[PATCHv3 4/4] drm/tilcdc: Fix race from forced shutdown of crtc in unload

[Jyri Sarha]

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 at ti.com>
---
 drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 29 +++++++++++++++++++++++------
 drivers/gpu/drm/tilcdc/tilcdc_drv.c  |  2 +-
 drivers/gpu/drm/tilcdc/tilcdc_drv.h  |  3 ++-
 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 6277363..0d09acc 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 14896b6..dcc9621 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 7db23f2..d31fe5d 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);
-- 
1.9.1