Revert "OMAPFB: simplify locking"

This reverts commit b41deecbda70067b26a3a7704fdf967a7940935b.

The simpler locking causes huge latencies when two processes use the
omapfb, even if they use different framebuffers.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

4 files changed, 132 insertions, 79 deletions

diff --git a/drivers/video/omap2/omapfb/omapfb-ioctl.c b/drivers/video/omap2/omapfb/omapfb-ioctl.c
index dccb158b0d0b..d30b45d72649 100644
--- a/drivers/video/omap2/omapfb/omapfb-ioctl.c
+++ b/drivers/video/omap2/omapfb/omapfb-ioctl.c
@@ -85,6 +85,16 @@ static int omapfb_setup_plane(struct fb_info *fbi, struct omapfb_plane_info *pi)
                 goto out;
         }
 
+        /* Take the locks in a specific order to keep lockdep happy */
+        if (old_rg->id < new_rg->id) {
+                omapfb_get_mem_region(old_rg);
+                omapfb_get_mem_region(new_rg);
+        } else if (new_rg->id < old_rg->id) {
+                omapfb_get_mem_region(new_rg);
+                omapfb_get_mem_region(old_rg);
+        } else
+                omapfb_get_mem_region(old_rg);
+
         if (pi->enabled && !new_rg->size) {
                 /*
                  * This plane's memory was freed, can't enable it
@@ -136,6 +146,16 @@ static int omapfb_setup_plane(struct fb_info *fbi, struct omapfb_plane_info *pi)
                         goto undo;
         }
 
+        /* Release the locks in a specific order to keep lockdep happy */
+        if (old_rg->id > new_rg->id) {
+                omapfb_put_mem_region(old_rg);
+                omapfb_put_mem_region(new_rg);
+        } else if (new_rg->id > old_rg->id) {
+                omapfb_put_mem_region(new_rg);
+                omapfb_put_mem_region(old_rg);
+        } else
+                omapfb_put_mem_region(old_rg);
+
         return 0;
 
  undo:
@@ -146,6 +166,15 @@ static int omapfb_setup_plane(struct fb_info *fbi, struct omapfb_plane_info *pi)
 
         ovl->set_overlay_info(ovl, &old_info);
  put_mem:
+        /* Release the locks in a specific order to keep lockdep happy */
+        if (old_rg->id > new_rg->id) {
+                omapfb_put_mem_region(old_rg);
+                omapfb_put_mem_region(new_rg);
+        } else if (new_rg->id > old_rg->id) {
+                omapfb_put_mem_region(new_rg);
+                omapfb_put_mem_region(old_rg);
+        } else
+                omapfb_put_mem_region(old_rg);
  out:
         dev_err(fbdev->dev, "setup_plane failed\n");
 
@@ -195,10 +224,11 @@ static int omapfb_setup_mem(struct fb_info *fbi, struct omapfb_mem_info *mi)
         if (display && display->driver->sync)
                 display->driver->sync(display);
 
-        mutex_lock(&fbi->mm_lock);
-
         rg = ofbi->region;
 
+        down_write_nested(&rg->lock, rg->id);
+        atomic_inc(&rg->lock_count);
+
         if (rg->size == size && rg->type == mi->type)
                 goto out;
 
@@ -231,7 +261,9 @@ static int omapfb_setup_mem(struct fb_info *fbi, struct omapfb_mem_info *mi)
         }
 
  out:
-        mutex_unlock(&fbi->mm_lock);
+        atomic_dec(&rg->lock_count);
+        up_write(&rg->lock);
+
         return r;
 }
 
@@ -240,12 +272,14 @@ static int omapfb_query_mem(struct fb_info *fbi, struct omapfb_mem_info *mi)
         struct omapfb_info *ofbi = FB2OFB(fbi);
         struct omapfb2_mem_region *rg;
 
-        rg = ofbi->region;
+        rg = omapfb_get_mem_region(ofbi->region);
         memset(mi, 0, sizeof(*mi));
 
         mi->size = rg->size;
         mi->type = rg->type;
 
