Re: [PATCH] matroxfb: another attempt to rectify jitter (G450/G550)

["Paul A. Clarke" <pc@us.ibm.com>]

Ville,

Ville Syrjälä wrote:
> I see. It seems to always use VIDPLL with CRTC2. So if DVICLK is to be 
> used with CRTC2 it apparently needs to be added in the VIDPLL case. 
> Hmmm. I wonder if the code even supports CRTC2+DVI because the CRTC2 
> code seems to leave the C2PIXCLK selection to PCICLK if CRTC2 drives DVI 
> only. Did you try to map CRTC2 to DVI?

So, I just (finally) ran the following tests, on a SLES10 system (2.6.16+) with 
G450, both with and without the patch (results were identical):

- with "video=matroxfb:outputs:012"
                   D-shell               DVI-D
on boot             OK                   junk
X dual fb0/fb1      OK                    OK
X fb0 only         black(!)              junk
X fb1 only        signal problems(!)     OK, but yellow(?)

- with "video=matroxfb:outputs:021"
                   D-shell               DVI-D
on boot            junk                   OK
X dual fb0/fb1      OK                    OK
X fb0 only         junk                   OK
X fb1 only        OK, but yellow        OK (blank)

Note that I ignored the DVI-A output, which is apparently the first "output". 
Earlier testing showed pretty much what I'd expect on that channel.

So, it appears that CRTC2 can indeed drive DVI-D.

It also appears that this area still needs work, but any objections to moving 
the suggested patch into -mm ?  It provides clean signals and removes the 
platform-specific hacked ifdefs.

-- 
Regards,
Paul Clarke

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