Xv and resolution loss on matrox cards

[Michael Lampe]

I'm rehashing an old thread from xpert, 
http://marc.theaimsgroup.com/?t=97722090500003&r=1&w=2 and propose the 
following patch, derived from how mga_vid.c (kernel module for Matrox 
BES from mplayer) programs the card. It basically disables that 
'accelerated 2x horizontal zoom' thing which causes the problem. (With 
this option on, it looks like information from only every other pixel is 
used.)

It also turns back on 'chroma upsampling' (which was only turned off in 
a failed attempt to solve the issue, see quoted thread) and changes the 
vsync position to 2 (a la mga_vid.c, seems as good a constant as what 
was used before but is simpler).

A good example for testing is 
http://cox.iwr.uni-heidelberg.de/~ug/films/stefan.mov

-Michael

Index: programs/Xserver/hw/xfree86/drivers/mga/mga_video.c
===================================================================
RCS file: /cvs/xc/programs/Xserver/hw/xfree86/drivers/mga/mga_video.c,v
retrieving revision 1.34
diff -u -r1.34 mga_video.c
--- programs/Xserver/hw/xfree86/drivers/mga/mga_video.c 20 Feb 2004 16:59:49 -0000     
 1.34
+++ programs/Xserver/hw/xfree86/drivers/mga/mga_video.c 15 Apr 2004 12:35:35 -0000
@@ -578,48 +578,29 @@
     short src_w, short src_h,
     short drw_w, short drw_h
 ){
+#define VSYNC_POS 2
+
     MGAPtr pMga = MGAPTR(pScrn);
-    int tmp, hzoom, intrep;
-    int maxOverlayClock;
+    int tmp, intrep;
 
     CHECK_DMA_QUIESCENT(pMga, pScrn);
 
-    /* got 48 scanlines to do it in */
-    tmp = INREG(MGAREG_VCOUNT) + 48;
-    /* FIXME always change it in vertical retrace use CrtcV ?*/
-    if(tmp > pScrn->currentMode->CrtcVTotal)
-       tmp -= 49; /* too bad */
-    else
-        tmp = pScrn->currentMode->CrtcVTotal -1;
-
-    tmp = pScrn->currentMode->VDisplay +1;
-    /* enable accelerated 2x horizontal zoom when pixelclock >135MHz */
-
-    if ((pMga->ChipRev >= 0x80) || (pMga->Chipset == PCI_CHIP_MGAG550)) {
-       /* G450, G550 */
-       maxOverlayClock = 234000;
-    } else {
-       maxOverlayClock = 135000;
-    }
-
-    hzoom = (pScrn->currentMode->Clock > maxOverlayClock) ? 1 : 0;
-
     switch(id) {
     case FOURCC_UYVY:
-       OUTREG(MGAREG_BESGLOBCTL, 0x000000c0 | (3 * hzoom) | (tmp << 16));
+       OUTREG(MGAREG_BESGLOBCTL, 0x000000c0 | (VSYNC_POS << 16));
        break;
     case FOURCC_YUY2:
     default:
-       OUTREG(MGAREG_BESGLOBCTL, 0x00000080 | (3 * hzoom) | (tmp << 16));
+       OUTREG(MGAREG_BESGLOBCTL, 0x00000080 | (VSYNC_POS << 16));
        break;
     }
 
     OUTREG(MGAREG_BESA1ORG, offset);
 
     if(y1 & 0x00010000)
-       OUTREG(MGAREG_BESCTL, 0x00040c41);
+       OUTREG(MGAREG_BESCTL, 0x00050c41);
     else 
-       OUTREG(MGAREG_BESCTL, 0x00040c01);
+       OUTREG(MGAREG_BESCTL, 0x00050c01);
  
     OUTREG(MGAREG_BESHCOORD, (dstBox->x1 << 16) | (dstBox->x2 - 1));
     OUTREG(MGAREG_BESVCOORD, (dstBox->y1 << 16) | (dstBox->y2 - 1));
@@ -640,7 +621,7 @@
     OUTREG(MGAREG_BESVISCAL, tmp & 0x001ffffc);
 
     intrep = ((drw_w == src_w) || (drw_w < 2)) ? 0 : 1;
-    tmp = (((src_w - intrep) << 16)/(drw_w - intrep)) << hzoom;
+    tmp = (((src_w - intrep) << 16)/(drw_w - intrep));
     if(tmp >= (32 << 16))
        tmp = (32 << 16) - 1;
     OUTREG(MGAREG_BESHISCAL, tmp & 0x001ffffc);