SOLVED: XF86_SVGA (xfree86 3.3.6) for wd90c24 at 8ppb?

[jony_jrslm]

I have an old IBM Thinkpad 345cs - see http://www.thinkwiki.org/wiki/Category:345CS for general specifications - my model has 20MB RAM (up from the 4MB RAM standard!).

I've loaded potato on it from floppy disks. The problem is setting up a graphics screen with 8ppb. With XF86_VGA16, I can get either a 640x480 or 800x600 graphics screen, but only with 4ppb.

According to the thinkwiki people, I SHOULD be able to get 8ppb for a 640x480 graphics screen using XF86_SVGA. Actually, I DO get a stable screen with 640x480@8ppb, but the image is doubled (shows on the top half and again on the bottom half) and it wraps around the screen (left-right) a bit as well. I suspect that this is because the wd90c24a2 is a DSTN video card (dual-scan super twisted nematic), but have no idea how to deal with the problems.

SOLUTION: Thanks to Michael Steiner!

/* T P D U A L S C A N . C

Author: Michael Steiner
<steiner@acm.org> <sti@zurich.ibm.com>
http://www.zurich.ibm.com/pub/sti/www/info.html

This program allows you to set videoram for dualscan equipped thinkpads
(at least for the 750Cs but probably also for others) to allow running
XFree86 without patching it. (normally you got all twice if the upper 512K
of videoram are not disabled)

JS@JSComputerWorks:
The XF86Config file must contain Videoram 512 in the Device section;
If it does not contain the Videoram option, X automatically "probes"
the card and discovers there's actually 1024 - it undoes what the
tpdualscan program does

Usage:
a) you run on the built-in monitor:
(1) run 'tpdualscan -d' as root
(2) start X (e.g with startx)
b) you run on an external monitor:
(1) run 'tpdualscan -e' as root
(2) start X (e.g with startx)
*/

#define PROGNAME "tpdualscan"

#include <stdio.h>
#include <unistd.h>
#include <errno.h>

/* the prototypes for helper routines (freely adapted from Xfree86 */
static __inline__ void outb(short port, char val);
static __inline__ unsigned int inb(short port);
void EnableIOPorts(int num_ioports, unsigned *io_ports);
void DisableIOPorts(int num_ioports, unsigned *io_ports);


/* define IO ports for vga and pvga (we probably don't need all but why bother ..) */
unsigned PVGA_IOPorts[] = {
/* normal vga ports */
0x3B4, 0x3B5, 0x3BA, 0x3C0, 0x3C1, 0x3C2, 0x3C4, 0x3C5, 0x3C6, 0x3C7,
0x3C8, 0x3C9, 0x3CA, 0x3CB, 0x3CC, 0x3CE, 0x3CF, 0x3D4, 0x3D5, 0x3DA,
/* extra ports for WD90C31 */
0x23C0, 0x23C1, 0x23C2, 0x23C3, 0x23C4, 0x23C5 };
int Num_PVGA_IOPorts = (sizeof(PVGA_IOPorts)/sizeof(PVGA_IOPorts[0]));

char usage[] = "usage: "PROGNAME"(-d(isable) | -e(nable) | -s(tatus))";


int main (int argc, char *argv[]) {
unsigned long vgaIOBase;
int colorEmulation, dualScan;
enum {enable, disable, status} mode = status;
unsigned char registr; /* ugly but register was already taken .. */

/* parse command line */
if ((argc > 2) || ((argc == 2) && (argv[1][0] != '-'))){
fprintf(stderr, "%s\n", usage); exit(1);
}
if (argc == 2) {
switch (argv[1][1]) {
case 'h':
printf("%s\ndisable/enable upper 512K of VRAM for dual-scan thinkpads\n", usage); exit(0);
case 'd': /* disable */
mode = disable; break;
case 'e': /* enable */
mode = enable; break;
case 's': /* status */
mode = status; break;
default:
fprintf(stderr, "invalid option %c\n%s\n", argv[1][1], usage); exit(1);
}
}

