s3fb: do not allow incorrect pixclock settings

This patch adds check if selected pixclock is valid (is in the PLL range).

Previously, if the pixclock could not be set, the new mode resolution was set
but pixclock was not set which led to incorrect timings sent to monitor.

[adaplas]
Fixed a few misplaced curly braces.
Signed-off-by: NKrzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: NAntonino Daplas <adaplas@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/video/s3fb.c

@@ -400,6 +400,7 @@ static int s3fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 {
 	struct s3fb_info *par = info->par;
 	int rv, mem, step;
+	u16 m, n, r;
 
 	/* Find appropriate format */
 	rv = svga_match_format (s3fb_formats, var, NULL);
@@ -427,20 +428,26 @@ static int s3fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 
 	/* Check whether have enough memory */
 	mem = ((var->bits_per_pixel * var->xres_virtual) >> 3) * var->yres_virtual;
-	if (mem > info->screen_size)
-	{
+	if (mem > info->screen_size) {
 		printk(KERN_ERR "fb%d: not enough framebuffer memory (%d kB requested , %d kB available)\n",
 			info->node, mem >> 10, (unsigned int) (info->screen_size >> 10));
 		return -EINVAL;
 	}
 
 	rv = svga_check_timings (&s3_timing_regs, var, info->node);
-	if (rv < 0)
-	{
+	if (rv < 0) {
 		printk(KERN_ERR "fb%d: invalid timings requested\n", info->node);
 		return rv;
 	}
 
+	rv = svga_compute_pll(&s3_pll, PICOS2KHZ(var->pixclock), &m, &n, &r,
+				info->node);
+	if (rv < 0) {
+		printk(KERN_ERR "fb%d: invalid pixclock value requested\n",
+			info->node);
+		return rv;
+	}
+
 	return 0;
 }