dev_priv->hw_mutex);
+ spin_lock(&dev_priv->waiter_lock);
if (atomic_add_return(1, &dev_priv->fifo_queue_waiters) > 0) {
spin_lock_irqsave(&dev_priv->irq_lock, irq_flags);
outl(SVGA_IRQFLAG_FIFO_PROGRESS,
@@ -280,7 +274,7 @@ static int vmw_fifo_wait(struct vmw_private *dev_priv,
vmw_write(dev_priv, SVGA_REG_IRQMASK, dev_priv->irq_mask);
spin_unlock_irqrestore(&dev_priv->irq_lock, irq_flags);
}
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock(&dev_priv->waiter_lock);
if (interruptible)
ret = wait_event_interruptible_timeout
@@ -296,14 +290,14 @@ static int vmw_fifo_wait(struct vmw_private *dev_priv,
else if (likely(ret > 0))
ret = 0;
- mutex_lock(&dev_priv->hw_mutex);
+ spin_lock(&dev_priv->waiter_lock);
if (atomic_dec_and_test(&dev_priv->fifo_queue_waiters)) {
spin_lock_irqsave(&dev_priv->irq_lock, irq_flags);
dev_priv->irq_mask &= ~SVGA_IRQFLAG_FIFO_PROGRESS;
vmw_write(dev_priv, SVGA_REG_IRQMASK, dev_priv->irq_mask);
spin_unlock_irqrestore(&dev_priv->irq_lock, irq_flags);
}
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock(&dev_priv->waiter_lock);
return ret;
}
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
index 37881ecf5d7a..69c8ce23123c 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
@@ -135,13 +135,13 @@ static int vmw_fill_compat_cap(struct vmw_private *dev_priv, void *bounce,
(pair_offset + max_size * sizeof(SVGA3dCapPair)) / sizeof(u32);
compat_cap->header.type = SVGA3DCAPS_RECORD_DEVCAPS;
- mutex_lock(&dev_priv->hw_mutex);
+ spin_lock(&dev_priv->cap_lock);
for (i = 0; i < max_size; ++i) {
vmw_write(dev_priv, SVGA_REG_DEV_CAP, i);
compat_cap->pairs[i][0] = i;
compat_cap->pairs[i][1] = vmw_read(dev_priv, SVGA_REG_DEV_CAP);
}
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock(&dev_priv->cap_lock);
return 0;
}
@@ -191,12 +191,12 @@ int vmw_get_cap_3d_ioctl(struct drm_device *dev, void *data,
if (num > SVGA3D_DEVCAP_MAX)
num = SVGA3D_DEVCAP_MAX;
- mutex_lock(&dev_priv->hw_mutex);
+ spin_lock(&dev_priv->cap_lock);
for (i = 0; i < num; ++i) {
vmw_write(dev_priv, SVGA_REG_DEV_CAP, i);
*bounce32++ = vmw_read(dev_priv, SVGA_REG_DEV_CAP);
}
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock(&dev_priv->cap_lock);
} else if (gb_objects) {
ret = vmw_fill_compat_cap(dev_priv, bounce, size);
if (unlikely(ret != 0))
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_irq.c b/drivers/gpu/drm/vmwgfx/vmwgfx_irq.c
index 0c423766c441..9fe9827ee499 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_irq.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_irq.c
@@ -62,13 +62,8 @@ irqreturn_t vmw_irq_handler(int irq, void *arg)
static bool vmw_fifo_idle(struct vmw_private *dev_priv, uint32_t seqno)
{
- uint32_t busy;
- mutex_lock(&dev_priv->hw_mutex);
- busy = vmw_read(dev_priv, SVGA_REG_BUSY);
- mutex_unlock(&dev_priv->hw_mutex);
-
- return (busy == 0);
+ return (vmw_read(dev_priv, SVGA_REG_BUSY) == 0);
}
void vmw_update_seqno(struct vmw_private *dev_priv,
