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

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Message-ID: <A3397C8B8B789E45844E7EC5DEAD89D02C4333B6@sausexdag03.amd.com>
Date:	Mon, 17 Sep 2012 14:24:08 +0000
From:	"Deucher, Alexander" <Alexander.Deucher@....com>
To:	Andres Freund <andres@...razel.de>
CC:	LKML <linux-kernel@...r.kernel.org>,
	David Airlie <airlied@...ux.ie>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: RE: radeon: Regression between v3.6-rc4 and v3.6-rc6: unable to
 allocate a PPLL

> -----Original Message-----
> From: Andres Freund [mailto:andres@...razel.de]
> Sent: Monday, September 17, 2012 9:56 AM
> To: Deucher, Alexander
> Cc: LKML; David Airlie; dri-devel@...ts.freedesktop.org
> Subject: Re: radeon: Regression between v3.6-rc4 and v3.6-rc6: unable to
> allocate a PPLL
> 
> On Monday, September 17, 2012 03:16:56 PM Deucher, Alexander wrote:
> > > -----Original Message-----
> > > From: Andres Freund [mailto:andres@...razel.de]
> > > Sent: Monday, September 17, 2012 7:29 AM
> > > To: LKML; Deucher, Alexander; David Airlie;
> > > dri-devel@...ts.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.
> 2DVI, 1DP via an supposedly active converter. I can try a native DP cable, its
> just too short, so I will have to move the monitor to the ground ;)
> 
> Can I check its really an active connector?

Try the attached debugging patch.  It will tell us what PPLLs are getting allocated and what type of sink we detect on the DP port (DP or non-DP)

> 
> The patchset you referenced is in alexdeucher/drm-next-3.7-wip if I saw that
> correctly? Will test it with a passive connector I have lying arround.
> 

Yes.  Note that PLLs can only be shared for non-DP monitors if the clocks are the same.

Alex


Download attachment "debug_dp.diff" of type "application/octet-stream" (1228 bytes)