I set GPIO22 as output in a8's app, but the register value is no changed!

yue gu1

ipnc rdk3.8.0 8148

I set GPIO22 as output in uboot 0x48140A9C's value can changed ok.

but I set GPIO22 as output in a8's app, but the register value is no changed!

my a8's app code :

unsigned int uval, addr;
129
130
131     //read ad18 reg
132     addr =0x48140A9C;
133     uval = RD_MEM_32( addr );
134     printf( "0x48140a9c-r---direct:%08x\n", uval);
135
136     //write ad18 to gpio
137     //uval |= 0x00000080;
138     uval = 0x00070082;
139     WR_MEM_32(addr, uval);
140
141     //read writed value
142     uval = RD_MEM_32( addr );
143     printf( "0x48140a9c-w---direct:%08x\n", uval);

the result:

0x48140a9c-r---direct:00050002
0x48140a9c-w---direct:00050002

look forwards for your answer!

why 0x48140A9C 's value no change?

over 10 years ago

0 Pavel Botev over 10 years ago

TI__Guru**** 170625 points

Hi Yue,

yue gu1 said:
but I set GPIO22 as output in a8's app, but the register value is no changed!

Are you able to change the value in 0x48140A9C from user space with devmem2 tool?

root@evm:~# devmem2

Usage:   devmem2 { address } [ type [ data ] ]
   address : memory address to act upon
   type    : access operation type : [b]yte, [h]alfword, [w]ord
   data    : data to be written

root@evm:~# devmem2 0x48140A9C w <your_new_value> --> write the new value

root@evm:~# devmem2 0x48140A9C -------> check if the new value has been applied

Regards,
Pavel

0 yue gu1 over 10 years ago in reply to Pavel Botev

Intellectual 865 points

hi Pavel: devmem2 can not change the value too.

why cann't change it?

root@DM8127_IPNC:~# devmem2 0x48140a9c
/dev/mem opened.
Memory mapped at address 0x401fc000.
Read at address 0x48140A9C (0x401fca9c): 0x00050002
root@DM8127_IPNC:~# devmem2 0x48140a9c w 0x00060080
/dev/mem opened.
Memory mapped at address 0x4024c000.
Read at address 0x48140A9C (0x4024ca9c): 0x00050002
Write at address 0x48140A9C (0x4024ca9c): 0x00060080, readback 0x00060080
root@DM8127_IPNC:~# devmem2 0x48140a9c
/dev/mem opened.
Memory mapped at address 0x40095000.
Read at address 0x48140A9C (0x40095a9c): 0x00050002

0 Pavel Botev over 10 years ago in reply to yue gu1

TI__Guru**** 170625 points

Yue,

May be this pin is used by driver and can not be changed on the fly from user space. Have you tried to change that with sysfs entries? Details in the below wiki page:

processors.wiki.ti.com/.../TI81XX_PSP_GPIO_Driver_User_Guide

Note: GPIO's which are used already in the drivers can not be control from sysfs, unless until driver export that particular pin.

Regards,
Pavel

0 yue gu1 over 10 years ago in reply to Pavel Botev

Intellectual 865 points

I tried to change that with sysfs , it can not work too.

0 Pavel Botev over 10 years ago in reply to yue gu1

TI__Guru**** 170625 points

Yue,

You can change the pinmux from the linux kernel, see if the below approach will be useful for you:

processors.wiki.ti.com/.../TI81XX_PSP_User_Guide

Regards,
Pavel

0 yue gu1 over 10 years ago in reply to Pavel Botev

Intellectual 865 points

I have changed the pinmux in the linux kernel and uboot , all is ok!

but in the app failed!!!

0 yue gu1 over 10 years ago in reply to yue gu1

Intellectual 865 points

hi Pavel :

this seems pin's register is locked in linux app?

in linux app I use same code can not change 0x48140a9c , but can changed 0x48032134 .

0 yue gu1 over 10 years ago in reply to Pavel Botev

Intellectual 865 points

this seems pin's register is locked in linux app?

in linux app I use same code can not change 0x48140a9c , but can changed 0x48032134 .

0 Pavel Botev over 10 years ago in reply to yue gu1

TI__Guru**** 170625 points

Yue,

yue gu1 said:
I have changed the pinmux in the linux kernel and uboot , all is ok!

but in the app failed!!!

Do you mean that when change 0x48140A9C/PINCNTL168 = 0x00060080 in linux kernel, then boot this kernel, you still see the value of 0x00050002 (instead of 0x00060080) in the 0x48140A9C/PINCNTL168 register from user space (checked with devmem2 tool)???

BR
Pavel

0 Pavel Botev over 10 years ago in reply to yue gu1

TI__Guru**** 170625 points

Yue,

yue gu1 said:
his seems pin's register is locked in linux app?

in linux app I use same code can not change 0x48140a9c , but can changed 0x48032134 .

DM814x TRM section 3.2 CONTROL_MODULE Registers states:

All these registers can only be modified by SUPERVISR mode access.

Which means all Control Module registers (from 0x4814_0000 to x4816_0FFF) can be modified/write by supervisor/privileged mode only. In user space we are in user mode, while supervisor/privileged mode we have in u-boot and linux kernel. Thus you should modify these registers only under u-boot/linux kernel. There is no option to modify these registers from user space (with devmem2 tool or with other method).

Just note that when you modify this register in linux kernel, be careful this register to be NOT overwritten from the linux kernel code afterwards.

Regards,
Pavel

0 Pavel Botev over 10 years ago in reply to Pavel Botev

TI__Guru**** 170625 points

See also the below e2e threads:

e2e.ti.com/.../1053217

e2e.ti.com/.../225767

Regards,
Pavel

0 yue gu1 over 10 years ago in reply to Pavel Botev

Intellectual 865 points

hi Pavel:

your mean is I can not modify 0x4814_0000 to x4816_0FFF in user space, I just can modify it in uboot and kernal ?

0 Pavel Botev over 10 years ago in reply to yue gu1

TI__Guru**** 170625 points

Yue,

yue gu1 said:
your mean is I can not modify 0x4814_0000 to x4816_0FFF in user space, I just can modify it in uboot and kernal ?

This is exactly what I mean. Unless you are able to create a gateway in to the Kernel to allow you to access to the protected memory (which seems to be a hard task).

Regards,
Pavel

0 yue gu1 over 10 years ago in reply to Pavel Botev

Intellectual 865 points

Pavel:
I have chaned it on c674. I send msg to c674 then change it on c674. it seems to be ok.

I don't know wether it is reasonable ? why can change it on c674?

0 Pavel Botev over 10 years ago in reply to yue gu1

TI__Guru**** 170625 points

By default, the C674x DSP is in supervisor mode. If you do not change to user mode, you will remain in supervisor mode. Thus you are able to modify the register content.

You can look at the TMS320C674x DSP CPU and Instuction Set Reference Guide (SPRUFE8B) “Section 8: CPU Privilege” to understand better about the CPU privileges and methods to Enter Supervisor mode from User mode and vice versa.

www.ti.com/.../sprufe8b.pdf

Regards,
Pavel

0 yue gu1 over 10 years ago in reply to Pavel Botev

Intellectual 865 points

thanks a lot for your help!!

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I set GPIO22 as output in a8's app, but the register value is no changed!