drm/tilcdc: Fix race from forced shutdown of crtc in unload

Fix race from forced shutdown of crtc in unload by adding internal
locking and a boolean telling if device is going to be shutdown.

Signed-off-by: Jyri Sarha <jsarha@ti.com>

3 files changed, 26 insertions, 8 deletions

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 62773633ef5a..0d09acce4916 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -33,7 +33,9 @@ struct tilcdc_crtc {
         struct drm_plane primary;
         const struct tilcdc_panel_info *info;
         struct drm_pending_vblank_event *event;
+        struct mutex enable_lock;
         bool enabled;
+        bool shutdown;
         wait_queue_head_t frame_done_wq;
         bool frame_done;
         spinlock_t irq_lock;
@@ -158,9 +160,11 @@ static void tilcdc_crtc_enable(struct drm_crtc *crtc)
         struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
 
         WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
-
-        if (tilcdc_crtc->enabled)
+        mutex_lock(&tilcdc_crtc->enable_lock);
+        if (tilcdc_crtc->enabled || tilcdc_crtc->shutdown) {
+                mutex_unlock(&tilcdc_crtc->enable_lock);
                 return;
+        }
 
         pm_runtime_get_sync(dev->dev);
 
@@ -175,17 +179,22 @@ static void tilcdc_crtc_enable(struct drm_crtc *crtc)
         drm_crtc_vblank_on(crtc);
 
         tilcdc_crtc->enabled = true;
+        mutex_unlock(&tilcdc_crtc->enable_lock);
 }
 
-void tilcdc_crtc_off(struct drm_crtc *crtc)
+static void tilcdc_crtc_off(struct drm_crtc *crtc, bool shutdown)
 {
         struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
         struct drm_device *dev = crtc->dev;
         struct tilcdc_drm_private *priv = dev->dev_private;
 
-        if (!tilcdc_crtc->enabled)
+        mutex_lock(&tilcdc_crtc->enable_lock);
+        if (shutdown)
+                tilcdc_crtc->shutdown = true;
+        if (!tilcdc_crtc->enabled) {
+                mutex_unlock(&tilcdc_crtc->enable_lock);
                 return;
-
+        }
         tilcdc_crtc->frame_done = false;
         tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
 
@@ -224,12 +233,18 @@ void tilcdc_crtc_off(struct drm_crtc *crtc)
         tilcdc_crtc->last_vblank = ktime_set(0, 0);
 
         tilcdc_crtc->enabled = false;
+        mutex_unlock(&tilcdc_crtc->enable_lock);
 }
 
 static void tilcdc_crtc_disable(struct drm_crtc *crtc)
 {
         WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
-        tilcdc_crtc_off(crtc);
+        tilcdc_crtc_off(crtc, false);
+}
+
+void tilcdc_crtc_shutdown(struct drm_crtc *crtc)
+{
+        tilcdc_crtc_off(crtc, true);
 }
 
 static bool tilcdc_crtc_is_on(struct drm_crtc *crtc)
@@ -857,6 +872,8 @@ struct drm_crtc *tilcdc_crtc_create(struct drm_device *dev)
         if (ret < 0)
                 goto fail;
 
+        mutex_init(&tilcdc_crtc->enable_lock);
+
         init_waitqueue_head(&tilcdc_crtc->frame_done_wq);
 
         drm_flip_work_init(&tilcdc_crtc->unref_work,
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
index 48757f1a1a59..3d2cea090d6f 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
@@ -197,7 +197,7 @@ static void tilcdc_fini(struct drm_device *dev)
         struct tilcdc_drm_private *priv = dev->dev_private;
 
         if (priv->crtc)
-                tilcdc_crtc_off(priv->crtc);
+                tilcdc_crtc_shutdown(priv->crtc);
 
         if (priv->is_registered)
                 drm_dev_unregister(dev);
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.h b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
index 7db23f27e9fb..d31fe5d8ab9d 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.h
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
@@ -33,6 +33,7 @@
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_bridge.h>
 
 /* Defaulting to pixel clock defined on AM335x */
 #define TILCDC_DEFAULT_MAX_PIXELCLOCK  126000
@@ -173,7 +174,7 @@ void tilcdc_crtc_set_simulate_vesa_sync(struct drm_crtc *crtc,
                                         bool simulate_vesa_sync);
 int tilcdc_crtc_mode_valid(struct drm_crtc *crtc, struct drm_display_mode *mode);
 int tilcdc_crtc_max_width(struct drm_crtc *crtc);
-void tilcdc_crtc_off(struct drm_crtc *crtc);
+void tilcdc_crtc_shutdown(struct drm_crtc *crtc);
 int tilcdc_crtc_update_fb(struct drm_crtc *crtc,
                 struct drm_framebuffer *fb,
                 struct drm_pending_vblank_event *event);