atom feed3 messages in com.googlegroups.beagleboard[beagleboard] Re: GPIO conflict with ...
FromSent OnAttachments
Chao YouMar 15, 2010 11:06 pm 
UlrichMar 29, 2010 7:50 am 
UlrichMar 31, 2010 7:40 am 
Subject:[beagleboard] Re: GPIO conflict with kernel root?
From:Ulrich (ulri@gmail.com)
Date:Mar 29, 2010 7:50:24 am
List:com.googlegroups.beagleboard

Hi Chao,

On Mar 16, 7:07 am, Chao You <chao@ndsu.edu> wrote:

CONFIG_OMAP_MUX has to be enable. But when the CONFIG_OMAP_MUX is enabled, my kernel won't find the root file system anymore. Error message is shown at the bottom.

It seems that the code around MMC detection/write protect is not implemented well. If you comment out the line //omap_cfg_reg(AH8_34XX_GPIO29); in arch/arm/mach-omap2/board-omap3beagle.c it will work again. My u- boot configures this pin to mode3, whereas kernel reconfigures it to mode4(gpio29) when CONFIG_OMAP_MUX is enabled. I am kind of unsure what the exact meaning of this pin is on beagle board. Schematic and description of beagleboard contradict each other.

Another question is related to the mux.c file. The gpio-168 is AF15. The default mux.c file is set to MODE0. Without enable the OMAP_MUX, if I change mux.c to MODE4, will that enable the gpio-168?

Without enable CONFIG_OMAP_MUX nothing will happen, even if you have it enabled that won't change anything unless you do the proper omap_cfg_reg() call. Please be aware that the mux.c and the enum in arch/arm/plat-omap/ include/mach/mux.h must correspond when adding/removing settings. This is kind of error prone.