Linux boot sequence reset GPIOs modules

samuel ko

Hi,

I have a problem with AM335 Linux 3.2 kernel about GPIO configurations.

In fact, we need to configure GPIO very very quickly at startup. So we choose to do it in u-boot.

But during kernel boot sequence, the kernel reset GPIO1, GPIO2 and GPIO3

CM_PER_GPIO1_CLKCTRL=0x3000 (value at reset)
CM_PER_GPIO2_CLKCTRL=0x3000 (value at reset)
CM_PER_GPIO3_CLKCTRL=0x3000 (value at reset)

The kernel seem to do this reset in function omap_device_enable (file arch/arm/plat-omap/omap_device.c), by calling function

_omap_device_activate.

I try to comments these call, but kernel crash, and no messages appears.

So my questions is how i can avoid GPIO module reset, in order to don't loose u-boot gpio configurations

Thanks by advance,

Best regards,

0 Sekhar Nori over 11 years ago

Hi,

I recently had to keep GPIO0 from resetting across Linux boot and the following patch helped me do that

Can you see if a similar change for other GPIO banks helps you?

Thanks,

Sekhar

0 samuel ko over 11 years ago in reply to Sekhar Nori

Hi,

Can you provide me a solution to not modify GPIO2 and GPIO3?

I work with kernel 3.2 Release 04.06.00.06 ( February 2012), but i use your kernel version in order to test your patch.

In the same way, i found a lot of patchs for am335x kernel, so i would like to know if TI plan to provide a stable version in next weeks ?

If i apply all theses patch, i won't be able to know exactly the version (release) of my kernel.

Thanks by advance,

0 samuel ko over 11 years ago in reply to samuel ko

Sorry, i achieved to modify file omap_hwmod_33xx_data.c in order to avoid GPIOX reset.

Thanks

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