diff options
| author | Krzysztof Helt <krzysztof.h1@wp.pl> | 2008-07-24 06:31:44 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-07-24 19:47:41 +0200 |
| commit | 7fc80b7bd682b47825e806018cca8ff7dc6bb55a (patch) | |
| tree | d408bf73887f4788e0d5e70c91320fff1391f624 /drivers/video | |
| parent | drivers/video/amifb.c cleanups (diff) | |
| download | linux-7fc80b7bd682b47825e806018cca8ff7dc6bb55a.tar.xz linux-7fc80b7bd682b47825e806018cca8ff7dc6bb55a.zip | |
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>
Diffstat (limited to 'drivers/video')
| -rw-r--r-- | drivers/video/neofb.c | 32 |
1 files changed, 14 insertions, 18 deletions
diff --git a/drivers/video/neofb.c b/drivers/video/neofb.c index 5246b0402d76..b033e5a4dc86 100644 --- a/drivers/video/neofb.c +++ b/drivers/video/neofb.c @@ -201,7 +201,6 @@ static int neoFindMode(int xres, int yres, int depth) * * 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 @@ static void neoCalcVCLK(const struct fb_info *info, { 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 */ - - 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) { + for (d = 0; d <= MAX_D; d++) + for (n = 0; n <= MAX_N; n++) { + long f_out; + long f_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 @@ static void neoCalcVCLK(const struct fb_info *info, 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 } |