How to use gpio_set_var() to control gp1[13] of DM8168 in kernel 2.6.37?

I use RDK reference board.  I use the kernel in rdk 01.01.00.04. I want to set alarm 1 ouput 1 or 0. In schematic, this is gp1[12]. But when I use gpio_set_value(12 + 32, 0/1), the gpio do not do the action.

Besides, I enabled gpio sysfs. Use gpio sysfs also can not triggle the gp1[12]. I want to know:

(1) The gp1[x] is not (32 + x) in kernel driver?

(2) Before I use [root@/sys/kernel/debug]# ls
asoc      bdi       clock     gpio      kprobes   memblock  musb      omap_mux  regdump   testmode  usb       vram
[root@/sys/kernel/debug]# cat gpio
GPIOs 0-31, gpio:
 gpio-0   (vgpio 0             ) in  lo
 gpio-1   (vgpio 1             ) in  lo
 gpio-2   (vgpio 2             ) in  lo
 gpio-3   (vgpio 3             ) in  lo
 gpio-16  (eeprom sd0          ) out lo
 gpio-17  (eeprom sdi          ) in  lo
 gpio-18  (eeprom clk          ) out hi
 gpio-19  (eeprom cs           ) out lo

gpio_direction_output(num, 1);

gpio_set_value(num, val);

What should  I check firstly? Thanks.

GPIOs 32-63, gpio:
 gpio-44  (sysfs               ) out lo
[root@/sys/kernel/debug]# echo 1>/sys/class/gpio/gpio44/value
[root@/sys/kernel/debug]# cat gpio
GPIOs 0-31, gpio:
 gpio-0   (vgpio 0             ) in  lo
 gpio-1   (vgpio 1             ) in  lo
 gpio-2   (vgpio 2             ) in  lo
 gpio-3   (vgpio 3             ) in  lo
 gpio-16  (eeprom sd0          ) out lo
 gpio-17  (eeprom sdi          ) in  lo
 gpio-18  (eeprom clk          ) out hi
 gpio-19  (eeprom cs           ) out lo

GPIOs 32-63, gpio:
 gpio-44  (sysfs               ) out lo
[root@/sys/kernel/debug]#

Hi Yaming Deng,

Could you please follow this post

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/p/130602/486897.aspx

Regards

Anilkumar

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The problem is the kernel gpio api gpio_free() .

gpio_free()

  |

  \----- omap_gpio_free()

        |

        \----- _reset_gpio() ==> this will set gpio as input. That maybe the root cause.

So, If you want to set the gpio output, during the period,  you can not  call gpio_free(). I think it is reasonable for power sensitive product such as consumptive electronicy.

But others, it maybe not good for use.

Hi Yaming Deng,

While setting the gpio output, why are you touching gpio_free()?

Regards

Anilkumar

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Hi Anilkumar,

We add a char driver of gpio for our product restore button, led, alarm in, alarm out and soon on.

We use kernel gpio lib api.

(1) gpio_request();

(2) gpio_directxx()

(3) gpio_set/get_value()

(4) gpio_free()

 That is why I touch the gpio_free(). Do you think gpio_free() should change the last status of gpio? Do you have a better idea? Thanks.

Yaming

Hi Yaming,

These are the steps you have to follow for GPIO to functional in expected behaviour.

1. gpio_request(<gpio_number>, "label_name")

Ex: gpio_request(20, "test_gpio");

2. Write some thing to gpio pin

gpio_direction_output(<gpio_number>, 0 or 1);

 Ex: gpio_direction_output(20, 0);

3. Read data from gpio pin

value = gpio_get_value(<gpio_number>);

Ex: value = gpio_get_value(20);

4. Once you done with your operation then call

gpio_free(<gpio_number>);

Ex: gpio_free(20);

In your case you should not call gpio_free() API. If you do above steps sequentially then "set value become default value after 4th step".

Regards

Anilkumar

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