[lcd4linux] bugreport on HD44780 driver for 0.10.0

[Johan S. <Joh...@xs...>]

Hello,

I have a hd44780 which worked very well yesterday evening and stopped 
working this morning. Yesterday evening I used the options -Fvvq when 
testing, today I only remembered the -Fvv part. I found that indeed the 
splashscreen is the troublemaker. Unformatunately I do not understand why.

Here are the details:

processor AMD 1400 Mhz Athlon
kernel    2.4.31
version   lcd4linux-0.10.0
driver    HD44780
size      20x4

part of the verbose output
HD44780: using ppdev /dev/parport0
HD44780: wiring: [DISPLAY:RS]<==>[PARPORT:AUTOFD (Pin 14)]
HD44780: wiring: [DISPLAY:RW]<==>[PARPORT:GND]
HD44780: wiring: [DISPLAY:ENABLE]<==>[PARPORT:STROBE (Pin 1)]
HD44780: wiring: [DISPLAY:ENABLE2]<==>[PARPORT:GND]
HD44780: wiring: [DISPLAY:ENABLE3]<==>[PARPORT:GND]
HD44780: wiring: [DISPLAY:ENABLE4]<==>[PARPORT:GND]
HD44780: wiring: [DISPLAY:BACKLIGHT]<==>[PARPORT:GND]
HD44780: wiring: [DISPLAY:GPO]<==>[PARPORT:GND]
HD44780: not using busy-flag checking


mode 1
Not using splash screen, everything works as it should.


mode 2
Using a splash screen with patched drv_HD44780.c

--- lcd4linux-0.10.0/drv_HD44780.c      2005-06-09 19:41:47.000000000 +0200
+++ /home/johan/work/lcd4linux-0.10.0/drv_HD44780.c  2005-08-09 
15:04:47.0000000
00 +0200
@@ -1489,7 +1489,7 @@

      /* say goodbye... */
      if (!quiet) {
-       drv_generic_text_greet("goodbye!", NULL);
+       drv_generic_text_greet("goodbye", NULL);
      }

      drv_HD_stop();

Indeed, I only removed the exclamation mark in the final splash screen. 
Everything works as it should. ["goodbye! dude" also worked, it seems the
exclamation mark is the cullprit]


mode 3
With the splash screen, starting lcd4linux is ok; stopping lcd4linux is 
ok; restarting results in a messed up display:
- the display only shows line 1 and line 3. Line 1 also shows content of 
line 2 and 4. The initial splash screen now looks like:


      2 4 6 8 0 2 4 6 8 0
    +--------------------+
  1 |orgCD4Linux 0.10.0 *|
  2 |                    |
  3 |    HD44780 20x4    |
  4 |                    |
    +--------------------+

- the contrast has changed such that the background of line 1 and 3 are 
      nearly black. The contrast can be changed by the potmeter I 
connected to my LCD-display.
But this does not give me line 2 and 4.


The final splash screen from mode 2 (that is with my "patch") manages to 
recover the display from being messed up.


I know my patch only solved a symptom. The real problem (why can't I 
show an exclamation mark) is still there. I hope one of the developpers 
is able to find this real problem.


Regards, Johan Swenker