This is a slight hardware change on the HMI Board which now uses GPIO14 for enabling the backlight. The current version of the DB500SYS Board still uses PIO0 for this.
Without backlight you won't see anything on a TFT as you remarked correctly. With the changes attached to this message the backlight should be switched on and tux should appear on the framebuffer in the standard configuration. Depending on the build steps you are using it may be neccessary to edit the diff's in the "kernel-patches-target" directory of your project. (netx_nxeb500-bsp.diff and netx_nxdb500-bsp.diff)
:!: :!: CAUTION:
The following lines may only be used for the NXEB500HMI Board. This setting may damage the netX on other Boards which have GPIO14 connected directly to ground!!! :!: :!:
File: arch/arm/mach-netx/nxeb500hmi.c
Function: nxeb500hmi_clcd_setup
writel(3, NETX_SYSTEM_IOC_CR);val = readl(NETX_PIO_OUTPIO);
writel(val | 1, NETX_PIO_OUTPIO);
to
writel(3, NETX_SYSTEM_IOC_CR);/* GPIO 14 is used for display enable on newer boards */
writel(9, NETX_GPIO_CFG(14));val = readl(NETX_PIO_OUTPIO);
writel(val | 1, NETX_PIO_OUTPIO);
PS: There's also an issue with colors blue and red being twisted. This should be changed in nxeb500hmi.c and nxdb500sys.c
Files: arch/arm/mach-netx/nxeb500hmi.c, arch/arm/mach-netx/nxdb500.c
Change in structure qvga
.cntl = CNTL_LCDTFT,
to
.cntl = CNTL_LCDTFT | CNTL_BGR,
PPS: All these issues will be fixed in the next BSP release, which will also include a touch screen driver based on tslib.