neofb: simplify clock calculation
There is nothing to gain by converting value in kHz to fixed point MHz.
Just calculate everything in kHz.
A reorder of the loop allows reducing number of iterations (check if
frequency is not too high already).
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>
diff --git a/drivers/video/neofb.c b/drivers/video/neofb.c
index 5246b04..b033e5a 100644
--- a/drivers/video/neofb.c
+++ b/drivers/video/neofb.c
@@ -201,7 +201,6 @@
*
* Determine the closest clock frequency to the one requested.
*/
-#define REF_FREQ 0xe517 /* 14.31818 in 20.12 fixed point */
#define MAX_N 127
#define MAX_D 31
#define MAX_F 1
@@ -211,27 +210,24 @@
{
int n, d, f;
int n_best = 0, d_best = 0, f_best = 0;
- long f_best_diff = (0x7ffff << 12); /* 20.12 */
- long f_target = (freq << 12) / 1000; /* 20.12 */
+ long f_best_diff = 0x7ffff;
for (f = 0; f <= MAX_F; f++)
- for (n = 0; n <= MAX_N; n++)
- for (d = 0; d <= MAX_D; d++) {
- long f_out; /* 20.12 */
- long f_diff; /* 20.12 */
+ for (d = 0; d <= MAX_D; d++)
+ for (n = 0; n <= MAX_N; n++) {
+ long f_out;
+ long f_diff;
- f_out =
- ((((n + 1) << 12) / ((d +
- 1) *
- (1 << f))) >> 12)
- * REF_FREQ;
- f_diff = abs(f_out - f_target);
- if (f_diff < f_best_diff) {
+ f_out = ((14318 * (n + 1)) / (d + 1)) >> f;
+ f_diff = abs(f_out - freq);
+ if (f_diff <= f_best_diff) {
f_best_diff = f_diff;
n_best = n;
d_best = d;
f_best = f;
}
+ if (f_out > freq)
+ break;
}
if (info->fix.accel == FB_ACCEL_NEOMAGIC_NM2200 ||
@@ -248,11 +244,11 @@
par->VCLK3Denominator = d_best;
#ifdef NEOFB_DEBUG
- printk("neoVCLK: f:%d NumLow=%d NumHi=%d Den=%d Df=%d\n",
- f_target >> 12,
+ printk(KERN_DEBUG "neoVCLK: f:%ld NumLow=%d NumHi=%d Den=%d Df=%ld\n",
+ freq,
par->VCLK3NumeratorLow,
par->VCLK3NumeratorHigh,
- par->VCLK3Denominator, f_best_diff >> 12);
+ par->VCLK3Denominator, f_best_diff);
#endif
}