[Bug 48880] Set mode has different timings than requested on VGA

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=48880

--- Comment #13 from Tvrtko Ursulin <tvrtko.ursulin at 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.

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