Description of problem: When using the radeon driver, modelines with dotclocks of less than 20 Mhz are ignored. Using a tweaked driver (from the .src.rpm) which ignores this limitation, the card uses modelines with lower dotclocks without any hassles. Version-Release number of selected component (if applicable): XFree86-4.2.1-10.2 How reproducible: Always Steps to Reproduce: 1. Put a modeline with a dotclock < 20 Mhz into XF86Config, use it Actual results: Modeline gets ignored due to too low dotclock (according to /var/log/XFree86.*.log) Expected results: Modeline gets used or (if the card is lying about its capabilities) a configuration option should exist which overrides the limitd determined by XFree86.
Sample modeline to reproduce?
Modeline "720x576" 13.875 720 744 808 888 576 582 588 625 -hsync -vsync interlace # H 15625 [Hz], V 50 [Hz] That's 720x576 PAL, let me know if you want an NTSC one -- I have some NTSC modelines, but they're not tested.
Created attachment 89971 [details] Patch that ensures a minimum dotclock of >= 12.5 Mhz Do not use this at home kids. It might break your VGA card, your monitor or even more. Seriously: This patch forces the driver to use a minimum dotlock of 12.5 Mhz (or less). I don't know if there are any Radeons that can't handle that (mine does) and how they would react in that case. This should preferably be a configuration option ('Option "EnsureTVDotClocks" "yes"'? -- we might have to ensure that the max dotclock is at minimum 17.5 Mhz -- yeah right :o)), but I don't know how to implement such options and I'm currently to busy/lazy to figure out.
This type of thing would be a feature enhancement, and not really a bug fix. Due to the potentially hardware-damaging nature of such a change, I won't consider something like this for our current development. It's IMHO something that should be requested upstream in order to be given wider coverage. Setting to DEFERRED
Created attachment 95161 [details] Patch implementing an option to force a specific minimum dotclock on Radeon cards This patch implements the "ForceMinDotclockenstein" option in the Radeon driver. It accepts a frequency as its argument (like in "12.5Mhz"). This patch documents the option in the radeon man page.
Created attachment 95511 [details] Patch implementing an option to force a specific minimum dotclock on Radeon cards Revised patch as suggested by Kevin Martin: - rename option to "ForceMinDotClock" - fix code duplication
File this patch upstream, deferred.
Fixed in xorg-x11-6.7.0-0.5.