+        omapfb_put_mem_region(rg);
+
         return 0;
 }
 
@@ -284,10 +318,14 @@ int omapfb_set_update_mode(struct fb_info *fbi,
         if (mode != OMAPFB_AUTO_UPDATE && mode != OMAPFB_MANUAL_UPDATE)
                 return -EINVAL;
 
+        omapfb_lock(fbdev);
+
         d = get_display_data(fbdev, display);
 
-        if (d->update_mode == mode)
+        if (d->update_mode == mode) {
+                omapfb_unlock(fbdev);
                 return 0;
+        }
 
         r = 0;
 
@@ -303,6 +341,8 @@ int omapfb_set_update_mode(struct fb_info *fbi,
                         r = -EINVAL;
         }
 
+        omapfb_unlock(fbdev);
+
         return r;
 }
 
@@ -317,10 +357,14 @@ int omapfb_get_update_mode(struct fb_info *fbi,
         if (!display)
                 return -EINVAL;
 
+        omapfb_lock(fbdev);
+
         d = get_display_data(fbdev, display);
 
         *mode = d->update_mode;
 
+        omapfb_unlock(fbdev);
+
         return 0;
 }
 
@@ -380,10 +424,13 @@ static int omapfb_set_color_key(struct fb_info *fbi,
                 struct omapfb_color_key *ck)
 {
         struct omapfb_info *ofbi = FB2OFB(fbi);
+        struct omapfb2_device *fbdev = ofbi->fbdev;
         int r;
         int i;
         struct omap_overlay_manager *mgr = NULL;
 
+        omapfb_lock(fbdev);
+
         for (i = 0; i < ofbi->num_overlays; i++) {
                 if (ofbi->overlays[i]->manager) {
                         mgr = ofbi->overlays[i]->manager;
@@ -398,6 +445,8 @@ static int omapfb_set_color_key(struct fb_info *fbi,
 
         r = _omapfb_set_color_key(mgr, ck);
 err:
+        omapfb_unlock(fbdev);
+
         return r;
 }
 
@@ -405,10 +454,13 @@ static int omapfb_get_color_key(struct fb_info *fbi,
                 struct omapfb_color_key *ck)
 {
         struct omapfb_info *ofbi = FB2OFB(fbi);
+        struct omapfb2_device *fbdev = ofbi->fbdev;
         struct omap_overlay_manager *mgr = NULL;
         int r = 0;
         int i;
 
+        omapfb_lock(fbdev);
+
         for (i = 0; i < ofbi->num_overlays; i++) {
                 if (ofbi->overlays[i]->manager) {
                         mgr = ofbi->overlays[i]->manager;
@@ -423,6 +475,8 @@ static int omapfb_get_color_key(struct fb_info *fbi,
 
         *ck = omapfb_color_keys[mgr->id];
 err:
+        omapfb_unlock(fbdev);
+
         return r;
 }
 
@@ -549,8 +603,6 @@ int omapfb_ioctl(struct fb_info *fbi, unsigned int cmd, unsigned long arg)
 
         int r = 0;
 
-        omapfb_lock(fbdev);
-
         switch (cmd) {
         case OMAPFB_SYNC_GFX:
                 DBG("ioctl SYNC_GFX\n");
@@ -856,8 +908,6 @@ int omapfb_ioctl(struct fb_info *fbi, unsigned int cmd, unsigned long arg)
                 r = -EINVAL;
         }
 
-        omapfb_unlock(fbdev);
-
         if (r < 0)
                 DBG("ioctl failed: %d\n", r);
 
diff --git a/drivers/video/omap2/omapfb/omapfb-main.c b/drivers/video/omap2/omapfb/omapfb-main.c
index 948dfb9f3e9b..ca585ef37f25 100644
--- a/drivers/video/omap2/omapfb/omapfb-main.c
+++ b/drivers/video/omap2/omapfb/omapfb-main.c
@@ -672,6 +672,8 @@ int check_fb_var(struct fb_info *fbi, struct fb_var_screeninfo *var)
 
         DBG("check_fb_var %d\n", ofbi->id);
 
