omapfb: Condition mutex acquisition

This fixes a bug introduced by this commit ID:

  commit 537a1bf059fa312355696fa6db80726e655e7f17
  Author: Krzysztof Helt <krzysztof.h1@wp.pl>
  Date:   Tue Jun 30 11:41:29 2009 -0700

    fbdev: add mutex for fb_mmap locking

In which a mutex was added when changing smem_start and smem_len fields,
so the mutex inside the fb_mmap() call is actually used.

The problem was that set_fb_fix, which modifies the above 2 fields,
was called before and after registering the framebuffer,
which when used before registration, lead to a failed attempt to
use an uninitialized mutex.

Solution: Don't use mutex before framebuffer registration.

Signed-off-by: Sergio Aguirre <saaguirre@ti.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>
Acked-by: Imre Deak <imre.deak@nokia.com>
Tested-by: Cory Maccarrone <darkstar6262@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

1 files changed, 14 insertions, 8 deletions

diff --git a/drivers/video/omap/omapfb_main.c b/drivers/video/omap/omapfb_main.c
index 125e605b8c68..0d0c8c8b9b56 100644
--- a/drivers/video/omap/omapfb_main.c
+++ b/drivers/video/omap/omapfb_main.c
@@ -393,7 +393,7 @@ static void omapfb_sync(struct fb_info *fbi)
  * Set fb_info.fix fields and also updates fbdev.
  * When calling this fb_info.var must be set up already.
  */
-static void set_fb_fix(struct fb_info *fbi)
+static void set_fb_fix(struct fb_info *fbi, int from_init)
 {
         struct fb_fix_screeninfo *fix = &fbi->fix;
         struct fb_var_screeninfo *var = &fbi->var;
@@ -403,10 +403,16 @@ static void set_fb_fix(struct fb_info *fbi)
 
         rg = &plane->fbdev->mem_desc.region[plane->idx];
         fbi->screen_base        = rg->vaddr;
-        mutex_lock(&fbi->mm_lock);
-        fix->smem_start         = rg->paddr;
-        fix->smem_len           = rg->size;
-        mutex_unlock(&fbi->mm_lock);
+
+        if (!from_init) {
+                mutex_lock(&fbi->mm_lock);
+                fix->smem_start         = rg->paddr;
+                fix->smem_len           = rg->size;
+                mutex_unlock(&fbi->mm_lock);
+        } else {
+                fix->smem_start         = rg->paddr;
+                fix->smem_len           = rg->size;
+        }
 
         fix->type = FB_TYPE_PACKED_PIXELS;
         bpp = var->bits_per_pixel;
@@ -704,7 +710,7 @@ static int omapfb_set_par(struct fb_info *fbi)
         int r = 0;
 
         omapfb_rqueue_lock(fbdev);
-        set_fb_fix(fbi);
+        set_fb_fix(fbi, 0);
         r = ctrl_change_mode(fbi);
         omapfb_rqueue_unlock(fbdev);
 
@@ -904,7 +910,7 @@ static int omapfb_setup_mem(struct fb_info *fbi, struct omapfb_mem_info *mi)
                 if (old_size != size) {
                         if (size) {
                                 memcpy(&fbi->var, new_var, sizeof(fbi->var));
-                                set_fb_fix(fbi);
+                                set_fb_fix(fbi, 0);
                         } else {
                                 /*
                                  * Set these explicitly to indicate that the
@@ -1504,7 +1510,7 @@ static int fbinfo_init(struct omapfb_device *fbdev, struct fb_info *info)
         var->bits_per_pixel = fbdev->panel->bpp;
 
         set_fb_var(info, var);
-        set_fb_fix(info);
+        set_fb_fix(info, 1);
 
         r = fb_alloc_cmap(&info->cmap, 16, 0);
         if (r != 0)