vga: softscreen

allow the shadow framebuffer (softscreen) to be used with any
vga driver, not just vesa. this removes the ugly scr->paddr = 0
hack employed by vesa driver to force softscreen and adds a
softscreen vgactl message that can switch the feature on and off
at runtime.

softscreen can greatly improve graphics performance when bus
reads are slow even tho it disables hardware acceleration.

sys/man/3/vga

@@ -170,6 +170,22 @@ used by the graphics engine.
 The default setting is
 .BR on .
 .TP
+.BI softscreen " mode"
+Depending on whether
+.I mode
+is 
+.B on
+or
+.BR off ,
+enable or disable shadow framebuffer to reduce
+slow bus reads. Enabling
+.BI softscreen
+disables hardware acceleration. The default setting is
+.BR off
+except for the
+.BR vesa
+driver. 
+.TP
 .BI hwblank " mode"
 Depending on whether
 .I mode

sys/man/8/plan9.ini

@@ -781,10 +781,6 @@ and
 .BR off .
 The first two specify differing levels of power saving;
 the third turns the monitor off completely.
-.SS \fL*novesashadow=\fP
-This disables the shadow framebuffer or softscreen of the VESA
-video driver. This can improve performance on some graphics
-cards.
 .SS NVRAM
 .SS \fLnvram=\fIfile\fP
 .SS \fLnvrlen=\fIlength\fP

sys/src/9/pc/devvga.c

@@ -46,6 +46,7 @@ enum {
 	CMtextmode,
 	CMtype,
 	CMunblank,
+	CMsoftscreen,
 };
 
 static Cmdtab vgactlmsg[] = {
@@ -63,6 +64,7 @@ static Cmdtab vgactlmsg[] = {
 	CMtextmode,	"textmode",	1,
 	CMtype,		"type",		2,
 	CMunblank,	"unblank",	1,
+	CMsoftscreen,	"softscreen",	2,
 };
 
 static void
@@ -200,6 +202,7 @@ vgaread(Chan* c, void* a, long n, vlong off)
 		len += snprint(p+len, READSTR-len, "hwblank %s\n", hwblank ? "on" : "off");
 		len += snprint(p+len, READSTR-len, "panning %s\n", panning ? "on" : "off");
 		len += snprint(p+len, READSTR-len, "addr p 0x%lux v 0x%p size 0x%ux\n", scr->paddr, scr->vaddr, scr->apsize);
+		len += snprint(p+len, READSTR-len, "softscreen %s\n", scr->softscreen ? "on" : "off");
 		USED(len);
 
 		n = readstr(offset, a, n, p);
@@ -352,13 +355,31 @@ vgactl(Cmdbuf *cb)
 		scr->palettedepth = x;
 		return;
 
+	case CMsoftscreen:
+		if(strcmp(cb->f[1], "on") == 0)
+			scr->softscreen = 1;
+		else if(strcmp(cb->f[1], "off") == 0)
+			scr->softscreen = 0;
+		else
+			break;
+		if(scr->gscreen == nil)
+			return;
+		x = scr->gscreen->r.max.x;
+		y = scr->gscreen->r.max.y;
+		z = scr->gscreen->depth;
+		chan = scr->gscreen->chan;
+		cursoroff(1);
+		deletescreenimage();
+		if(screensize(x, y, z, chan))
+			error(Egreg);
+		/* no break */
 	case CMdrawinit:
 		if(scr->gscreen == nil)
 			error("drawinit: no gscreen");
 		if(scr->dev && scr->dev->drawinit)
 			scr->dev->drawinit(scr);
 		hwblank = scr->blank != nil;
-		hwaccel = scr->scroll || scr->fill;
+		hwaccel = !scr->softscreen && (scr->scroll || scr->fill);
 		vgascreenwin(scr);
 		resetscreenimage();
 		cursoron(1);

sys/src/9/pc/screen.c

@@ -67,17 +67,21 @@ screensize(int x, int y, int, ulong chan)
 	}
 
 	if(scr->paddr == 0){
-		gscreen = allocmemimage(Rect(0,0,x,y), chan);
 		if(scr->dev && scr->dev->page){
 			scr->vaddr = KADDR(VGAMEM());
 			scr->apsize = 1<<16;
 		}
+		scr->softscreen = 1;
+	}
+	if(scr->softscreen){
+		gscreen = allocmemimage(Rect(0,0,x,y), chan);
 		scr->useflush = 1;
 	}else{
 		static Memdata md;
 
 		md.ref = 1;
-		md.bdata = scr->vaddr;
+		if((md.bdata = scr->vaddr) == 0)
+			error("framebuffer not maped");
 		gscreen = allocmemimaged(Rect(0,0,x,y), chan, &md);
 		scr->useflush = scr->dev && scr->dev->flush;
 	}
@@ -167,15 +171,12 @@ attachscreen(Rectangle* r, ulong* chan, int* d, int* width, int *softscreen)
 	return scr->gscreendata->bdata;
 }
 