+        WARN_ON(!atomic_read(&ofbi->region->lock_count));
+
         r = fb_mode_to_dss_mode(var, &mode);
         if (r) {
                 DBG("cannot convert var to omap dss mode\n");
@@ -853,6 +855,8 @@ int omapfb_setup_overlay(struct fb_info *fbi, struct omap_overlay *ovl,
         int rotation = var->rotate;
         int i;
 
+        WARN_ON(!atomic_read(&ofbi->region->lock_count));
+
         for (i = 0; i < ofbi->num_overlays; i++) {
                 if (ovl != ofbi->overlays[i])
                         continue;
@@ -944,6 +948,8 @@ int omapfb_apply_changes(struct fb_info *fbi, int init)
                 fill_fb(fbi);
 #endif
 
+        WARN_ON(!atomic_read(&ofbi->region->lock_count));
+
         for (i = 0; i < ofbi->num_overlays; i++) {
                 ovl = ofbi->overlays[i];
 
@@ -1002,16 +1008,15 @@ err:
 static int omapfb_check_var(struct fb_var_screeninfo *var, struct fb_info *fbi)
 {
         struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
         int r;
 
         DBG("check_var(%d)\n", FB2OFB(fbi)->id);
 
-        omapfb_lock(fbdev);
+        omapfb_get_mem_region(ofbi->region);
 
         r = check_fb_var(fbi, var);
 
-        omapfb_unlock(fbdev);
+        omapfb_put_mem_region(ofbi->region);
 
         return r;
 }
@@ -1020,12 +1025,11 @@ static int omapfb_check_var(struct fb_var_screeninfo *var, struct fb_info *fbi)
 static int omapfb_set_par(struct fb_info *fbi)
 {
         struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
         int r;
 
         DBG("set_par(%d)\n", FB2OFB(fbi)->id);
 
-        omapfb_lock(fbdev);
+        omapfb_get_mem_region(ofbi->region);
 
         set_fb_fix(fbi);
 
@@ -1036,7 +1040,7 @@ static int omapfb_set_par(struct fb_info *fbi)
         r = omapfb_apply_changes(fbi, 0);
 
  out:
-        omapfb_unlock(fbdev);
+        omapfb_put_mem_region(ofbi->region);
 
         return r;
 }
@@ -1045,7 +1049,6 @@ static int omapfb_pan_display(struct fb_var_screeninfo *var,
                 struct fb_info *fbi)
 {
         struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
         struct fb_var_screeninfo new_var;
         int r;
 
@@ -1061,11 +1064,11 @@ static int omapfb_pan_display(struct fb_var_screeninfo *var,
 
         fbi->var = new_var;
 
-        omapfb_lock(fbdev);
+        omapfb_get_mem_region(ofbi->region);
 
         r = omapfb_apply_changes(fbi, 0);
 
-        omapfb_unlock(fbdev);
+        omapfb_put_mem_region(ofbi->region);
 
         return r;
 }
@@ -1074,14 +1077,18 @@ static void mmap_user_open(struct vm_area_struct *vma)
 {
         struct omapfb2_mem_region *rg = vma->vm_private_data;
 
+        omapfb_get_mem_region(rg);
         atomic_inc(&rg->map_count);
+        omapfb_put_mem_region(rg);
 }
 
 static void mmap_user_close(struct vm_area_struct *vma)
 {
         struct omapfb2_mem_region *rg = vma->vm_private_data;
 
+        omapfb_get_mem_region(rg);
         atomic_dec(&rg->map_count);
+        omapfb_put_mem_region(rg);
 }
 
 static struct vm_operations_struct mmap_user_ops = {
@@ -1105,7 +1112,7 @@ static int omapfb_mmap(struct fb_info *fbi, struct vm_area_struct *vma)
                 return -EINVAL;
         off = vma->vm_pgoff << PAGE_SHIFT;
 
-        rg = ofbi->region;
+        rg = omapfb_get_mem_region(ofbi->region);
 
         start = omapfb_get_region_paddr(ofbi);
         len = fix->smem_len;
@@ -1133,9 +1140,13 @@ static int omapfb_mmap(struct fb_info *fbi, struct vm_area_struct *vma)
         /* vm_ops.open won't be called for mmap itself. */
         atomic_inc(&rg->map_count);
 
