[U-Boot] [PATCH 3/8] pxa_lcd: allow L_BIAS line to be unused

Mike Dunn
2013-04-09T17:02:44Z

On 04/07/2013 10:28 PM, Marek Vasut wrote:
> Dear Mike Dunn,
>
>> This patch adds a config option CONFIG_SYS_LCD_PXA_NO_L_BIAS, which causes
>> the lcd controller initialization code to leave as an ordinary gpio the
>> line that is typically configured as the lcd L_BIAS alternate function
>> (this is the gpio 77 line).
>>
>> For some reason (I don't have a datasheet), the lcd device on the
>> palmtreo680 board does not use the L_BIAS line. PalmOS does not configure
>> the gpio 77 line for the L_BIAS alternate function, and if it is
>> configured as such, the lcd does not work.
>>
>> Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
>
> The other option would be to pull the GPIO setup from the driver. That'd be the
> best.

Well, there's a lot of shared code in pxafb_setup_gpio() that handles pin
configuration for all possible interface widths.

But after looking at this problem some more, I realized that the board-specific
lcd_enable() is called after the pxa driver's initialization, so the board code
can undo the L_BIAS pin configuration. Not elegant, but better than the ugly
#ifdefs.

Thanks,
Mike