[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: NPaul A. Clarke <pc@us.ibm.com>
Signed-off-by: NIan Romanick <idr@us.ibm.com>
Signed-off-by: NPetr Vandrovec <petr@vandrovec.name>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

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 {

drivers/video/matrox/matroxfb_DAC1064.h

@@ -40,6 +40,7 @@ void DAC1064_global_restore(WPMINFO2);
 #define M1064_XCURCOL1RED	0x0C
 #define M1064_XCURCOL1GREEN	0x0D
 #define M1064_XCURCOL1BLUE	0x0E
+#define M1064_XDVICLKCTRL	0x0F
 #define M1064_XCURCOL2RED	0x10
 #define M1064_XCURCOL2GREEN	0x11
 #define M1064_XCURCOL2BLUE	0x12
@@ -144,6 +145,7 @@ void DAC1064_global_restore(WPMINFO2);
 #define M1064_XVIDPLLN		0x8F
 
 #define M1064_XPWRCTRL		0xA0
+#define     M1064_XPWRCTRL_PANELPDN	0x04
 
 #define M1064_XPANMODE		0xA2
 

drivers/video/matrox/matroxfb_base.h

@@ -672,6 +672,8 @@ void matroxfb_unregister_driver(struct matroxfb_driver* drv);
 
 #define M_SEQ_INDEX	0x1FC4
 #define M_SEQ_DATA	0x1FC5
+#define     M_SEQ1		0x01
+#define        M_SEQ1_SCROFF		0x20
 
 #define M_MISC_REG_READ	0x1FCC