pxafb: use passed fb_var_screeninfo struct in pxafb_pan_display()

pxafb_pan_display() used to ignore the fb_var_screeninfo parameter. Now
pass it to setup_base_frame() instead of pulling default values out of
fb_info.

And the original patch has an issue of pxafb_pan_display() paying only
attention to the 'var' parameter passed in, and Ville Syrjälä pointed
out, this is potentially dangerous as user could pass in any other
screeninfo parameters as well, and not only such that are relevant for
display panning. This is fixed by limiting the arguments actually used
to .xoffset, .yoffset and .vmode & FB_VMODE_YWRAP.
Signed-off-by: Sven Neumann <s.neumann@raumfeld.com>
Cc: Ville Syrjälä <syrjala@sci.fi>
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>

drivers/video/pxafb.c

@@ -80,7 +80,8 @@
 static int pxafb_activate_var(struct fb_var_screeninfo *var,
 				struct pxafb_info *);
 static void set_ctrlr_state(struct pxafb_info *fbi, u_int state);
-static void setup_base_frame(struct pxafb_info *fbi, int branch);
+static void setup_base_frame(struct pxafb_info *fbi,
+                             struct fb_var_screeninfo *var, int branch);
 static int setup_frame_dma(struct pxafb_info *fbi, int dma, int pal,
 			   unsigned long offset, size_t size);
 
@@ -531,12 +532,22 @@ static int pxafb_pan_display(struct fb_var_screeninfo *var,
 			     struct fb_info *info)
 {
 	struct pxafb_info *fbi = (struct pxafb_info *)info;
+	struct fb_var_screeninfo newvar;
 	int dma = DMA_MAX + DMA_BASE;
 
 	if (fbi->state != C_ENABLE)
 		return 0;
 
-	setup_base_frame(fbi, 1);
+	/* Only take .xoffset, .yoffset and .vmode & FB_VMODE_YWRAP from what
+	 * was passed in and copy the rest from the old screeninfo.
+	 */
+	memcpy(&newvar, &fbi->fb.var, sizeof(newvar));
+	newvar.xoffset = var->xoffset;
+	newvar.yoffset = var->yoffset;
+	newvar.vmode &= ~FB_VMODE_YWRAP;
+	newvar.vmode |= var->vmode & FB_VMODE_YWRAP;
+
+	setup_base_frame(fbi, &newvar, 1);
 
 	if (fbi->lccr0 & LCCR0_SDS)
 		lcd_writel(fbi, FBR1, fbi->fdadr[dma + 1] | 0x1);
@@ -1052,9 +1063,10 @@ static int setup_frame_dma(struct pxafb_info *fbi, int dma, int pal,
 	return 0;
 }
 
-static void setup_base_frame(struct pxafb_info *fbi, int branch)
+static void setup_base_frame(struct pxafb_info *fbi,
+                             struct fb_var_screeninfo *var,
+                             int branch)
 {
-	struct fb_var_screeninfo *var = &fbi->fb.var;
 	struct fb_fix_screeninfo *fix = &fbi->fb.fix;
 	int nbytes, dma, pal, bpp = var->bits_per_pixel;
 	unsigned long offset;
@@ -1332,7 +1344,7 @@ static int pxafb_activate_var(struct fb_var_screeninfo *var,
 #endif
 		setup_parallel_timing(fbi, var);
 
-	setup_base_frame(fbi, 0);
+	setup_base_frame(fbi, var, 0);
 
 	fbi->reg_lccr0 = fbi->lccr0 |
 		(LCCR0_LDM | LCCR0_SFM | LCCR0_IUM | LCCR0_EFM |