OMAPFB: simplify locking

Kernel lock verification code has lately detected possible circular
locking in omapfb. The exact problem is unclear, but omapfb's current
locking seems to be overly complex.

This patch simplifies the locking in the following ways:

- Remove explicit omapfb mem region locking. I couldn't figure out the
  need for this, as long as we take care to take omapfb lock.

- Get omapfb lock always, even if the operation is possibly only related
  to one fb_info. Better safe than sorry, and normally there's only one
  user for the fb so this shouldn't matter.

- Make sure fb_info lock is taken first, then omapfb lock.

With this patch the warnings about possible circular locking does not
happen anymore.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>

1 files changed, 10 insertions, 30 deletions

diff --git a/drivers/video/omap2/omapfb/omapfb-main.c b/drivers/video/omap2/omapfb/omapfb-main.c
index 85130fa7ae5a..708f2cf90204 100644
--- a/drivers/video/omap2/omapfb/omapfb-main.c
+++ b/drivers/video/omap2/omapfb/omapfb-main.c
@@ -672,8 +672,6 @@ 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");
@@ -855,8 +853,6 @@ 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;
@@ -948,8 +944,6 @@ 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];
 
@@ -1008,15 +1002,16 @@ 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_get_mem_region(ofbi->region);
+	omapfb_lock(fbdev);
 
 	r = check_fb_var(fbi, var);
 
-	omapfb_put_mem_region(ofbi->region);
+	omapfb_unlock(fbdev);
 
 	return r;
 }
@@ -1025,11 +1020,12 @@ 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_get_mem_region(ofbi->region);
+	omapfb_lock(fbdev);
 
 	set_fb_fix(fbi);
 
@@ -1040,7 +1036,7 @@ static int omapfb_set_par(struct fb_info *fbi)
 	r = omapfb_apply_changes(fbi, 0);
 
  out:
-	omapfb_put_mem_region(ofbi->region);
+	omapfb_unlock(fbdev);
 
 	return r;
 }
@@ -1049,6 +1045,7 @@ 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;
 
@@ -1064,11 +1061,11 @@ static int omapfb_pan_display(struct fb_var_screeninfo *var,
 
 	fbi->var = new_var;
 
-	omapfb_get_mem_region(ofbi->region);
+	omapfb_lock(fbdev);
 
 	r = omapfb_apply_changes(fbi, 0);
 
-	omapfb_put_mem_region(ofbi->region);
+	omapfb_unlock(fbdev);
 
 	return r;
 }
@@ -1077,18 +1074,14 @@ 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 = {
@@ -1112,7 +1105,7 @@ static int omapfb_mmap(struct fb_info *fbi, struct vm_area_struct *vma)
 		return -EINVAL;
 	off = vma->vm_pgoff << PAGE_SHIFT;
 
-	rg = omapfb_get_mem_region(ofbi->region);
+	rg = ofbi->region;
 
 	start = omapfb_get_region_paddr(ofbi);
 	len = fix->smem_len;
@@ -1140,13 +1133,9 @@ 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;
 }
 
@@ -1914,7 +1903,6 @@ 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 :
@@ -1946,12 +1934,8 @@ 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;
@@ -1983,12 +1967,8 @@ 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;