Linux/TDA2P-ACD: PPS signal on GPIO

Suzana Komarcevski

Part Number: TDA2P-ACD

Tool/software: Linux

Hi,

We have custom tda2p board and we connected PPS signal from GPS device to GPIO7_14. We enabled PPS support in kernel and added following changes in dra76-evm.dts file:

pps {
    compatible = "pps-gpio";
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_pps>;
    gpios = <&gpio7 14 GPIO_ACTIVE_HIGH>;
    status = "okay";
};

…

&dra7_pmx_core {
   pinctrl_pps: pinctrl_pps {
       pinctrl_single, pins = <
           0x3c0 (PIN_INPUT_PULLDOWN | MUXMODE14)
       >;
   };
};

However, we don't have any log messages about pps source nor any directory in /sys/class/pps. What are we missing?

Regards,

Suzana

over 5 years ago

0 Yordan Kamenov over 5 years ago

TI__Mastermind 42515 points

Hi Suzana,

I am not expert on this, but shouldn't "pinctrl_single, pins" in your code be "pinctrl-single, pins" (note the dash vs. underscore)?

Regards,
Yordan

0 Suzana Komarcevski over 5 years ago in reply to Yordan Kamenov

Prodigy 145 points

Hi,

Sorry, I made a typo in my previous post. It is "pinctrl-single, pins".

pps {
    compatible = "pps-gpio";
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_pps>;
    gpios = <&gpio7 14 GPIO_ACTIVE_HIGH>;
    status = "okay";
};

…

&dra7_pmx_core {
    pinctrl_pps: pinctrl_pps {
        pinctrl-single,pins = <
            0x3c0 (PIN_INPUT_PULLDOWN | MUX_MODE14)
        >;
    };
};

0 Yordan Kamenov over 5 years ago in reply to Suzana Komarcevski

TI__Mastermind 42515 points

Hi Suzana,

the GPIO experts has been notified and will reply here, but some delay might be expected due to holidays in India.

Regards,
Yordan

0 Nikhil Devshatwar over 5 years ago in reply to Yordan Kamenov

TI__Genius 9905 points

Hi Suzana,

Can you infer something from the kernel log.

I suspect that the gpio7 device tree node may not be enabled. Please confirm if the GPIO7 is being registered to linux.

You can export GPIO7_14 (I guess 216) in the sysfs and read/write the entries there.

echo 216 > /sys/class/gpio/export and see if you can read /sys/class/gpio/gpio216/value

I don't know much about the PPS devices, but try to enable some logs which will give details of the failure.

Regards,

Nikhil D

0 Suzana Komarcevski over 5 years ago in reply to Nikhil Devshatwar

Prodigy 145 points

Hi,

For easier testing I changed gpio. Now I use GPIO4_4. I added coresponding node in dts for pin mux and I changed mux for that pin in mux_data.h in u-boot/board/ti/dra7xx. GPIO4 module is enabled, and I can export GPIO4_4 (which is 100) in sysfs and red/write entries there. So it seems that gpio side is ok but still there is no progress with pps.

Regards,
Suzana

0 Nikhil Devshatwar over 5 years ago in reply to Suzana Komarcevski

TI__Genius 9905 points

Hi Suzana,

This seems to be generic kernel issue where the PPS driver isnt able to use the GPIO.
Did you find any logs from the PPS driver. Where do you see failure in the PPS driver?
Add few breakpoints or prints to infer where does the pps driver getting any failure

TI does not modify anything with respect to the pps driver, neither it is one of the supported feature.
You have already confirmed that the GPIO functionality is working.

Regards,
Nikhil D

0 Suzana Komarcevski over 5 years ago in reply to Nikhil Devshatwar

Prodigy 145 points

Hi,

I don't see any failure in PPS driver. These are only logs from PPS driver:

I also enabled PPS debugging messages in kernel but logs are the same.

Regards,

Suzana

0 Nikhil Devshatwar over 5 years ago in reply to Suzana Komarcevski

TI__Genius 9905 points

Hi,

TI does not support PPS driver.

As you have confirmed, GPIO read/writes are working.

If you feel there is some issue with PPS drivers, ask the kernel community.

Regards,

Nikhil D

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Linux/TDA2P-ACD: PPS signal on GPIO