+        omapfb_put_mem_region(rg);
+
         return 0;
 
  error:
+        omapfb_put_mem_region(ofbi->region);
+
         return r;
 }
 
@@ -1902,6 +1913,7 @@ static int omapfb_create_framebuffers(struct omapfb2_device *fbdev)
 
                 ofbi->region = &fbdev->regions[i];
                 ofbi->region->id = i;
+                init_rwsem(&ofbi->region->lock);
 
                 /* assign these early, so that fb alloc can use them */
                 ofbi->rotation_type = def_vrfb ? OMAP_DSS_ROT_VRFB :
@@ -1933,8 +1945,12 @@ static int omapfb_create_framebuffers(struct omapfb2_device *fbdev)
         /* setup fb_infos */
         for (i = 0; i < fbdev->num_fbs; i++) {
                 struct fb_info *fbi = fbdev->fbs[i];
+                struct omapfb_info *ofbi = FB2OFB(fbi);
 
+                omapfb_get_mem_region(ofbi->region);
                 r = omapfb_fb_init(fbdev, fbi);
+                omapfb_put_mem_region(ofbi->region);
+
                 if (r) {
                         dev_err(fbdev->dev, "failed to setup fb_info\n");
                         return r;
@@ -1966,8 +1982,12 @@ static int omapfb_create_framebuffers(struct omapfb2_device *fbdev)
 
         for (i = 0; i < fbdev->num_fbs; i++) {
                 struct fb_info *fbi = fbdev->fbs[i];
+                struct omapfb_info *ofbi = FB2OFB(fbi);
 
+                omapfb_get_mem_region(ofbi->region);
                 r = omapfb_apply_changes(fbi, 1);
+                omapfb_put_mem_region(ofbi->region);
+
                 if (r) {
                         dev_err(fbdev->dev, "failed to change mode\n");
                         return r;
diff --git a/drivers/video/omap2/omapfb/omapfb-sysfs.c b/drivers/video/omap2/omapfb/omapfb-sysfs.c
index be5eb074b7d3..18fa9e1d0033 100644
--- a/drivers/video/omap2/omapfb/omapfb-sysfs.c
+++ b/drivers/video/omap2/omapfb/omapfb-sysfs.c
@@ -49,7 +49,6 @@ static ssize_t store_rotate_type(struct device *dev,
 {
         struct fb_info *fbi = dev_get_drvdata(dev);
         struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
         struct omapfb2_mem_region *rg;
         int rot_type;
         int r;
@@ -63,13 +62,12 @@ static ssize_t store_rotate_type(struct device *dev,
 
         if (!lock_fb_info(fbi))
                 return -ENODEV;
-        omapfb_lock(fbdev);
 
         r = 0;
         if (rot_type == ofbi->rotation_type)
                 goto out;
 
-        rg = ofbi->region;
+        rg = omapfb_get_mem_region(ofbi->region);
 
         if (rg->size) {
                 r = -EBUSY;
@@ -83,8 +81,8 @@ static ssize_t store_rotate_type(struct device *dev,
          * need to do any further parameter checking at this point.
          */
 put_region:
+        omapfb_put_mem_region(rg);
 out:
-        omapfb_unlock(fbdev);
         unlock_fb_info(fbi);
 
         return r ? r : count;
@@ -106,7 +104,6 @@ static ssize_t store_mirror(struct device *dev,
 {
         struct fb_info *fbi = dev_get_drvdata(dev);
         struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
         bool mirror;
         int r;
         struct fb_var_screeninfo new_var;
@@ -117,10 +114,11 @@ static ssize_t store_mirror(struct device *dev,
 
         if (!lock_fb_info(fbi))
                 return -ENODEV;
-        omapfb_lock(fbdev);
 
         ofbi->mirror = mirror;
 
+        omapfb_get_mem_region(ofbi->region);
+
         memcpy(&new_var, &fbi->var, sizeof(new_var));
         r = check_fb_var(fbi, &new_var);
         if (r)
@@ -135,7 +133,8 @@ static ssize_t store_mirror(struct device *dev,
 
         r = count;
 out:
-        omapfb_unlock(fbdev);
+        omapfb_put_mem_region(ofbi->region);
+
         unlock_fb_info(fbi);
 
         return r;
@@ -274,11 +273,15 @@ static ssize_t store_overlays(struct device *dev, struct device_attribute *attr,
 
