diff options
Diffstat (limited to 'src/smi_501.c')
| -rw-r--r-- | src/smi_501.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/src/smi_501.c b/src/smi_501.c index 8bc0d34..4e78a75 100644 --- a/src/smi_501.c +++ b/src/smi_501.c @@ -620,7 +620,7 @@ SMI501_FindClock(double clock, int32_t max_divider, Bool has1xclck, double diff, best, mclk; int32_t multiplier, divider, shift, xclck; - /* The Crystal input frequency is 24Mhz, and can have be multiplied + /* The Crystal input frequency is 24Mhz, and can be multiplied * by 12 or 14 (actually, there are other values, see TIMING_CTL, * MMIO 0x068) */ @@ -664,6 +664,7 @@ SMI501_FindPLLClock(double clock, int32_t *m, int32_t *n, int32_t *xclck) { int32_t M, N, K; double diff, best; + double frequency; /* This method, available only on the 502 is intended to cover the * disadvantage of the other method where certain modes cannot be @@ -685,10 +686,18 @@ SMI501_FindPLLClock(double clock, int32_t *m, int32_t *n, int32_t *xclck) */ best = 0x7fffffff; + /* FIXME: The 12 multiplier was a wild guess (but it doesn't work with + * a 14 modifier, i.e. 288 works, but not 336), and actually it corrects + * the "flicker" on the panel, and will properly display output on a + * secondary panel/crt. + * So, should bug SMI about incorrect (non official) information, and + * also ask for better definition of K... + */ + frequency = 12 * 24 * 1000.0; for (N = 2; N <= 24; N++) { for (K = 1; K <= 2; K++) { - M = clock * K * N / 24 / 1000.0; - diff = (24 * 1000.0 * M / N) - (clock * K); + M = (clock * K) / frequency * N; + diff = (frequency * M / N) - (clock * K); /* Ensure M is larger then 0 and fits in 7 bits */ if (M > 0 && M < 0x80 && fabs(diff) < best) { *m = M; @@ -703,7 +712,7 @@ SMI501_FindPLLClock(double clock, int32_t *m, int32_t *n, int32_t *xclck) xf86ErrorFVerb(VERBLEV, "\tMatching alternate clock %5.2f, diff %5.2f (%d/%d/%d)\n", - 24 * 1000.0 * *m / *n / (*xclck ? 1 : 2), best, + frequency * *m / *n / (*xclck ? 1 : 2), best, *m, *n, *xclck); return (best); |