i.MX Processors中的主题 Re: Re: Problems modifying device tree to blink an LED

Problems modifying device tree to blink an LED

rathben — Wed, 05 Feb 2014 20:15:47 GMT

Hello All -

I've had a surprising amount of difficulty trying to figure out how to use dts to configure the hardware to heartbeat-blink the debug led on the i.MX6SL EVK. I'm running kernel 3.10.17, building core-image-minimal, and tried adding the following code in the appropriate places in imx6sl-evk.dts (as well as enabling the appropriate items in the kernel menuconfig):

leds {

compatible = "gpio-leds";

debug-led {

label = "Heartbeat";

gpios = <&gpio3 20 0>; //HSIC_STROBE -> GPIO3_20

linux,default-trigger = "heartbeat";

};

and

MX6SL_PAD_HSIC_STROBE__GPIO3_IO20 0x110b0

After much trial and error, I was able to get this to work after modifying the init function register_init_complete (in .../git/drivers/regulator/core.c) to return early without doing anything.

I'm looking into this further, but in the meantime, does anyone have any ideas about what is going on here?

Thanks! -Ben

Re: Problems modifying device tree to blink an LED

fabio_estevam — Thu, 06 Feb 2014 00:27:48 GMT

It should be

MX6SL_PAD_HSIC_STROBE__GPIO3_IO20 0x80000000

Regards,

Fabio Estevam

Re: Problems modifying device tree to blink an LED

rathben — Thu, 06 Feb 2014 02:50:04 GMT

Hi Fabio, thanks for your response. Please clarify. What is the significance of this value? The 31st bit isn't defined by any documentation I've seen. I will double-check tomorrow but I believe I did try this value before going on my frantic adventure commenting out initialization functions out until it worked.

Re: Problems modifying device tree to blink an LED

fabio_estevam — Thu, 06 Feb 2014 02:57:40 GMT

It is documented at:

http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/Documentation/devicetree/bindings/pinctrl/fsl,imx-pinctrl.txt?h=imx_3.10.17_1.0.0_beta

"Bits used for CONFIG: NO_PAD_CTL(1 << 31): indicate this pin does not need config."

So the LED still does not work?

Regards,

Fabio Estevam

Re: Problems modifying device tree to blink an LED

rathben — Thu, 06 Feb 2014 04:44:44 GMT

thank you for the documentation link, I'll try it tomorrow when I get back to the hardware. Thanks!

Re: Problems modifying device tree to blink an LED

MarekVasut — Thu, 06 Feb 2014 05:06:41 GMT

That NO_PAD_CTL means 'don't touch the current configuration of the pin, it was configured by bootloader', right ?

Re: Problems modifying device tree to blink an LED

MarekVasut — Thu, 06 Feb 2014 05:13:07 GMT

Check if you have the necessary stuff enabled in your kernel config ...

$ grep LED_TRIGGERS .config

$ grep LEDS_TRIGGER_HEARTBEAT .config

$ grep LEDS_GPIO .config

Next, check if your pin is really configured as GPIO. I don't see

pinctrl-names = "default";

pinctrl-0 = <&led_pin_gpio>;

anywhere in your led {} DT node. You should have those two right under the 'compatible' prop AND the led_pin_gpio should be defined in the &iomuxc node like so:

                led_pin_gpio: led_gpio@0 {

                        fsl,pins = <

                                MX6SL_PAD_HSIC_STROBE__GPIO3_IO20            0x110b0

                        >;

                };

You can use /sys/class/leds/*/brightness to toggle the led when debugging this stuff.

Re: Problems modifying device tree to blink an LED

fabio_estevam — Thu, 06 Feb 2014 14:14:41 GMT

Ben,

I have just tested with this changes and it works here:

--- a/arch/arm/boot/dts/imx6sl-evk.dts

+++ b/arch/arm/boot/dts/imx6sl-evk.dts

@@ -19,6 +19,18 @@

reg = <0x80000000 0x40000000>;

};

+ leds {

+ compatible = "gpio-leds";

+ pinctrl-names = "default";

+ pinctrl-0 = <&pinctrl_led>;

+ user {

+ label = "Heartbeat";

+ gpios = <&gpio3 20 0>;

+ linux,default-trigger = "heartbeat";

+ };

regulators {

compatible = "simple-bus";

#address-cells = <1>;

@@ -108,6 +120,12 @@

};

+ pinctrl_led: ledgrp {

+ fsl,pins = <

+ MX6SL_PAD_HSIC_STROBE__GPIO3_IO20 0x17059

+ >;

