ATI Drivers report bogus dot_clock to xvidtune
eich at suse.de
Wed Mar 29 01:24:53 PST 2006
Alex Deucher writes:
> I also don't see how the dotclock would be of any use for vblank, but
> I suspect you are seeing a limitation of mergedfb. Mergedfb is
> basically a hack to treat 2 crtcs as a single screen. since you have
> two crtcs with different timings there's no way to know which dotclock
> or refresh rate, etc. is relevant (since they both are). Hence you end
> up with some weirdness for certain fields. Disable mergedfb if you
> want relevant numbers for those fields.
I came across a similar problem in randr. It turned out that this really
ugly hack in radeon_mergefb.c:
/* Provide a sophisticated fake DotClock in order to trick the vidmode
* extension to allow selecting among a number of modes whose merged result
* looks identical but consists of different modes for CRT1 and CRT2
mode->Clock = (((i->Clock >> 3) + i->HTotal) << 16) | ((j->Clock >> 2) + j->
mode->Clock ^= ((i->VTotal << 19) | (j->VTotal << 3));
caused the problem.
I'm not sure if anyone but the author knows what it is good for.
It's not unlikely that the problem with xvidtune is also caused by
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