mx3fb: support pan display with fb_set_var

Users may call FBIOPUT_VSCREENINFO ioctrl to do pan display.
This ioctrl relies on fb_set_var() to do the job. fb_set_var()
calls the custom fb_set_par() method and then calls the custom
fb_pan_display() method. Before calling the custom fb_pan_display()
method, info->var is already updated from the new *var in fb_set_var().
And, the custom fb_pan_display() method checks if xoffset and yoffset
in info->var and the new *var are different before doing actual panning,
which prevents the panning from happening within fb_set_var() context.
This patch caches the current var info locally in mx3fb driver so that
pan display with fb_set_var is supported.

Signed-off-by: Liu Ying <Ying.Liu@freescale.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

1 files changed, 26 insertions, 7 deletions

diff --git a/drivers/video/mx3fb.c b/drivers/video/mx3fb.c
index eec0d7b748eb..da1d052a18a5 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 *);
@@ -700,7 +700,7 @@ static void mx3fb_dma_done(void *arg)
 
 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 +780,25 @@ 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;
 }
@@ -901,8 +918,8 @@ 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 +1060,8 @@ 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 +1144,8 @@ 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");