-/*
- * It would be fair to say that this doesn't work for >8-bit screens.
- */
 void
 flushmemscreen(Rectangle r)
 {
 	VGAscr *scr;
 	uchar *sp, *disp, *sdisp, *edisp;
-	int y, len, incs, off, page;
+	int y, len, incs, off, xoff, page;
 
 	scr = &vgascreen[0];
 	if(scr->gscreen == nil || scr->useflush == 0)
@@ -184,13 +185,37 @@ flushmemscreen(Rectangle r)
 		scr->dev->flush(scr, r);
 		return;
 	}
-	if(scr->dev == nil || scr->dev->page == nil)
-		return;
-
 	if(rectclip(&r, scr->gscreen->r) == 0)
 		return;
-
+	disp = scr->vaddr;
 	incs = scr->gscreen->width * BY2WD;
+	xoff = (r.min.x*scr->gscreen->depth) / 8;
+	off = r.min.y*incs + xoff;
+	sp = scr->gscreendata->bdata + scr->gscreen->zero + off;
+
+	/*
+	 * Linear framebuffer but with softscreen.
+	 */
+	if(scr->paddr){
+		len = (r.max.x*scr->gscreen->depth + 7) / 8;
+		len -= xoff;
+		sdisp = disp + off;
+		edisp = sdisp + Dy(r)*incs;
+		while(sdisp < edisp){
+			memmove(sdisp, sp, len);
+			sdisp += incs;
+			sp += incs;
+		}
+		return;
+	}
+
+
+	/*
+	 * Paged access thru 64K window.
+	 * It would be fair to say that this doesn't work for >8-bit screens.
+	 */
+	if(scr->dev == nil || scr->dev->page == nil)
+		return;
 
 	switch(scr->gscreen->depth){
 	default:
@@ -202,18 +227,11 @@ flushmemscreen(Rectangle r)
 	}
 	if(len < 1)
 		return;
-
-	off = r.min.y*scr->gscreen->width*BY2WD+(r.min.x*scr->gscreen->depth)/8;
 	page = off/scr->apsize;
 	off %= scr->apsize;
-	disp = scr->vaddr;
 	sdisp = disp+off;
 	edisp = disp+scr->apsize;
 
-	off = r.min.y*scr->gscreen->width*BY2WD+(r.min.x*scr->gscreen->depth)/8;
-
-	sp = scr->gscreendata->bdata + off;
-
 	scr->dev->page(scr, page);
 	for(y = r.min.y; y < r.max.y; y++) {
 		if(sdisp + incs < edisp) {
@@ -740,4 +758,3 @@ VGAcur swcursor =
 	swload,
 	swmove,
 };
-

sys/src/9/pc/screen.h

@@ -120,6 +120,7 @@ struct VGAscr {
 	ulong	id;	/* internal identifier for driver use */
 	int isblank;
 	int overlayinit;
+	int softscreen;
 };
 
 extern VGAscr vgascreen[];

sys/src/9/pc/vganvidia.c

@@ -69,7 +69,7 @@ enum {
 
 #define SKIPS 8
 
-struct {
+static struct {
 	ulong	*dmabase;
 	int	dmacurrent;
 	int	dmaput;
@@ -90,11 +90,6 @@ nvidiapci(void)
 	return nil;
 }
 
-static void
-nvidialinear(VGAscr*, int, int)
-{
-}
-
 static void
 nvidiaenable(VGAscr* scr)
 {
@@ -114,11 +109,9 @@ nvidiaenable(VGAscr* scr)
 	if(scr->mmio == nil)
 		return;
 	addvgaseg("nvidiammio", p->mem[0].bar&~0x0F, p->mem[0].size);
-
 	vgalinearpci(scr);
 	if(scr->apsize)
 		addvgaseg("nvidiascreen", scr->paddr, scr->apsize);
-
 	/* find video memory size */
 	switch (scr->id & 0x0ff0) {
 	case 0x0020:
@@ -155,6 +148,11 @@ nvidiaenable(VGAscr* scr)
 	}
 }
 
