cirrusfb: fix clock doubling
Cirrus' Alpine and Picasso4 chips uses DAC clock doubling to achieve full range of pixclock frequencies. [akpm@linux-foundation.org: fix spelling, use usual comment layout] 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>
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@ -470,10 +470,25 @@ static int cirrusfb_check_pixclock(const struct fb_var_screeninfo *var,
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/* If the frequency is greater than we can support, we might be able
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/* If the frequency is greater than we can support, we might be able
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* to use multiplexing for the video mode */
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* to use multiplexing for the video mode */
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if (freq > maxclock) {
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if (freq > maxclock) {
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dev_err(info->device,
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"Frequency greater than maxclock (%ld kHz)\n",
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maxclock);
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return -EINVAL;
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}
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/*
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* Additional constraint: 8bpp uses DAC clock doubling to allow maximum
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* pixel clock
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*/
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if (var->bits_per_pixel == 8) {
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switch (cinfo->btype) {
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switch (cinfo->btype) {
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case BT_ALPINE:
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case BT_ALPINE:
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case BT_PICASSO4:
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if (freq > 85500)
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cinfo->multiplexing = 1;
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break;
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case BT_GD5480:
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case BT_GD5480:
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cinfo->multiplexing = 1;
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if (freq > 135100)
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cinfo->multiplexing = 1;
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break;
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break;
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default:
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default:
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@ -815,6 +830,8 @@ static int cirrusfb_set_par_foo(struct fb_info *info)
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freq = PICOS2KHZ(var->pixclock);
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freq = PICOS2KHZ(var->pixclock);
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if (cinfo->btype == BT_ALPINE && var->bits_per_pixel == 24)
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if (cinfo->btype == BT_ALPINE && var->bits_per_pixel == 24)
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freq *= 3;
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freq *= 3;
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if (cinfo->multiplexing)
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freq /= 2;
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bestclock(freq, &nom, &den, &div);
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bestclock(freq, &nom, &den, &div);
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