                 DBG("detaching %d\n", ofbi->overlays[i]->id);
 
+                omapfb_get_mem_region(ofbi->region);
+
                 omapfb_overlay_enable(ovl, 0);
 
                 if (ovl->manager)
                         ovl->manager->apply(ovl->manager);
 
+                omapfb_put_mem_region(ofbi->region);
+
                 for (t = i + 1; t < ofbi->num_overlays; t++) {
                         ofbi->rotation[t-1] = ofbi->rotation[t];
                         ofbi->overlays[t-1] = ofbi->overlays[t];
@@ -311,8 +314,12 @@ static ssize_t store_overlays(struct device *dev, struct device_attribute *attr,
         }
 
         if (added) {
+                omapfb_get_mem_region(ofbi->region);
+
                 r = omapfb_apply_changes(fbi, 0);
 
+                omapfb_put_mem_region(ofbi->region);
+
                 if (r)
                         goto out;
         }
@@ -330,13 +337,11 @@ static ssize_t show_overlays_rotate(struct device *dev,
 {
         struct fb_info *fbi = dev_get_drvdata(dev);
         struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
         ssize_t l = 0;
         int t;
 
         if (!lock_fb_info(fbi))
                 return -ENODEV;
-        omapfb_lock(fbdev);
 
         for (t = 0; t < ofbi->num_overlays; t++) {
                 l += snprintf(buf + l, PAGE_SIZE - l, "%s%d",
@@ -345,7 +350,6 @@ static ssize_t show_overlays_rotate(struct device *dev,
 
         l += snprintf(buf + l, PAGE_SIZE - l, "\n");
 
-        omapfb_unlock(fbdev);
         unlock_fb_info(fbi);
 
         return l;
@@ -356,7 +360,6 @@ static ssize_t store_overlays_rotate(struct device *dev,
 {
         struct fb_info *fbi = dev_get_drvdata(dev);
         struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
         int num_ovls = 0, r, i;
         int len;
         bool changed = false;
@@ -368,7 +371,6 @@ static ssize_t store_overlays_rotate(struct device *dev,
 
         if (!lock_fb_info(fbi))
                 return -ENODEV;
-        omapfb_lock(fbdev);
 
         if (len > 0) {
                 char *p = (char *)buf;
@@ -405,7 +407,12 @@ static ssize_t store_overlays_rotate(struct device *dev,
                 for (i = 0; i < num_ovls; ++i)
                         ofbi->rotation[i] = rotation[i];
 
+                omapfb_get_mem_region(ofbi->region);
+
                 r = omapfb_apply_changes(fbi, 0);
+
+                omapfb_put_mem_region(ofbi->region);
+
                 if (r)
                         goto out;
 
@@ -414,7 +421,6 @@ static ssize_t store_overlays_rotate(struct device *dev,
 
         r = count;
 out:
-        omapfb_unlock(fbdev);
         unlock_fb_info(fbi);
 
         return r;
@@ -425,19 +431,8 @@ static ssize_t show_size(struct device *dev,
 {
         struct fb_info *fbi = dev_get_drvdata(dev);
         struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
-        int r;
 
-        if (!lock_fb_info(fbi))
-                return -ENODEV;
-        omapfb_lock(fbdev);
-
-        r = snprintf(buf, PAGE_SIZE, "%lu\n", ofbi->region->size);
-
-        omapfb_unlock(fbdev);
-        unlock_fb_info(fbi);
-
-        return r;
+        return snprintf(buf, PAGE_SIZE, "%lu\n", ofbi->region->size);
 }
 
 static ssize_t store_size(struct device *dev, struct device_attribute *attr,
@@ -460,15 +455,15 @@ static ssize_t store_size(struct device *dev, struct device_attribute *attr,
 
         if (!lock_fb_info(fbi))
                 return -ENODEV;
-        omapfb_lock(fbdev);
 
         if (display && display->driver->sync)
                 display->driver->sync(display);
 