/* enable VGA and WD ports */
EnableIOPorts(Num_PVGA_IOPorts, PVGA_IOPorts);

/* set vga IO base depend from color mode */
colorEmulation = inb(0x3CC) & 0x01;
if (!colorEmulation) {
fprintf(stderr, "you are not running a dual scan thinkpad \n");
exit(1);
}
vgaIOBase = (colorEmulation) ? 0x3D0 : 0x3B0;

/* unlock flat panel registers PR18, PR19, PR!a, PR36-PR41 and PR44 */
outb(vgaIOBase + 4, 0x34); /* PR1B */
registr = inb(vgaIOBase + 5);
outb(vgaIOBase + 5, ((registr & 0x1F) | 0xA0)); /* set bits 5-7 to 101 */

/* check if we have a dual-scan LCD */
outb(vgaIOBase + 4, 0x31);
dualScan = ((inb(vgaIOBase + 5) & 0xB) == 0); /* dual scan == (PR18[bit:3,1,0] = 0) */
if (!dualScan) {
fprintf(stderr, "you are not running a dual scan thinkpad \n");
exit(1);
}

/* clear bit 6 to disable upper 512k The remaining 512Kbytes
of video memory are not disabled by clearing the bit, but it
is actually used as a shadow of first 512Kbyte */
outb(0x3CE, 0x0B);
registr = inb(0x3CF); /* PR1 */

if (mode == disable) {
printf("setting vramsize to 512K\n");
outb(0x3CE, 0x0B); outb(0x3CF, registr & 0xBF); /* enable 512 */
} else if (mode == enable) {
printf("setting vramsize to 1024K\n");
outb(0x3CE, 0x0B); outb(0x3CF, registr | 0xC0); /* enable 1024 */
} else {
printf("current vramsize is %dK\n", ( (registr & 0x40) ? 1024 : 512));
}

/* cleanup */
/* lock flat panel registers PR18, PR19, PR!a, PR36-PR41 and PR44 */
outb(vgaIOBase + 4, 0x34); /* PR1B */
registr = inb(vgaIOBase + 5);
outb(vgaIOBase + 5, (registr & 0x1F)); /* set bits 5-7 to other than 101 */

/* enable VGA and WD ports */
DisableIOPorts(Num_PVGA_IOPorts, PVGA_IOPorts);
}

/* helper functions (originaly borrowed from XFree86 but stripped unnecessary stuf) f*/

void EnableIOPorts(int num_ioports, unsigned *io_ports)
{
int i;

if (iopl(3) != 0) { /* for ports > 3FF */
fprintf(stderr, "%s: Failed to raise I/O privileges to 3 (%s)\n",
PROGNAME, strerror(errno));
}

for (i = 0; i < num_ioports; i++)
{
unsigned port = io_ports;

if (port > 0x3FF)
continue;

if (ioperm(port, 1, 1) < 0) {
fprintf(stderr, "%s: Failed to enable I/O port 0x%x (%s)\n",
PROGNAME, port, strerror(errno));
exit(1);
}
}
return;
}

void DisableIOPorts(int num_ioports, unsigned *io_ports)
{
int i;

if (iopl(0) != 0) { /* for ports > 3FF */
fprintf(stderr, "%s: Failed to lower I/O privileges to 0 (%s)\n",
PROGNAME, strerror(errno));
}

for (i = 0; i < num_ioports; i++)
{
unsigned port = io_ports;

if (port > 0x3FF)
continue;

if (ioperm(port, 1, 0) < 0) {
fprintf(stderr, "%s: Failed to disable I/O port 0x%x (%s)\n",
PROGNAME, port, strerror(errno));
}
}
return;
}

static __inline__ void
outb(port, val)
short port;
char val;
{
__asm__ __volatile__("out%B0 (%1)" : :"a" (val), "d" (port));
}

static __inline__ unsigned int
inb(port)
short port;
{
unsigned char ret;
__asm__ __volatile__("in%B0 (%1)" :
"=a" (ret) :
"d" (port));
return ret;
}


This compiles/links with gcc with no problems. I ran it as root by entering ./tpdualscan -d

John C Saunders