drm/i915: add the FBC mutex

Make sure we're not going to have weird races in really weird cases
where a lot of different CRTCs are doing rendering and modesets at the
same time.

With this change and the stolen_lock from the previous patch, we can
start removing the struct_mutex locking we have around FBC in the next
patches.

v2:
 - Rebase (6 months later)
 - Also lock debugfs and stolen.
v3:
 - Don't lock a single value read (Chris).
 - Replace lockdep assertions with WARNs (Daniel).
 - Improve commit message.
 - Don't forget intel_pre_plane_update() locking.
v4:
 - Don't remove struct_mutex at intel_pre_plane_update() (Chris).
 - Add comment regarding locking dependencies (Chris).
 - Rebase after the stolen code rework.
 - Rebase again after drm-intel-nightly changes.
v5:
 - Rebase after the new stolen_lock patch.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v4)
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 6a8de04c6a2bb9642320edd1b23a83ae06f2ab16..cc74a92dd346554a602f1d6db52e5229f269f909 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1633,6 +1633,7 @@ static int i915_fbc_status(struct seq_file *m, void *unused)
        }
 
        intel_runtime_pm_get(dev_priv);
+       mutex_lock(&dev_priv->fbc.lock);
 
        if (intel_fbc_enabled(dev))
                seq_puts(m, "FBC enabled\n");
@@ -1645,6 +1646,7 @@ static int i915_fbc_status(struct seq_file *m, void *unused)
                           yesno(I915_READ(FBC_STATUS2) &
                                 FBC_COMPRESSION_MASK));
 
+       mutex_unlock(&dev_priv->fbc.lock);
        intel_runtime_pm_put(dev_priv);
 
        return 0;
@@ -1675,6 +1677,7 @@ static int i915_fbc_fc_set(void *data, u64 val)
                return -ENODEV;
 
        drm_modeset_lock_all(dev);
+       mutex_lock(&dev_priv->fbc.lock);
 
        reg = I915_READ(ILK_DPFC_CONTROL);
        dev_priv->fbc.false_color = val;
@@ -1683,6 +1686,7 @@ static int i915_fbc_fc_set(void *data, u64 val)
                   (reg | FBC_CTL_FALSE_COLOR) :
                   (reg & ~FBC_CTL_FALSE_COLOR));
 
+       mutex_unlock(&dev_priv->fbc.lock);
        drm_modeset_unlock_all(dev);
        return 0;
 }

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index eb10c16240067ce273bfb5ef829b067093d5f1a2..093d6421dddfa4b54014ba8d778f2a40e83e3341 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -899,6 +899,9 @@ enum fb_op_origin {
 };
 
 struct i915_fbc {
+       /* This is always the inner lock when overlapping with struct_mutex and
+        * it's the outer lock when overlapping with stolen_lock. */
+       struct mutex lock;
        unsigned long uncompressed_size;
        unsigned threshold;
        unsigned int fb_id;

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 136b533718786c258e46d4b980730752e99c7afd..93d3bdf242a94c9678c0152df83fc3d8661f1fe4 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4783,11 +4783,9 @@ static void intel_pre_plane_update(struct intel_crtc *crtc)
        if (atomic->wait_for_flips)
                intel_crtc_wait_for_pending_flips(&crtc->base);
 
-       if (atomic->disable_fbc &&
-           dev_priv->fbc.crtc == crtc) {
+       if (atomic->disable_fbc) {
                mutex_lock(&dev->struct_mutex);
-               if (dev_priv->fbc.crtc == crtc)
-                       intel_fbc_disable(dev);
+               intel_fbc_disable_crtc(crtc);
                mutex_unlock(&dev->struct_mutex);
        }
 

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 82abbfae4e23e19009ccdd1a4b81da67a28b54e8..63d7d32e61230d803ddca1ae2289610a111645a4 100644 (file)
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1252,6 +1252,7 @@ bool intel_fbc_enabled(struct drm_device *dev);
 void intel_fbc_update(struct drm_device *dev);
 void intel_fbc_init(struct drm_i915_private *dev_priv);
 void intel_fbc_disable(struct drm_device *dev);
+void intel_fbc_disable_crtc(struct intel_crtc *crtc);
 void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
                          unsigned int frontbuffer_bits,
                          enum fb_op_origin origin);

diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 55711b452fbf809d12be7595ae50f9bdb8c35ae3..a076c7a25062fde517071581d730c4b4a7a7e875 100644 (file)
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -336,6 +336,7 @@ static void intel_fbc_work_fn(struct work_struct *__work)
        struct drm_i915_private *dev_priv = dev->dev_private;
 
        mutex_lock(&dev->struct_mutex);
+       mutex_lock(&dev_priv->fbc.lock);
        if (work == dev_priv->fbc.fbc_work) {
                /* Double check that we haven't switched fb without cancelling
                 * the prior work.
@@ -350,6 +351,7 @@ static void intel_fbc_work_fn(struct work_struct *__work)
 
                dev_priv->fbc.fbc_work = NULL;
        }
+       mutex_unlock(&dev_priv->fbc.lock);
        mutex_unlock(&dev->struct_mutex);
 
        kfree(work);
@@ -357,6 +359,8 @@ static void intel_fbc_work_fn(struct work_struct *__work)
 
 static void intel_fbc_cancel_work(struct drm_i915_private *dev_priv)
 {
+       WARN_ON(!mutex_is_locked(&dev_priv->fbc.lock));
+
        if (dev_priv->fbc.fbc_work == NULL)
                return;
 
@@ -384,6 +388,8 @@ static void intel_fbc_enable(struct drm_crtc *crtc)
        struct drm_device *dev = crtc->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
 
+       WARN_ON(!mutex_is_locked(&dev_priv->fbc.lock));
+
        if (!dev_priv->display.enable_fbc)
                return;
 
@@ -418,6 +424,21 @@ static void intel_fbc_enable(struct drm_crtc *crtc)
        schedule_delayed_work(&work->work, msecs_to_jiffies(50));
 }
 
+static void __intel_fbc_disable(struct drm_device *dev)
+{
+       struct drm_i915_private *dev_priv = dev->dev_private;
+
+       WARN_ON(!mutex_is_locked(&dev_priv->fbc.lock));
+
+       intel_fbc_cancel_work(dev_priv);
+
+       if (!dev_priv->display.disable_fbc)
+               return;
+
+       dev_priv->display.disable_fbc(dev);
+       dev_priv->fbc.crtc = NULL;
+}
+
 /**
  * intel_fbc_disable - disable FBC
  * @dev: the drm_device
@@ -428,13 +449,26 @@ void intel_fbc_disable(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
 
-       intel_fbc_cancel_work(dev_priv);
+       mutex_lock(&dev_priv->fbc.lock);
+       __intel_fbc_disable(dev);
+       mutex_unlock(&dev_priv->fbc.lock);
+}
 
-       if (!dev_priv->display.disable_fbc)
-               return;
+/*
+ * intel_fbc_disable_crtc - disable FBC if it's associated with crtc
+ * @crtc: the CRTC
+ *
+ * This function disables FBC if it's associated with the provided CRTC.
+ */
+void intel_fbc_disable_crtc(struct intel_crtc *crtc)
+{
+       struct drm_device *dev = crtc->base.dev;
+       struct drm_i915_private *dev_priv = dev->dev_private;
 
-       dev_priv->display.disable_fbc(dev);
-       dev_priv->fbc.crtc = NULL;
+       mutex_lock(&dev_priv->fbc.lock);
+       if (dev_priv->fbc.crtc == crtc)
+               __intel_fbc_disable(dev);
+       mutex_unlock(&dev_priv->fbc.lock);
 }
 
 const char *intel_no_fbc_reason_str(enum no_fbc_reason reason)
@@ -607,7 +641,7 @@ err_llb:
        return -ENOSPC;
 }
 
-void intel_fbc_cleanup_cfb(struct drm_device *dev)
+static void __intel_fbc_cleanup_cfb(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
 
@@ -625,6 +659,15 @@ void intel_fbc_cleanup_cfb(struct drm_device *dev)
        dev_priv->fbc.uncompressed_size = 0;
 }
 
+void intel_fbc_cleanup_cfb(struct drm_device *dev)
+{
+       struct drm_i915_private *dev_priv = dev->dev_private;
+
+       mutex_lock(&dev_priv->fbc.lock);
+       __intel_fbc_cleanup_cfb(dev);
+       mutex_unlock(&dev_priv->fbc.lock);
+}
+
 static int intel_fbc_setup_cfb(struct drm_device *dev, int size, int fb_cpp)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
@@ -633,13 +676,13 @@ static int intel_fbc_setup_cfb(struct drm_device *dev, int size, int fb_cpp)
                return 0;
 
