OMAP: DSS2: OMAPFB: Convert the memory region locking to rwsem

R/W semaphore is a good fit for the memory region locking pattern.
So use it.
Signed-off-by: Ville Syrjälä <ville.syrjala@nokia.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>

drivers/video/omap2/omapfb/omapfb-ioctl.c

@@ -198,13 +198,7 @@ static int omapfb_setup_mem(struct fb_info *fbi, struct omapfb_mem_info *mi)
 
 	rg = ofbi->region;
 
-	/* FIXME probably should be a rwsem ... */
-	mutex_lock(&rg->mtx);
-	while (rg->ref) {
-		mutex_unlock(&rg->mtx);
-		schedule();
-		mutex_lock(&rg->mtx);
-	}
+	down_write(&rg->lock);
 
 	if (atomic_read(&rg->map_count)) {
 		r = -EBUSY;
@@ -235,7 +229,7 @@ static int omapfb_setup_mem(struct fb_info *fbi, struct omapfb_mem_info *mi)
 	}
 
  out:
-	mutex_unlock(&rg->mtx);
+	up_write(&rg->lock);
 
 	return r;
 }

drivers/video/omap2/omapfb/omapfb-main.c

@@ -1930,7 +1930,7 @@ static int omapfb_create_framebuffers(struct omapfb2_device *fbdev)
 
 		ofbi->region = &fbdev->regions[i];
 		ofbi->region->id = i;
-		mutex_init(&ofbi->region->mtx);
+		init_rwsem(&ofbi->region->lock);
 
 		/* assign these early, so that fb alloc can use them */
 		ofbi->rotation_type = def_vrfb ? OMAP_DSS_ROT_VRFB :

drivers/video/omap2/omapfb/omapfb-sysfs.c

@@ -452,13 +452,7 @@ static ssize_t store_size(struct device *dev, struct device_attribute *attr,
 
 	rg = ofbi->region;
 
-	/* FIXME probably should be a rwsem ... */
-	mutex_lock(&rg->mtx);
-	while (rg->ref) {
-		mutex_unlock(&rg->mtx);
-		schedule();
-		mutex_lock(&rg->mtx);
-	}
+	down_write(&rg->lock);
 
 	if (atomic_read(&rg->map_count)) {
 		r = -EBUSY;
@@ -490,7 +484,7 @@ static ssize_t store_size(struct device *dev, struct device_attribute *attr,
 
 	r = count;
 out:
-	mutex_unlock(&rg->mtx);
+	up_write(&rg->lock);
 
 	unlock_fb_info(fbi);
 

drivers/video/omap2/omapfb/omapfb.h

@@ -27,6 +27,8 @@
 #define DEBUG
 #endif
 
+#include <linux/rwsem.h>
+
 #include <plat/display.h>
 
 #ifdef DEBUG
@@ -52,9 +54,8 @@ struct omapfb2_mem_region {
 	u8		type;		/* OMAPFB_PLANE_MEM_* */
 	bool		alloc;		/* allocated by the driver */
 	bool		map;		/* kernel mapped by the driver */
-	struct mutex    mtx;
-	unsigned int    ref;
 	atomic_t	map_count;
+	struct rw_semaphore lock;
 };
 
 /* appended to fb_info */
@@ -164,17 +165,13 @@ static inline int omapfb_overlay_enable(struct omap_overlay *ovl,
 static inline struct omapfb2_mem_region *
 omapfb_get_mem_region(struct omapfb2_mem_region *rg)
 {
-	mutex_lock(&rg->mtx);
-	rg->ref++;
-	mutex_unlock(&rg->mtx);
+	down_read(&rg->lock);
 	return rg;
 }
 
 static inline void omapfb_put_mem_region(struct omapfb2_mem_region *rg)
 {
-	mutex_lock(&rg->mtx);
-	rg->ref--;
-	mutex_unlock(&rg->mtx);
+	up_read(&rg->lock);
 }
 
 #endif