diff options
| author | Krzysztof Helt <krzysztof.h1@wp.pl> | 2008-05-12 14:02:11 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-05-13 08:02:24 -0700 |
| commit | 3f275ea3086054205795972b8e87f2046fd3de98 (patch) | |
| tree | 5bdb37cf662a9998f888d6431766065ca458d474 /drivers/video | |
| parent | 6fb488239cd8750cc818197d6c346409c0e8d330 (diff) | |
tridentfb: improve clock setting accuracy
Improve clock calculation precision (to kHz from MHz) and removes parameter
field vclk from the tridentfb_par structure.
Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
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/tridentfb.c | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/drivers/video/tridentfb.c b/drivers/video/tridentfb.c index 982eeee0ae9..beefab2992c 100644 --- a/drivers/video/tridentfb.c +++ b/drivers/video/tridentfb.c @@ -27,7 +27,6 @@ #define VERSION "0.7.8-NEWAPI" struct tridentfb_par { - int vclk; /* in MHz */ void __iomem *io_virt; /* iospace virtual memory address */ }; @@ -669,27 +668,26 @@ static void set_screen_start(int base) (read3X4(CRTHiOrd) & 0xF8) | ((base & 0xE0000) >> 17)); } -/* Use 20.12 fixed-point for NTSC value and frequency calculation */ -#define calc_freq(n, m, k) ( ((unsigned long)0xE517 * (n + 8) / ((m + 2) * (1 << k))) >> 12 ) - /* Set dotclock frequency */ -static void set_vclk(int freq) +static void set_vclk(unsigned long freq) { int m, n, k; - int f, fi, d, di; + unsigned long f, fi, d, di; unsigned char lo = 0, hi = 0; - d = 20; + d = 20000; for (k = 2; k >= 0; k--) for (m = 0; m < 63; m++) for (n = 0; n < 128; n++) { - fi = calc_freq(n, m, k); + fi = ((14318l * (n + 8)) / (m + 2)) >> k; if ((di = abs(fi - freq)) < d) { d = di; f = fi; lo = n; hi = (k << 6) | m; } + if (fi > freq) + break; } if (chip3D) { write3C4(ClockHigh, hi); @@ -888,6 +886,8 @@ static int tridentfb_set_par(struct fb_info *info) struct fb_var_screeninfo *var = &info->var; int bpp = var->bits_per_pixel; unsigned char tmp; + unsigned long vclk; + debug("enter\n"); hdispend = var->xres / 8 - 1; hsyncstart = (var->xres + var->right_margin) / 8; @@ -1014,11 +1014,11 @@ static int tridentfb_set_par(struct fb_info *info) write3X4(Performance, 0x92); write3X4(PCIReg, 0x07); /* MMIO & PCI read and write burst enable */ - /* convert from picoseconds to MHz */ - par->vclk = 1000000 / info->var.pixclock; + /* convert from picoseconds to kHz */ + vclk = PICOS2KHZ(info->var.pixclock); if (bpp == 32) - par->vclk *= 2; - set_vclk(par->vclk); + vclk *= 2; + set_vclk(vclk); write3C4(0, 3); write3C4(1, 1); /* set char clock 8 dots wide */ |