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    Subject[PATCH 6/8] omapfb: Condition mutex acquisition
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    Date
    From: Sergio Aguirre <saaguirre@ti.com>

    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>
    Signed-off-by: Tony Lindgren <tony@atomide.com>
    ---
    drivers/video/omap/omapfb_main.c | 22 ++++++++++++++--------
    1 files changed, 14 insertions(+), 8 deletions(-)

    diff --git a/drivers/video/omap/omapfb_main.c b/drivers/video/omap/omapfb_main.c
    index 125e605..0d0c8c8 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)


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