-        mutex_lock(&fbi->mm_lock);
-
         rg = ofbi->region;
 
+        down_write_nested(&rg->lock, rg->id);
+        atomic_inc(&rg->lock_count);
+
         if (atomic_read(&rg->map_count)) {
                 r = -EBUSY;
                 goto out;
@@ -501,8 +496,9 @@ static ssize_t store_size(struct device *dev, struct device_attribute *attr,
 
         r = count;
 out:
-        mutex_unlock(&fbi->mm_lock);
-        omapfb_unlock(fbdev);
+        atomic_dec(&rg->lock_count);
+        up_write(&rg->lock);
+
         unlock_fb_info(fbi);
 
         return r;
@@ -513,19 +509,8 @@ static ssize_t show_phys(struct device *dev,
 {
         struct fb_info *fbi = dev_get_drvdata(dev);
         struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
-        int r;
 
-        if (!lock_fb_info(fbi))
-                return -ENODEV;
-        omapfb_lock(fbdev);
-
-        r = snprintf(buf, PAGE_SIZE, "%0x\n", ofbi->region->paddr);
-
-        omapfb_unlock(fbdev);
-        unlock_fb_info(fbi);
-
-        return r;
+        return snprintf(buf, PAGE_SIZE, "%0x\n", ofbi->region->paddr);
 }
 
 static ssize_t show_virt(struct device *dev,
@@ -541,20 +526,11 @@ static ssize_t show_upd_mode(struct device *dev,
                 struct device_attribute *attr, char *buf)
 {
         struct fb_info *fbi = dev_get_drvdata(dev);
-        struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
         enum omapfb_update_mode mode;
         int r;
 
-        if (!lock_fb_info(fbi))
-                return -ENODEV;
-        omapfb_lock(fbdev);
-
         r = omapfb_get_update_mode(fbi, &mode);
 
-        omapfb_unlock(fbdev);
-        unlock_fb_info(fbi);
-
         if (r)
                 return r;
 
@@ -565,8 +541,6 @@ static ssize_t store_upd_mode(struct device *dev, struct device_attribute *attr,
                 const char *buf, size_t count)
 {
         struct fb_info *fbi = dev_get_drvdata(dev);
-        struct omapfb_info *ofbi = FB2OFB(fbi);
-        struct omapfb2_device *fbdev = ofbi->fbdev;
         unsigned mode;
         int r;
 
@@ -574,17 +548,10 @@ static ssize_t store_upd_mode(struct device *dev, struct device_attribute *attr,
         if (r)
                 return r;
 
-        if (!lock_fb_info(fbi))
-                return -ENODEV;
-        omapfb_lock(fbdev);
-
         r = omapfb_set_update_mode(fbi, mode);
         if (r)
                 return r;
 
-        omapfb_unlock(fbdev);
-        unlock_fb_info(fbi);
-
         return count;
 }
 
diff --git a/drivers/video/omap2/omapfb/omapfb.h b/drivers/video/omap2/omapfb/omapfb.h
index 2b5264475ed4..623cd872a367 100644
--- a/drivers/video/omap2/omapfb/omapfb.h
+++ b/drivers/video/omap2/omapfb/omapfb.h
@@ -62,6 +62,8 @@ struct omapfb2_mem_region {
         bool            alloc;          /* allocated by the driver */
         bool            map;            /* kernel mapped by the driver */
         atomic_t        map_count;
+        struct rw_semaphore lock;
+        atomic_t        lock_count;
 };
 
 /* appended to fb_info */
@@ -189,4 +191,18 @@ static inline int omapfb_overlay_enable(struct omap_overlay *ovl,
                 return ovl->disable(ovl);
 }
 
+static inline struct omapfb2_mem_region *
+omapfb_get_mem_region(struct omapfb2_mem_region *rg)
+{
+        down_read_nested(&rg->lock, rg->id);
+        atomic_inc(&rg->lock_count);
+        return rg;
+}
+
+static inline void omapfb_put_mem_region(struct omapfb2_mem_region *rg)
+{
+        atomic_dec(&rg->lock_count);
+        up_read(&rg->lock);
+}
+
 #endif