[Lcd4linux-devel] picoLCD 256x64 polling very slow

[Martin Z. <co...@mz...>]

Hi!

Today I have finally received my LCD, a picoLCD 256x64.  I was pretty 
impressed how easy the switch from the X11 driver to the actual LCD was 
-- kudos to all of you!  Everthing works fine, however polling the 
buttons using LCD::GPI(1) considerable slows down output on the LCD.  I 
had a look at "drv_picoLCDGraphic.c" and the problem seems to lie in the 
function "drv_pLG_read()".

   static int drv_pLG_read(unsigned char *data, int size)
   {
       return usb_interrupt_read(lcd, USB_ENDPOINT_IN + 1, (char *) data,
           size, 1000);
   }

When I change the timeout value from 1000 to 25 or so, keypress data are 
still received, but there is no notable delay from polling.  If however 
I change timeout to 10000, there is a delay of ten seconds, leading me 
to the suspicion that the polling times out in every single calls of 
"usb_interrupt_read()".  Is this a bug or actually a feature? ;)

Here's what I get when I start lcd4linux with "-Fvv" (skipping the 
config file dump):

   [config file dump]

   plugin_cfg.c: Variable n = '0' (0)
   lcd4linux.c: initializing driver picoLCDGraphic
   picoLCDGraphic: $Rev: 1068 $
   PICOLCD Graphic initialization

   Setting display inverted to 0
   picoLCDGraphic: scanning for picoLCD 256x64...
   picoLCDGraphic: found picoLCD on bus 003 device 003
   picoLCDGraphic: interface 0 already claimed by 'usbhid'
   picoLCDGraphic: attempting to detach driver...
   picoLCDGraphic: Manufacturer='ITUNER INC' Product='USB-LCD-256x64'
     SerialNumber='Ver.00.03'
   drv_picoLCDGraphic.c: drv_pLG_start(): allocated 

   drv_picoLCDGraphic.c: drv_pLG_start(): zeroed 

   Setting contrast to 230
   Setting backlight to 1
   In drv_pLG_clear

   picoLCDGraphic: using 1 GPI's and 8 GPO's
   initializing layout 'picoLCD'

   [and now the usual stuff of entering main loop and so forth]

If anybody has got this LCD, I'll attach my config file.  It basically 
prints "uptime()" and the keypress state on a couple of lines.

I'll be off for a couple of days, so take your time... :)

Thanks,

Martin
-- 
www.mzuther.de
www.radix-musik.de