+static void
+nvidialinear(VGAscr *, int, int)
+{
+}
+
 static void
 nvidiacurdisable(VGAscr* scr)
 {
@@ -223,8 +221,6 @@ nvidiacurload(VGAscr* scr, Cursor* curs)
 
 	scr->offset = curs->offset;
 	vgaxo(Crtx, 0x31, vgaxi(Crtx, 0x31) | 0x01);
-
-	return;
 }
 
 static int
@@ -355,12 +351,15 @@ waitforidle(VGAscr *scr)
 		iprint("idle stat %lud scrio %#p scr %#p pc %#p\n", *pgraph, scr->mmio, scr, getcallerpc(&scr));
 }
 
-static void
+static int
 nvresetgraphics(VGAscr *scr)
 {
 	ulong	surfaceFormat, patternFormat, rectFormat, lineFormat;
 	int	pitch, i;
 
+	if(scr->paddr == 0)
+		return -1;
+
 	pitch = scr->gscreen->width*BY2WD;
 
 	/*
@@ -373,10 +372,8 @@ nvresetgraphics(VGAscr *scr)
 		else{
 			nv.dmabase = (void*)vmap(scr->paddr + scr->storage - 128*1024, 128*1024);
 			if(nv.dmabase == 0){
-				hwaccel = 0;
-				hwblank = 0;
 				print("vmap nvidia dma failed\n");
-				return;
+				return -1;
 			}
 		}
 	}
@@ -455,6 +452,8 @@ nvresetgraphics(VGAscr *scr)
 
 	nvdmakickoff(scr);
 	waitforidle(scr);
+
+	return 0;
 }
 
 
@@ -513,9 +512,9 @@ nvidiablank(VGAscr*, int blank)
 static void
 nvidiadrawinit(VGAscr *scr)
 {
-	nvresetgraphics(scr);
 	scr->blank = nvidiablank;
-	hwblank = 1;
+	if(nvresetgraphics(scr) < 0)
+		return;
 	scr->fill = nvidiahwfill;
 	scr->scroll = nvidiahwscroll;
 }

sys/src/9/pc/vgavesa.c

@@ -24,7 +24,6 @@ enum {
 	RealModeBuf = 0x9000,
 };
 
-static void *hardscreen;
 static uchar modebuf[0x1000];
 static Chan *creg, *cmem;
 static QLock vesaq;
@@ -108,12 +107,6 @@ vesalinear(VGAscr *scr, int, int)
 	Pcidev *pci;
 	uchar *p;
 
-	if(hardscreen) {
-		scr->vaddr = hardscreen;
-		scr->paddr = scr->apsize = 0;
-		return;
-	}
-
 	vbecheck();
 	mode = vbegetmode();
 	/*
@@ -163,38 +156,8 @@ vesalinear(VGAscr *scr, int, int)
 	vgalinearaddr(scr, paddr, size);
 	if(scr->apsize)
 		addvgaseg("vesascreen", scr->paddr, scr->apsize);
-	if(getconf("*novesashadow"))
-		return;
-	hardscreen = scr->vaddr;
-	scr->paddr = scr->apsize = 0;
-}
 
-static void
-vesaflush(VGAscr *scr, Rectangle r)
-{
-	int t, w, wid, off;
-	ulong *hp, *sp, *esp;
-
-	if(hardscreen == nil)
-		return;
-	if(rectclip(&r, scr->gscreen->r) == 0)
-		return;
-	sp = (ulong*)(scr->gscreendata->bdata + scr->gscreen->zero);
-	t = (r.max.x * scr->gscreen->depth + 2*BI2WD-1) / BI2WD;
-	w = (r.min.x * scr->gscreen->depth) / BI2WD;
-	w = (t - w) * BY2WD;
-	wid = scr->gscreen->width;
-	off = r.min.y * wid + (r.min.x * scr->gscreen->depth) / BI2WD;
-
-	hp = hardscreen;
-	hp += off;
-	sp += off;
-	esp = sp + Dy(r) * wid;
-	while(sp < esp){
-		memmove(hp, sp, w);
-		hp += wid;
-		sp += wid;
-	}
+	scr->softscreen = 1;
 }
 
 static int
@@ -285,8 +248,4 @@ VGAdev vgavesadev = {
 	0,
 	vesalinear,
 	vesadrawinit,
-	0,
-	0,
-	0,
-	vesaflush,
 };