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vgavesa: get rid of the vesa kproc

in 9front, screen blanking is always initiated from process context,
so there is no need for a kproc anymore.

care has been taken for the race between vesadisable() and vesablank()
by acquiering the drawlock prior calling scr->dev->enable() and
scr->dev->disable(). this also has the side effect of accelerated
fills and scrolls not being called during device disable.

--- a/sys/src/9/pc/devvga.c

+++ b/sys/src/9/pc/devvga.c

@@ -309,6 +309,11 @@

 		for(i = 0; vgadev[i]; i++){

 			if(strcmp(cb->f[1], vgadev[i]->name))

 				continue;

+			qlock(&drawlock);

+			if(waserror()){

+				qunlock(&drawlock);

+				nexterror();

+			}

 			if(scr->dev){

 				if(scr->dev->disable)

 					scr->dev->disable(scr);

@@ -319,6 +324,8 @@

 			scr->dev = vgadev[i];

 			if(scr->dev->enable)

 				scr->dev->enable(scr);

+			qunlock(&drawlock);

+			poperror();

 			return;

 		}

 		break;

--- a/sys/src/9/pc/vgavesa.c

+++ b/sys/src/9/pc/vgavesa.c

@@ -20,18 +20,11 @@

 #include "screen.h"

 enum {

-	Cdisable = 0,

-	Cenable,

-	Cblank,

-

 	RealModeBuf = 0x9000,

 };

 static uchar modebuf[0x1000];

 static Chan *creg, *cmem;

-static QLock vesaq;

-static Rendez vesar;

-static int vesactl;

 #define WORD(p) ((p)[0] | ((p)[1]<<8))

 #define LONG(p) ((p)[0] | ((p)[1]<<8) | ((p)[2]<<16) | ((p)[3]<<24))

@@ -165,59 +158,9 @@

 	scr->softscreen = 1;

 }

-static int

-gotctl(void *arg)

-{

-	return vesactl != *((int*)arg);

-}

-

 static void

-vesaproc(void*)

-{

-	Ureg386 u;

-	int ctl;

-

-	ctl = Cenable;

-	while(ctl != Cdisable){

-		if(!waserror()){

-			sleep(&vesar, gotctl, &ctl);

-			ctl = vesactl;

-

-			vbesetup(&u, 0x4f10);

-			if(ctl == Cblank)

-				u.bx = 0x0101;

-			else	

-				u.bx = 0x0001;

-

-			/*

-			 * dont wait forever here. some BIOS get stuck

-			 * in i/o poll loop after blank/unblank for some

-			 * reason. (Thinkpad A22p)

-			 */

-			procalarm(10000);

-			vbecall(&u);

-

-			poperror();

-		}

-		procalarm(0);

-		up->notepending = 0;

-	}

-	cclose(cmem);

-	cclose(creg);

-	cmem = creg = nil;

-	qunlock(&vesaq);

-

-	pexit("", 1);

-}

-

-static void

 vesaenable(VGAscr *)

 {

-	eqlock(&vesaq);

-	if(waserror()){

-		qunlock(&vesaq);

-		nexterror();

-	}

 	cmem = namec("/dev/realmodemem", Aopen, ORDWR, 0);

 	if(waserror()){

 		cclose(cmem);

@@ -226,29 +169,42 @@

 	}

 	creg = namec("/dev/realmode", Aopen, ORDWR, 0);

 	poperror();

-	poperror();

-

-	vesactl = Cenable;

-	kproc("vesa", vesaproc, nil);

 }

 static void

 vesadisable(VGAscr *)

 {

-	vesactl = Cdisable;

-	wakeup(&vesar);

-

-	/* wait for vesaproc to finish */

-	qlock(&vesaq);

-	qunlock(&vesaq);

+	if(cmem != nil)

+		cclose(cmem);

+	if(creg != nil)

+		cclose(creg);

+	cmem = creg = nil;

 }

 static void

 vesablank(VGAscr *, int blank)

 {

-	if(vesactl != Cdisable){

-		vesactl = blank ? Cblank : Cenable;

-		wakeup(&vesar);

+	Ureg386 u;

+

+	vbesetup(&u, 0x4f10);

+	u.bx = blank ? 0x0101 : 0x0001;

+

+	/*

+	 * dont wait forever when called from mouse kproc.

+	 * some BIOS get stuck in i/o poll loop after

+	 * blank/unblank for some reason. (Thinkpad A22p)

+	 */

+	if(up->kp)

+		procalarm(10000);

+

+	if(!waserror()){

+		vbecall(&u);

+		poperror();

+	}

+

+	if(up->kp){

+		procalarm(0);

+		up->notepending = 0;

 	}

 }