lcd4linux

picoLCDGraphic: change backlight from bool to byte

Based on patch submitted by Mike Edwards <pf-debian-bugs@mirkwood.net>
to Debian Bug #861993 (https://bugs.debian.org/861993). See excerpt from bug
report below.

-----------------------------------------
Dear Maintainer,

Using driver 'picoLCDGraphic' in lcd4linux.conf, backlight can only be set to 0 or 1 (off/on).
While the backlight of the picolcd is on at boot, the moment lcd4linux starts, the backlight turns
off with either setting.

Looking at the source for the driver, I found that somewhere along the line, the function to
set the backlight had been changed to use an 8 bit value from 0 - 255, effectively making this
a brightness setting:

static int drv_pLG_backlight(int backlight)
{
    unsigned char cmd[2] = { 0x91 };    /* set backlight */

    if (backlight < 0)
        backlight = 0;
    if (backlight > 255)
        backlight = 255;

    cmd[1] = backlight;
    drv_pLG_send(cmd, 2);

    return backlight;
}

... but the config option for backlight was still limited to only accepting a 0 or 1:
    if (cfg_number(section, "Backlight", 0, 0, 1, &value) > 0) {
        info("Setting backlight to %d", value);
        drv_pLG_backlight(value);
    }

I've patched that if statement above to accept values between 0 and 255.  Now, setting the config
option for backlight to 255 in lcd4linux.conf does result in the backlight being turned on at
full brightness.
-----------------------------------------

Signed-off-by: Jonathan McCrohan <jmccrohan@gmail.com>

git-svn-id: https://ssl.bulix.org/svn/lcd4linux/trunk@1204 3ae390bd-cb1e-0410-b409-cd5a39f66f1f