        /* Release any current block */
-       intel_fbc_cleanup_cfb(dev);
+       __intel_fbc_cleanup_cfb(dev);
 
        return intel_fbc_alloc_cfb(dev, size, fb_cpp);
 }
 
 /**
- * intel_fbc_update - enable/disable FBC as needed
+ * __intel_fbc_update - enable/disable FBC as needed, unlocked
  * @dev: the drm_device
  *
  * Set up the framebuffer compression hardware at mode set time.  We
@@ -657,7 +700,7 @@ static int intel_fbc_setup_cfb(struct drm_device *dev, int size, int fb_cpp)
  *
  * We need to enable/disable FBC on a global basis.
  */
-void intel_fbc_update(struct drm_device *dev)
+static void __intel_fbc_update(struct drm_device *dev)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_crtc *crtc = NULL;
@@ -670,6 +713,8 @@ void intel_fbc_update(struct drm_device *dev)
        if (!HAS_FBC(dev))
                return;
 
+       WARN_ON(!mutex_is_locked(&dev_priv->fbc.lock));
+
        /* disable framebuffer compression in vGPU */
        if (intel_vgpu_active(dev))
                i915.enable_fbc = 0;
@@ -788,7 +833,7 @@ void intel_fbc_update(struct drm_device *dev)
                 * some point. And we wait before enabling FBC anyway.
                 */
                DRM_DEBUG_KMS("disabling active FBC for update\n");
-               intel_fbc_disable(dev);
+               __intel_fbc_disable(dev);
        }
 
        intel_fbc_enable(crtc);
@@ -799,9 +844,24 @@ out_disable:
        /* Multiple disables should be harmless */
        if (intel_fbc_enabled(dev)) {
                DRM_DEBUG_KMS("unsupported config, disabling FBC\n");
-               intel_fbc_disable(dev);
+               __intel_fbc_disable(dev);
        }
-       intel_fbc_cleanup_cfb(dev);
+       __intel_fbc_cleanup_cfb(dev);
+}
+
+/*
+ * intel_fbc_update - enable/disable FBC as needed
+ * @dev: the drm_device
+ *
+ * This function reevaluates the overall state and enables or disables FBC.
+ */
+void intel_fbc_update(struct drm_device *dev)
+{
+       struct drm_i915_private *dev_priv = dev->dev_private;
+
+       mutex_lock(&dev_priv->fbc.lock);
+       __intel_fbc_update(dev);
+       mutex_unlock(&dev_priv->fbc.lock);
 }
 
 void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
@@ -814,6 +874,8 @@ void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
        if (origin == ORIGIN_GTT)
                return;
 
+       mutex_lock(&dev_priv->fbc.lock);
+
        if (dev_priv->fbc.enabled)
                fbc_bits = INTEL_FRONTBUFFER_PRIMARY(dev_priv->fbc.crtc->pipe);
        else if (dev_priv->fbc.fbc_work)
@@ -825,7 +887,9 @@ void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
        dev_priv->fbc.busy_bits |= (fbc_bits & frontbuffer_bits);
 
        if (dev_priv->fbc.busy_bits)
-               intel_fbc_disable(dev);
+               __intel_fbc_disable(dev);
+
+       mutex_unlock(&dev_priv->fbc.lock);
 }
 
 void intel_fbc_flush(struct drm_i915_private *dev_priv,
@@ -833,13 +897,18 @@ void intel_fbc_flush(struct drm_i915_private *dev_priv,
 {
        struct drm_device *dev = dev_priv->dev;
 
+       mutex_lock(&dev_priv->fbc.lock);
+
        if (!dev_priv->fbc.busy_bits)
-               return;
+               goto out;
 
        dev_priv->fbc.busy_bits &= ~frontbuffer_bits;
 
        if (!dev_priv->fbc.busy_bits)
-               intel_fbc_update(dev);
+               __intel_fbc_update(dev);
+
+out:
+       mutex_unlock(&dev_priv->fbc.lock);
 }
 
 /**
@@ -852,6 +921,8 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
 {
        enum pipe pipe;
 
+       mutex_init(&dev_priv->fbc.lock);
+
        if (!HAS_FBC(dev_priv)) {
                dev_priv->fbc.enabled = false;
                dev_priv->fbc.no_fbc_reason = FBC_UNSUPPORTED;