kernel startup - why does it change gpio value ?

ranchu

Guru 20755 points

Other Parts Discussed in Thread: SYSCONFIG

Hello,

I observe the following strange behaviour:

On linux startup it changes a gpio value which was set in u-boot.

I've tried to debug where this change of value comes from, and I don't yet know the exact place where this happens,

but I validated that this happens before the call to: ti8148_evm_init() routine.

So it must be very early in the startup. I am not sure yet where. It seems as if it disbales all gpios or that it is a matter of power domain issue ?

Linux is compiled with OMAP_MUX disabled (all pinmux is done in u-boot).

I work on dm8148.

Is there any idea why and where kernel change value of gpio ?

Regards,

Ran

over 9 years ago

0 Titusrathinaraj Stalin over 9 years ago

TI__Guru** 116100 points

Dear Ran,
Can you please try to do the same in different GPIO and check whether you are getting the same effect in that GPIO too ?

0 ranchu over 9 years ago in reply to Titusrathinaraj Stalin

Guru 20755 points

Hi Titus,

I have found an answer with the help of e2e search...
e2e.ti.com/.../291377
It is a matter of removing
SYSC_HAS_SOFTRESET attribute:

static struct omap_hwmod_class_sysconfig ti81xx_gpio_sysc = {
.sysc_offs = 0x0010,
.syss_offs = 0x0114,
.sysc_flags = (SYSC_HAS_AUTOIDLE | SYSC_HAS_ENAWAKEUP |
- SYSC_HAS_SIDLEMODE | SYSC_HAS_SOFTRESET |
+ SYSC_HAS_SIDLEMODE /*| SYSC_HAS_SOFTRESET*/ |
SYSS_HAS_RESET_STATUS),
.idlemodes = (SIDLE_FORCE | SIDLE_NO | SIDLE_SMART |
SIDLE_SMART_WKUP),

Though I am still curious what else affected from this change, I see that reboot is still avialbale.

Thanks,
Ran

0 Titusrathinaraj Stalin over 9 years ago in reply to ranchu

TI__Guru** 116100 points

Sounds good.

Thanks for your update.

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kernel startup - why does it change gpio value ?