+ };

pinctrl_kpp: kppgrp {

fsl,pins = <

MX6SL_PAD_KEY_ROW0__KEY_ROW0 0x1b010

Regards,

Fabio Estevam

Re: Problems modifying device tree to blink an LED

fabio_estevam — Thu, 06 Feb 2014 14:56:07 GMT

Some more hints:

Stop the heartbeat blinking:

$ echo none > /sys/class/leds/Heartbeat/trigger

Turn on the LED:

$ echo 1 > /sys/class/leds/Heartbeat/brightness

Turn off the LED:

$ echo 0 > /sys/class/leds/Heartbeat/brightness

Regards,

Fabio Estevam

Re: Problems modifying device tree to blink an LED

rathben — Thu, 06 Feb 2014 17:38:25 GMT

changing the pad config to 0x80000000 did not get the led to work. I will go on to trying the other suggestions below

Re: Problems modifying device tree to blink an LED

rathben — Thu, 06 Feb 2014 18:23:39 GMT

this is helpful but doesn't work for me. I can see that during bootup the led blinks once and then stops around the time that regulator_init_complete runs

Re: Problems modifying device tree to blink an LED

rathben — Thu, 06 Feb 2014 18:33:25 GMT

same result as with Marek's suggestions. Side note, is there a significance to you placing the pinctrl_led node in regulators while Marek suggested iomuxc? Also I noticed that your patch is not based from the same version of imx6sl-evk.dts as mine. Is there something else in the file that I might be missing?

Re: Problems modifying device tree to blink an LED

fabio_estevam — Thu, 06 Feb 2014 19:31:06 GMT

I haven't put the pinctrl_led node into regulators. The patch I sent is against 3.14-rc1. Haven't tested 3.10 yet.

Regards,

Fabio Estevam

Re: Re: Problems modifying device tree to blink an LED

rathben — Thu, 06 Feb 2014 19:58:22 GMT

ok. I've placed pinctrl_led in the &iomuxc node as follows, is this correct? (still doesn't work, but at least we'll be on the same page)

&iomuxc {

pinctrl-names = "default", "sleep";

pinctrl-0 = <&pinctrl_hog>;

pinctrl-1 = <&pinctrl_hog_sleep>;

pinctrl_led: ledgrp {

fsl,pins = <

MX6SL_PAD_HSIC_STROBE__GPIO3_IO20 0x17059

};

hog {

pinctrl_hog: hoggrp {

fsl,pins = <

MX6SL_PAD_KEY_ROW7__GPIO4_IO07 0x17059

Re: Re: Re: Problems modifying device tree to blink an LED

fabio_estevam — Thu, 06 Feb 2014 21:14:22 GMT

Here is a patch against 3.10.17.

I won't have access to my mx6slevk until tomorrow to test it.

Re: Problems modifying device tree to blink an LED

rathben — Thu, 06 Feb 2014 21:47:26 GMT

thanks for the patch, but same non-working result

Re: Problems modifying device tree to blink an LED

fabio_estevam — Thu, 06 Feb 2014 22:07:22 GMT

Ben,

Today I tested 3.14-rc1 and got the LEDs blinking on my mx6slevk at the office.

Running the same 3.14-rc1 kernel and dtb on the mx6slevk I have at home I got no LED blinking.

I don't have a scope here at home to measure the signals. The evk I have at home is an old version (it is a red one).

Tomorrow I will try 3.10 with the evk from the office.

Regards,

Fabio Estevam

Re: Problems modifying device tree to blink an LED

fabio_estevam — Fri, 07 Feb 2014 15:52:54 GMT

Ok, so I tested on 3.10 and I see the same behavior as you reported: LED blinks once and then stops.

If I run 3.14-rc1 it works fine though.

Also tested 3.10.17 on a mx53qsb and the LED blinks fine.

I haven't had a chance to debug this.

Regards,

Fabio Estevam

Re: Problems modifying device tree to blink an LED

rathben — Fri, 07 Feb 2014 17:06:48 GMT

well... I guess that is "good" news, at least we're seeing the same behavior and I'm apparently not totally insane :smileyhappy:. You might try commenting out the call to regulator_init_complete (same as I did) to see that it works afterwards. Perhaps someone shedding some light on what this function does might help to debug the situation. Thanks!

Re: Problems modifying device tree to blink an LED

fabio_estevam — Tue, 18 Feb 2014 19:46:42 GMT

Ben,

Please try this patch that I have just submitted:

'[PATCH] ARM: dts: imx6sl-evk: Keep VGEN1 regulator always enabled' - MARC

Regards,

Fabio Estevam