tridentfb: improve check_var function

Do some additional checks (like pixelclock versus ramdac speed) to
eliminate modes which do not work.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/video/tridentfb.c b/drivers/video/tridentfb.c
index 6b3bb1e20738..62701c5570fd 100644
--- a/drivers/video/tridentfb.c
+++ b/drivers/video/tridentfb.c
@@ -829,6 +829,7 @@ static int tridentfb_check_var(struct fb_var_screeninfo *var,
 {
         struct tridentfb_par *par = info->par;
         int bpp = var->bits_per_pixel;
+        int ramdac = 230000; /* 230MHz for most 3D chips */
         debug("enter\n");
 
         /* check color depth */
@@ -837,6 +838,12 @@ static int tridentfb_check_var(struct fb_var_screeninfo *var,
         /* check whether resolution fits on panel and in memory */
         if (par->flatpanel && nativex && var->xres > nativex)
                 return -EINVAL;
+        /* various resolution checks */
+        var->xres = (var->xres + 7) & ~0x7;
+        if (var->xres != var->xres_virtual)
+                var->xres_virtual = var->xres;
+        if (var->yres > var->yres_virtual)
+                var->yres_virtual = var->yres;
         if (var->xres * var->yres_virtual * bpp / 8 > info->fix.smem_len)
                 return -EINVAL;
 
@@ -868,6 +875,33 @@ static int tridentfb_check_var(struct fb_var_screeninfo *var,
         default:
                 return -EINVAL;
         }
+
+        if (is_xp(par->chip_id))
+                ramdac = 350000;
+
+        switch (par->chip_id) {
+        case TGUI9440:
+                ramdac = 90000;
+                break;
+        case CYBER9320:
+        case TGUI9660:
+                ramdac = 135000;
+                break;
+        case PROVIDIA9685:
+        case CYBER9388:
+        case CYBER9382:
+        case CYBER9385:
+                ramdac = 170000;
+                break;
+        }
+
+        /* The clock is doubled for 32 bpp */
+        if (bpp == 32)
+                ramdac /= 2;
+
+        if (PICOS2KHZ(var->pixclock) > ramdac)
+                return -EINVAL;
+
         debug("exit\n");
 
         return 0;