1 files changed, 47 insertions, 8 deletions

diff --git a/drivers/video/mx3fb.c b/drivers/video/mx3fb.c
index eec0d7b748eb..c89f8a8d36d2 100644
--- a/drivers/video/mx3fb.c
+++ b/drivers/video/mx3fb.c
@@ -269,7 +269,7 @@ struct mx3fb_info {
         dma_cookie_t                    cookie;
         struct scatterlist              sg[2];
 
-        u32                             sync;   /* preserve var->sync flags */
+        struct fb_var_screeninfo        cur_var; /* current var info */
 };
 
 static void mx3fb_dma_done(void *);
@@ -698,9 +698,29 @@ static void mx3fb_dma_done(void *arg)
         complete(&mx3_fbi->flip_cmpl);
 }
 
+static bool mx3fb_must_set_par(struct fb_info *fbi)
+{
+        struct mx3fb_info *mx3_fbi = fbi->par;
+        struct fb_var_screeninfo old_var = mx3_fbi->cur_var;
+        struct fb_var_screeninfo new_var = fbi->var;
+
+        if ((fbi->var.activate & FB_ACTIVATE_FORCE) &&
+            (fbi->var.activate & FB_ACTIVATE_MASK) == FB_ACTIVATE_NOW)
+                return true;
+
+        /*
+         * Ignore xoffset and yoffset update,
+         * because pan display handles this case.
+         */
+        old_var.xoffset = new_var.xoffset;
+        old_var.yoffset = new_var.yoffset;
+
+        return !!memcmp(&old_var, &new_var, sizeof(struct fb_var_screeninfo));
+}
+
 static int __set_par(struct fb_info *fbi, bool lock)
 {
-        u32 mem_len;
+        u32 mem_len, cur_xoffset, cur_yoffset;
         struct ipu_di_signal_cfg sig_cfg;
         enum ipu_panel mode = IPU_PANEL_TFT;
         struct mx3fb_info *mx3_fbi = fbi->par;
@@ -780,8 +800,25 @@ static int __set_par(struct fb_info *fbi, bool lock)
         video->out_height       = fbi->var.yres;
         video->out_stride       = fbi->var.xres_virtual;
 
-        if (mx3_fbi->blank == FB_BLANK_UNBLANK)
+        if (mx3_fbi->blank == FB_BLANK_UNBLANK) {
                 sdc_enable_channel(mx3_fbi);
+                /*
+                 * sg[0] points to fb smem_start address
+                 * and is actually active in controller.
+                 */
+                mx3_fbi->cur_var.xoffset = 0;
+                mx3_fbi->cur_var.yoffset = 0;
+        }
+
+        /*
+         * Preserve xoffset and yoffest in case they are
+         * inactive in controller as fb is blanked.
+         */
+        cur_xoffset = mx3_fbi->cur_var.xoffset;
+        cur_yoffset = mx3_fbi->cur_var.yoffset;
+        mx3_fbi->cur_var = fbi->var;
+        mx3_fbi->cur_var.xoffset = cur_xoffset;
+        mx3_fbi->cur_var.yoffset = cur_yoffset;
 
         return 0;
 }
@@ -802,7 +839,7 @@ static int mx3fb_set_par(struct fb_info *fbi)
 
         mutex_lock(&mx3_fbi->mutex);
 
-        ret = __set_par(fbi, true);
+        ret = mx3fb_must_set_par(fbi) ? __set_par(fbi, true) : 0;
 
         mutex_unlock(&mx3_fbi->mutex);
 
@@ -901,8 +938,8 @@ static int mx3fb_check_var(struct fb_var_screeninfo *var, struct fb_info *fbi)
         var->grayscale = 0;
 
         /* Preserve sync flags */
-        var->sync |= mx3_fbi->sync;
-        mx3_fbi->sync |= var->sync;
+        var->sync |= mx3_fbi->cur_var.sync;
+        mx3_fbi->cur_var.sync |= var->sync;
 
         return 0;
 }
@@ -1043,8 +1080,8 @@ static int mx3fb_pan_display(struct fb_var_screeninfo *var,
                 return -EINVAL;
         }
 
-        if (fbi->var.xoffset == var->xoffset &&
-            fbi->var.yoffset == var->yoffset)
+        if (mx3_fbi->cur_var.xoffset == var->xoffset &&
+            mx3_fbi->cur_var.yoffset == var->yoffset)
                 return 0;       /* No change, do nothing */
 
         y_bottom = var->yoffset;
@@ -1127,6 +1164,8 @@ static int mx3fb_pan_display(struct fb_var_screeninfo *var,
         else
                 fbi->var.vmode &= ~FB_VMODE_YWRAP;
 
+        mx3_fbi->cur_var = fbi->var;
+
         mutex_unlock(&mx3_fbi->mutex);
 
         dev_dbg(fbi->device, "Update complete\n");