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ubb-vga.c (mode_db): cleanup and added approximations of standard modes

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This commit is contained in:
Werner Almesberger 2011-05-01 23:00:35 -03:00
parent 9412c9debe
commit b184fbbe74
1 changed files with 42 additions and 27 deletions
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69
ubb-vga/ubb-vga.c
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@ -51,41 +51,56 @@ static int bad;
static const struct mode mode_db[] = {
/* name xres yres clkdiv vfront hsync hback htotal */
/* vsync vback */
{ "640x480", 640, 480, 11, 2, 32, 14, US(3.47), US(0.79), US(29.7) },
{ "800x600", 800, 600, 8, 2, 32, 14, US(4.81), US(0.79), US(28.7) },
/* the next one may work after adjusting the timing in "frame" */
{ "800x600", 800, 600, 8, 2, 32, 14, US(4.51), US(0.79), US(28.2) },
{ "640x480/58", 640, 480, 12, 2, 10, 33, US(3.81), US(1.91), US(32.5) },
{ "640x480/70", 640, 480, 9, 2, 8, 29, US(1.90), US(2.06), US(27.5) },
{ "800x600/54", 800, 600, 8, 2, 32, 14, US(4.81), US(0.79), US(28.7) },
{ "800x600/56", 800, 600, 8, 2, 1, 22, US(2.00), US(3.56), US(28.5) },
{ "800x600/72", 800, 600, 5, 3, 1, 27, US(2.14), US(2.70), US(22.0) },
/* the 1024x768 below is not great but has good parameter tolerance */
{ "1024x768", 1024, 768, 8, 2, 32, 14, US(4.51), US(0.79), US(36.0) },
/* illustrate underruns */
/* illustrate underruns (without DMA) */
{ "1024x768ur", 1024, 768, 7, 2, 32, 14, US(2.21), US(0.79), US(33.5) },
{ "1024x768/53",1024, 768, 5, 2, 32, 14, US(1.31), US(0.79), US(23.1) },
{ "1024x768/50",1024, 768, 5, 6, 3, 29, US(2.10), US(2.46), US(24.5) },
{ NULL }
};
/*
* Adjustment value tests with the XEN-1510 (640x480):
*
* Adjustment Tries Good Jam FIFO jitter
* Quick load
* -0.0 10 3 7 0 n
* -0.1 10 5 5 0 n
* -0.2 10 6 4 0 n
* -0.3 10 7 3 0 n
* 10 5 5 0 y
* -0.4 10 1 0 9 n
* 10 5 0 5 n repeat
* 10 5 0 5 y
* -0.5 10 3 0 7 n
* 10 7 0 3 y
* -1.0 5 0 5 0
*
* Good = image is stable
* Jam = does not detect the signal properly, loss of HSYNC, artefacts,
* or no image at all
* FIFO jitter = some lines get shifted by a "digital" amount
*/
/*
* 640x480/58: http://tinyvga.com/vga-timing/640x480@60Hz
*
* H: 3.81+0.64+25.42+1.91 us = 31.78 us
*
* Pixel clock is 25.175 MHz. We have 25.85 MHz, thus:
* 25.42/25.75*25.175 = 24.85
*
* htotal should be 31.77+(24.85-25.175) = 31.445, but we actually need more.
* Seems that our hfront is about 1.7 us.
*
* Observation: bad FIFO jitter.
*
*
* 640x480/70: http://tinyvga.com/vga-timing/640x480@73Hz
*
* That's a pretty ugly adaptation. The DMA really seems to dislike the 73 Hz
* parameters.
*
*
* 800x600/54: just a lucky combination
*
*
* 800x600/56: http://tinyvga.com/vga-timing/800x600@56Hz
*
* Note that we have the sync pulses upside-down.
*
*
* 800x600/7: yet another lucky combination
*
*
* 1024x768/50: loosely based on http://tinyvga.com/vga-timing/1024x768@60Hz
*/
const struct mode *mode = mode_db;