https://bugs.freedesktop.org/show_bug.cgi?id=48880
--- Comment #13 from Tvrtko Ursulin tvrtko.ursulin@onelan.co.uk 2012-04-19 03:29:24 PDT --- I've added some more debug which goes all the way to just before the ATOM BIOS call.
Without RADEON_PLL_PREFER_MINM_OVER_MAXP:
[ 3.440262] atombios_crtc_set_pll: p1pll [ 3.440265] > atombios_adjust_pll ss_enabled=0 [ 3.440267] atombios_adjust_pll: avivo [ 3.440269] atombios_adjust_pll: 2b [ 3.440273] atombios_adjust_pll: AdjustDisplayPll frev=1, crev=3 [ 3.440276] atombios_adjust_pll: clock=148500 [ 3.440280] - atombios_adjust_pll: adjusted_clock=148500 [ 3.440285] atombios_crtc_set_pll: adjusted_clock=148500, pll_clock=14843, fb_div=95, frac_fb_div=0, ref_div=8, post_div=8 [ 3.440288] atombios_crtc_set_pll: mode->clock=148500, ss_enabled=0 [ 3.440291] atombios_crtc_program_ss: DCE4 [ 3.440296] atombios_crtc_program_pll: frev=1, crev=5 [ 3.440301] atombios_crtc_program_pll: crtc_id=0, clock=148500, ref_div=8, fb_div=95, frac_fb_div=0, post_div=8, bpc=8, pll_id=0, encoder_id=21, encoder_mode=15
Monitor here claims 175.9MHz pixel clock. We have two options here. Either the monitor is lying (for all other tested modes this monitor reports pixel clock correctly though) or an ATOM BIOS bug?
With RADEON_PLL_PREFER_MINM_OVER_MAXP:
[ 3.428121] atombios_crtc_set_pll: p1pll [ 3.428123] > atombios_adjust_pll ss_enabled=0 [ 3.428125] atombios_adjust_pll: avivo [ 3.428127] atombios_adjust_pll: 2b [ 3.428131] atombios_adjust_pll: AdjustDisplayPll frev=1, crev=3 [ 3.428134] atombios_adjust_pll: clock=148500 [ 3.428138] - atombios_adjust_pll: adjusted_clock=148500 [ 3.428143] atombios_crtc_set_pll: adjusted_clock=148500, pll_clock=14857, fb_div=52, frac_fb_div=0, ref_div=7, post_div=5 [ 3.428147] atombios_crtc_set_pll: mode->clock=148500, ss_enabled=0 [ 3.428150] atombios_crtc_program_ss: DCE4 [ 3.428155] atombios_crtc_program_pll: frev=1, crev=5 [ 3.428160] atombios_crtc_program_pll: crtc_id=0, clock=148500, ref_div=7, fb_div=52, frac_fb_div=0, post_div=5, bpc=8, pll_id=0, encoder_id=21, encoder_mode=15
Monitor here correctly reports 148.5MHz pixel clock and displays the signal fine.