https://bugzilla.kernel.org/show_bug.cgi?id=29502 Summary: Change to legacy algo to preferring lower post dividers breaks certain modelines Product: Drivers Version: 2.5 Kernel Version: 2.6.38-rc5 Platform: All OS/Version: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: Video(DRI - non Intel) AssignedTo: drivers_video-dri@xxxxxxxxxxxxxxxxxxxx ReportedBy: bitbytebit@xxxxxxxxx Regression: Yes There's an issue with some legacy chips plus low dotclocks in the 2.6.38-rc5 kernel, This is the change/patch that broke them. Reverting this patch, they work as they did before... "Also, switch the legacy algo back to preferring lower post dividers." @@ -849,7 +951,7 @@ void radeon_compute_pll(struct radeon_pll *pll, max_fractional_feed_div = pll->max_frac_feedback_div; } - for (post_div = max_post_div; post_div >= min_post_div; --post_div) { + for (post_div = min_post_div; post_div <= max_post_div; ++post_div) { uint32_t ref_div; if ((pll->flags & RADEON_PLL_NO_ODD_POST_DIV) && (post_div & 1)) A person has a ATI Radeon 9200SE 5964 (AGP)and with 2.6.38-rc4-git4+ it works while with 2.6.38-rc5 there are certain (not all) modelines with low dotclocks that end up being totally out of sync. Here's an example of a non-working modeline for him with the newer kernel, vs. the older one step back before the patch with the above change... # toki 256x224@xxxxx 15.6774Khz ModeLine "256x224x59.61" 5.518455 256 272 304 352 224 235 238 263 -HSync -VSync There's a lot of other ones thought that can work with the same lower dotclocks, so I'm not sure why that is, he tested that change with the legacy pll computation reversed back to how it was and now works again with modelines like the above. Thanks, Chris -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. ------------------------------------------------------------------------------ The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE: Pinpoint memory and threading errors before they happen. Find and fix more than 250 security defects in the development cycle. Locate bottlenecks in serial and parallel code that limit performance. http://p.sf.net/sfu/intel-dev2devfeb -- _______________________________________________ Dri-devel mailing list Dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
