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>
This commit is contained in:
Родитель
5798712d60
Коммит
7fc80b7bd6
|
@ -201,7 +201,6 @@ static int neoFindMode(int xres, int yres, int depth)
|
||||||
*
|
*
|
||||||
* Determine the closest clock frequency to the one requested.
|
* 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_N 127
|
||||||
#define MAX_D 31
|
#define MAX_D 31
|
||||||
#define MAX_F 1
|
#define MAX_F 1
|
||||||
|
@ -211,27 +210,24 @@ static void neoCalcVCLK(const struct fb_info *info,
|
||||||
{
|
{
|
||||||
int n, d, f;
|
int n, d, f;
|
||||||
int n_best = 0, d_best = 0, f_best = 0;
|
int n_best = 0, d_best = 0, f_best = 0;
|
||||||
long f_best_diff = (0x7ffff << 12); /* 20.12 */
|
long f_best_diff = 0x7ffff;
|
||||||
long f_target = (freq << 12) / 1000; /* 20.12 */
|
|
||||||
|
|
||||||
for (f = 0; f <= MAX_F; f++)
|
for (f = 0; f <= MAX_F; f++)
|
||||||
for (n = 0; n <= MAX_N; n++)
|
for (d = 0; d <= MAX_D; d++)
|
||||||
for (d = 0; d <= MAX_D; d++) {
|
for (n = 0; n <= MAX_N; n++) {
|
||||||
long f_out; /* 20.12 */
|
long f_out;
|
||||||
long f_diff; /* 20.12 */
|
long f_diff;
|
||||||
|
|
||||||
f_out =
|
f_out = ((14318 * (n + 1)) / (d + 1)) >> f;
|
||||||
((((n + 1) << 12) / ((d +
|
f_diff = abs(f_out - freq);
|
||||||
1) *
|
if (f_diff <= f_best_diff) {
|
||||||
(1 << f))) >> 12)
|
|
||||||
* REF_FREQ;
|
|
||||||
f_diff = abs(f_out - f_target);
|
|
||||||
if (f_diff < f_best_diff) {
|
|
||||||
f_best_diff = f_diff;
|
f_best_diff = f_diff;
|
||||||
n_best = n;
|
n_best = n;
|
||||||
d_best = d;
|
d_best = d;
|
||||||
f_best = f;
|
f_best = f;
|
||||||
}
|
}
|
||||||
|
if (f_out > freq)
|
||||||
|
break;
|
||||||
}
|
}
|
||||||
|
|
||||||
if (info->fix.accel == FB_ACCEL_NEOMAGIC_NM2200 ||
|
if (info->fix.accel == FB_ACCEL_NEOMAGIC_NM2200 ||
|
||||||
|
@ -248,11 +244,11 @@ static void neoCalcVCLK(const struct fb_info *info,
|
||||||
par->VCLK3Denominator = d_best;
|
par->VCLK3Denominator = d_best;
|
||||||
|
|
||||||
#ifdef NEOFB_DEBUG
|
#ifdef NEOFB_DEBUG
|
||||||
printk("neoVCLK: f:%d NumLow=%d NumHi=%d Den=%d Df=%d\n",
|
printk(KERN_DEBUG "neoVCLK: f:%ld NumLow=%d NumHi=%d Den=%d Df=%ld\n",
|
||||||
f_target >> 12,
|
freq,
|
||||||
par->VCLK3NumeratorLow,
|
par->VCLK3NumeratorLow,
|
||||||
par->VCLK3NumeratorHigh,
|
par->VCLK3NumeratorHigh,
|
||||||
par->VCLK3Denominator, f_best_diff >> 12);
|
par->VCLK3Denominator, f_best_diff);
|
||||||
#endif
|
#endif
|
||||||
}
|
}
|
||||||
|
|
||||||
|
|
Загрузка…
Ссылка в новой задаче