radeon: Regression between v3.6-rc4 and v3.6-rc6: unable to allocate a PPLL

[Deucher, Alexander]

> -----Original Message-----
> From: Andres Freund [mailto:andres at anarazel.de]
> Sent: Monday, September 17, 2012 7:29 AM
> To: LKML; Deucher, Alexander; David Airlie; dri-devel at lists.freedesktop.org
> Subject: radeon: Regression between v3.6-rc4 and v3.6-rc6: unable to
> allocate a PPLL
> 
> Hi,
> 
> While debugging another issue I upgraded from v3.6-rc4 to latest git (which
> exactly is v3.6-rc6). After X started up one of my three monitors blacked out.
> A look into the kernel log revealed:
> [drm:radeon_atom_pick_pll] *ERROR* unable to allocate a PPLL


What 3 monitors are you using (DVI, HDMI, DP, VGA)? Note that there are only 2 PLLs for non-DP monitors, so if you are trying to use more than 2 non-DP monitors, it's not supported right now and if it worked before, it was random luck.  If you want to use 3+ monitors, only 2 can be non-DP, the rest need to be DP.  If you use a DP to DVI/HDMI adapter, it must be active (looks like DP to the GPU), passive adapters just pass through native DVI/HDMI.  That said, I've got a set of patches for 3.7 to allow PLL sharing properly for non-DP displays, but it's too invasive for -fixes.

Alex