@@ -184,7 +179,7 @@ int vmw_fallback_wait(struct vmw_private *dev_priv,
void vmw_seqno_waiter_add(struct vmw_private *dev_priv)
{
- mutex_lock(&dev_priv->hw_mutex);
+ spin_lock(&dev_priv->waiter_lock);
if (dev_priv->fence_queue_waiters++ == 0) {
unsigned long irq_flags;
@@ -195,12 +190,12 @@ void vmw_seqno_waiter_add(struct vmw_private *dev_priv)
vmw_write(dev_priv, SVGA_REG_IRQMASK, dev_priv->irq_mask);
spin_unlock_irqrestore(&dev_priv->irq_lock, irq_flags);
}
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock(&dev_priv->waiter_lock);
}
void vmw_seqno_waiter_remove(struct vmw_private *dev_priv)
{
- mutex_lock(&dev_priv->hw_mutex);
+ spin_lock(&dev_priv->waiter_lock);
if (--dev_priv->fence_queue_waiters == 0) {
unsigned long irq_flags;
@@ -209,13 +204,13 @@ void vmw_seqno_waiter_remove(struct vmw_private *dev_priv)
vmw_write(dev_priv, SVGA_REG_IRQMASK, dev_priv->irq_mask);
spin_unlock_irqrestore(&dev_priv->irq_lock, irq_flags);
}
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock(&dev_priv->waiter_lock);
}
void vmw_goal_waiter_add(struct vmw_private *dev_priv)
{
- mutex_lock(&dev_priv->hw_mutex);
+ spin_lock(&dev_priv->waiter_lock);
if (dev_priv->goal_queue_waiters++ == 0) {
unsigned long irq_flags;
@@ -226,12 +221,12 @@ void vmw_goal_waiter_add(struct vmw_private *dev_priv)
vmw_write(dev_priv, SVGA_REG_IRQMASK, dev_priv->irq_mask);
spin_unlock_irqrestore(&dev_priv->irq_lock, irq_flags);
}
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock(&dev_priv->waiter_lock);
}
void vmw_goal_waiter_remove(struct vmw_private *dev_priv)
{
- mutex_lock(&dev_priv->hw_mutex);
+ spin_lock(&dev_priv->waiter_lock);
if (--dev_priv->goal_queue_waiters == 0) {
unsigned long irq_flags;
@@ -240,7 +235,7 @@ void vmw_goal_waiter_remove(struct vmw_private *dev_priv)
vmw_write(dev_priv, SVGA_REG_IRQMASK, dev_priv->irq_mask);
spin_unlock_irqrestore(&dev_priv->irq_lock, irq_flags);
}
- mutex_unlock(&dev_priv->hw_mutex);
+ spin_unlock(&dev_priv->waiter_lock);
}
int vmw_wait_seqno(struct vmw_private *dev_priv,
@@ -315,9 +310,7 @@ void vmw_irq_uninstall(struct drm_device *dev)
if (!(dev_priv->capabilities & SVGA_CAP_IRQMASK))
return;
- mutex_lock(&dev_priv->hw_mutex);
vmw_write(dev_priv, SVGA_REG_IRQMASK, 0);
- mutex_unlock(&dev_priv->hw_mutex);
status = inl(dev_priv->io_start + VMWGFX_IRQSTATUS_PORT);
outl(status, dev_priv->io_start + VMWGFX_IRQSTATUS_PORT);
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index 3725b521d931..8725b79e7847 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -1828,9 +1828,7 @@ vmw_du_connector_detect(struct drm_connector *connector, bool force)
struct vmw_private *dev_priv = vmw_priv(dev);
struct vmw_display_unit *du = vmw_connector_to_du(connector);
- mutex_lock(&dev_priv->hw_mutex);
num_displays = vmw_read(dev_priv, SVGA_REG_NUM_DISPLAYS);
- mutex_unlock(&dev_priv->hw_mutex);
return ((vmw_connector_to_du(connector)->unit < num_displays &&
du->pref_active) ?