[PATCH] matroxfb: fix DVI setup to be more compatible

There has been a longstanding problem with the Matrox G450 and perhaps
other similar cards, with modes "above" 1280x1024-60 on ppc/ppc64 boxes
running Linux.  Higher resolutions and/or higher refresh rates resulted in
a very noticably "jittery" display, and sometimes no display, depending on
the physical monitor.  This patch fixes that problem on the systems I have
easy access to...

I've tested with SLES9SP3 (2.6.5+ kernel) and 2.6.16-rc6 custom kernels on
an IBM eServer p5 520 w/G450 (a.k.a GXT135P on IBM's ppc64 systems), and a
colleague of mine (Ian Romanick) tested it successfully on an Apple ppc32
box (w/GXT135P).  I also tested it on IA32 box I have with a GXT135P to
verify that it didn't obviously break anything.  In my testing, I covered
single-card, single and dual-head setups using both HD15 and DVI-D signals,
on both the IA32 and ppc64 boxes.  While everything appeared fine on both
boxes, I did encounter one problem: I can't get any signal on the DVI-D
output on the ppc64 box.  However, this is also the case without my patch.

I just noticed that screen-blanking only occurs on the primary display as
well.

Signed-off-by: Paul A. Clarke <pc@us.ibm.com>
Signed-off-by: Ian Romanick <idr@us.ibm.com>
Signed-off-by: Petr Vandrovec <petr@vandrovec.name>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 21 insertions, 2 deletions

diff --git a/drivers/video/matrox/g450_pll.c b/drivers/video/matrox/g450_pll.c
index 8073a73f6f35..440272ad10e7 100644
--- a/drivers/video/matrox/g450_pll.c
+++ b/drivers/video/matrox/g450_pll.c
@@ -316,14 +316,24 @@ static int __g450_setclk(WPMINFO unsigned int fout, unsigned int pll,
                 case M_PIXEL_PLL_B:
                 case M_PIXEL_PLL_C:
                         {
-                                u_int8_t tmp;
+                                u_int8_t tmp, xpwrctrl;
                                 unsigned long flags;
                                 
                                 matroxfb_DAC_lock_irqsave(flags);
+
+                                xpwrctrl = matroxfb_DAC_in(PMINFO M1064_XPWRCTRL);
+                                matroxfb_DAC_out(PMINFO M1064_XPWRCTRL, xpwrctrl & ~M1064_XPWRCTRL_PANELPDN);
+                                mga_outb(M_SEQ_INDEX, M_SEQ1);
+                                mga_outb(M_SEQ_DATA, mga_inb(M_SEQ_DATA) | M_SEQ1_SCROFF);
                                 tmp = matroxfb_DAC_in(PMINFO M1064_XPIXCLKCTRL);
+                                tmp |= M1064_XPIXCLKCTRL_DIS;
                                 if (!(tmp & M1064_XPIXCLKCTRL_PLL_UP)) {
-                                        matroxfb_DAC_out(PMINFO M1064_XPIXCLKCTRL, tmp | M1064_XPIXCLKCTRL_PLL_UP);
+                                        tmp |= M1064_XPIXCLKCTRL_PLL_UP;
                                 }
+                                matroxfb_DAC_out(PMINFO M1064_XPIXCLKCTRL, tmp);
+                                matroxfb_DAC_out(PMINFO M1064_XDVICLKCTRL, 0);
+                                matroxfb_DAC_out(PMINFO M1064_XPWRCTRL, xpwrctrl);
+
                                 matroxfb_DAC_unlock_irqrestore(flags);
                         }
                         {
@@ -418,6 +428,15 @@ static int __g450_setclk(WPMINFO unsigned int fout, unsigned int pll,
                                    frequency to higher - with <= lowest wins, while
                                    with < highest one wins */
                                 if (delta <= deltaarray[idx-1]) {
+                                        /* all else being equal except VCO,
+                                         * choose VCO not near (within 1/16th or so) VCOmin
+                                         * (freqs near VCOmin aren't as stable)
+                                         */
+                                        if (delta == deltaarray[idx-1]
+                                            && vco != g450_mnp2vco(PMINFO mnparray[idx-1])
+                                            && vco < (pi->vcomin * 17 / 16)) {
+                                                break;
+                                        }
                                         mnparray[idx] = mnparray[idx-1];
                                         deltaarray[idx] = deltaarray[idx-1];
                                 } else {