tridentfb: fix clock settings for older Trident 96XX chips

The Xorg code shows that Trident models 9660, 9680 and 9682 require a
different clock setting method.  Add the second clock setting method for older
models.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 23 insertions, 8 deletions

diff --git a/drivers/video/tridentfb.c b/drivers/video/tridentfb.c
index f3153a82f926..8ee4261abf3b 100644
--- a/drivers/video/tridentfb.c
+++ b/drivers/video/tridentfb.c
@@ -85,6 +85,11 @@ MODULE_PARM_DESC(fp, "Define if flatpanel is connected");
 module_param(crt, int, 0);
 MODULE_PARM_DESC(crt, "Define if CRT is connected");
 
+static int is_oldclock(int id)
+{
+        return (id == TGUI9660);
+}
+
 static int is_blade(int id)
 {
         return  (id == BLADE3D) ||
@@ -659,23 +664,33 @@ static void set_screen_start(struct tridentfb_par *par, int base)
 static void set_vclk(struct tridentfb_par *par, unsigned long freq)
 {
         int m, n, k;
-        unsigned long f, fi, d, di;
-        unsigned char lo = 0, hi = 0;
+        unsigned long fi, d, di;
+        unsigned char best_m = 0, best_n = 0, best_k = 0;
+        unsigned char hi, lo;
 
         d = 20000;
-        for (k = 2; k >= 0; k--)
-                for (m = 0; m < 63; m++)
-                        for (n = 0; n < 128; n++) {
+        for (k = 1; k >= 0; k--)
+                for (m = 0; m < 32; m++)
+                        for (n = 0; n < 122; n++) {
                                 fi = ((14318l * (n + 8)) / (m + 2)) >> k;
                                 if ((di = abs(fi - freq)) < d) {
                                         d = di;
-                                        f = fi;
-                                        lo = n;
-                                        hi = (k << 6) | m;
+                                        best_n = n;
+                                        best_m = m;
+                                        best_k = k;
                                 }
                                 if (fi > freq)
                                         break;
                         }
+
+        if (is_oldclock(par->chip_id)) {
+                lo = best_n | (best_m << 7);
+                hi = (best_m >> 1) | (best_k << 4);
+        } else {
+                lo = best_n;
+                hi = best_m | (best_k << 6);
+        }
+
         if (is3Dchip(par->chip_id)) {
                 vga_mm_wseq(par->io_virt, ClockHigh, hi);
                 vga_mm_wseq(par->io_virt, ClockLow, lo);