[Bug 76564] [AMD Fusion E-350] HDMI refresh rates doesn't match expectations

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=76564

--- Comment #21 from Alex Deucher <agd5f at yahoo.com> ---
(In reply to comment #20)
>  
> When I look at the xrandr output I wonder if the reference frequency is not
> 75MHz for fgrlx? Can the reference even change is this not fixed by the
> hardware?

As far as I know, it's fixed.  I'm not really sure what fglrx is doing. 
Anyway, it's probably easier to just fix the open source driver.

the modes are:
  1920x1080 (0x55)  148.5MHz +HSync +VSync *current +preferred
        h: width  1920 start 2448 end 2492 total 2640 skew    0 clock   56.2KHz
        v: height 1080 start 1084 end 1089 total 1125           clock   50.0Hz

  1920x1080 (0x5a)   74.2MHz +HSync +VSync
        h: width  1920 start 2558 end 2602 total 2750 skew    0 clock   27.0KHz
        v: height 1080 start 1084 end 1089 total 1125           clock   24.0Hz

and the driver ends up calculating the dividers as such:

for 148.5MHz target clock:
(100Mhz * 23.8) / (2 * 8) = 148.75Mhz

for 74.2MHz target clock:
(100Mhz * 23.7) / (2 * 16) = 74.0625Mhz

One would need to tweak radeon_compute_pll_avivo() in radeon_display.c to try
and get dividers that are closer to the target clock.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/dri-devel/attachments/20140328/54a1fde8/attachment.html>