s3fb: maximize virtual vertical size for fast scrolling

Maximize virtual vertical framebuffer size during init to allow fast scrolling
(accelerated by panning).

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Acked-by: Ondrej Zajicek <santiago@crfreenet.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/video/s3fb.c b/drivers/video/s3fb.c
index 55a94b94a326..9f9be9f37f2e 100644
--- a/drivers/video/s3fb.c
+++ b/drivers/video/s3fb.c
@@ -1053,6 +1053,14 @@ static int __devinit s3_pci_probe(struct pci_dev *dev, const struct pci_device_i
                 goto err_find_mode;
         }
 
+        /* maximize virtual vertical size for fast scrolling */
+        info->var.yres_virtual = info->fix.smem_len * 8 /
+                        (info->var.bits_per_pixel * info->var.xres_virtual);
+        if (info->var.yres_virtual < info->var.yres) {
+                dev_err(info->device, "virtual vertical size smaller than real\n");
+                goto err_find_mode;
+        }
+
         rc = fb_alloc_cmap(&info->cmap, 256, 0);
         if (rc < 0) {
                 dev_err(info->device, "cannot allocate colormap\n");