[jornada] Jornada 720: saving power, switching off the light

Hello,

I managed to boot Linux on my Jornada 720. (Thanks to everyone for
all those helpful web pages and mailing list contributions!:-) There
is only one problem left that prevents me from really using it:

I do not get power management running. I cannot even turn off the
screen backlight. Running fully powered on battery, the Jornada
"only" survives 6.5 hours which is not enough for outdoor work.
(Also, not being able to turn the light off makes no good
impression.;-)

So far I managed to force the Jornada's screen into "power save
mode" with a small kernel hack (see below). But when coming up
again, the screen looked somewhat unhealthy and needed a long time
to recover, so I took it out again. And anyway, the backlight was
still on.

Any ideas how to enable power management or at least to turn the
backlight off?

Thanks in advance,

    Peter

--- linux-2.4.18-rmk2-hh2-jornada720/drivers/video/epson1356fb.c Thu Mar 21 17:34:08 2002
+++ drivers/video/epson1356fb.c Thu May 30 22:31:36 2002
@@ -188,8 +188,10 @@
  */
 static void e1356fb_blank(int blank, struct fb_info *info)
 {
-int i;
-printk("e1356fb_blank: blank=%d info->modename=%s\n", blank, info->modename);
+#if 0
+ int i;
+ unsigned char *pRegs = REGISTER_OFFSET;
+ printk("e1356fb_blank: blank=%d info->modename=%s\n", blank, info->modename);
         switch (blank) {
         case VESA_POWERDOWN:
         case VESA_VSYNC_SUSPEND:
@@ -197,13 +199,22 @@
                 /* turn light off */
                 jornada_contrast(0);
                 jornada_brightness(0);
+ /* Disable the display. */
+ pRegs[0x1FC] = 0;
+ /* Turn on power save mode. */
+ pRegs[0x1F0] = 1;
                 break;
         case VESA_NO_BLANKING:
+ /* Turn off power save mode. */
+ pRegs[0x1F0] = 0;
+ /* Enable the display. */
+ pRegs[0x1FC] = 1;
                 /* turn light on */
                 i = jornada_brightness(8);
-printk("brightness %x\n", i);
+ printk("brightness %x\n", i);
                 jornada_contrast(current_contrast);
         }
+#endif
 }
 
 static int
Received on Sat Jun 01 2002 - 22:51:46 EDT