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Subject: [PATCH] Intel FB pixel clock calculation fix
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Intel framebuffer mis-calculated pixel clocks.

The pixel clock (and thus both H and V sync) will be slower than requested, so
if you set the minimum allowed the display may not sync.  In case of really
old CRT display it could theoretically damage it.

I'm using it with PAL TV (using RGB input - SCART connector) and the bug
prevented it from working at all (TV requirements are more strict and made the
bug visible).

Signed-off-by: Krzysztof Halasa <khc@pm.waw.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>
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Krzysztof Halasa authored and Linus Torvalds committed Sep 12, 2007
1 parent ba0268a commit 9c54ea9
Showing 1 changed file with 3 additions and 3 deletions.
6 changes: 3 additions & 3 deletions drivers/video/intelfb/intelfbhw.c
Original file line number Diff line number Diff line change
Expand Up @@ -924,10 +924,10 @@ calc_pll_params(int index, int clock, u32 *retm1, u32 *retm2, u32 *retn, u32 *re
if (m > pll->max_m)
m = pll->max_m - 1;
for (testm = m - 1; testm <= m; testm++) {
f_out = calc_vclock3(index, m, n, p);
f_out = calc_vclock3(index, testm, n, p);
if (splitm(index, testm, &m1, &m2)) {
WRN_MSG("cannot split m = %d\n", m);
n++;
WRN_MSG("cannot split m = %d\n",
testm);
continue;
}
if (clock > f_out)
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