IMX6 dual GPIO Configuration

[mariyapradeep]

Hi,
I am using imx6 dual wandboard. I wanted to configure some pins as GPIO. I tested by using LEDS. By default in dts file 8 pins are configured as GPIO of which 2 pins MX6QDL_PAD_EIM_DA12__GPIO3_IO12 and MX6QDL_PAD_GPIO_18__GPIO7_IO13 are not getting configured properly. For the other 6 pins the leds blinks as I toggle using /sys/class/gpio, but on reading the value am getting some garbage values. With reference to this post: http://forums.wandboard.org/viewtopic.php?f=8&t=893 made some changes in imx6qdl.dtsi to the end.

&iomuxc {
pinctrl-names = "default";
pinctrl-0 = <
&pinctrl_hog_1
&wes_gpios
>;

imx6qdl-wandboard {
wes_gpios: hoggrp-2 {
fsl,pins = <
MX6QDL_PAD_EIM_DA12__GPIO3_IO12 0x4001b0b0 /* GPIO3_12 EDM pin 255 */
MX6QDL_PAD_EIM_D27__GPIO3_IO27 0x4001b0b0 /* GPIO3_27 EDM pin 258 */
MX6QDL_PAD_EIM_BCLK__GPIO6_IO31 0x4001b0b0 /* GPIO6_31 EDM pin 260 */
MX6QDL_PAD_ENET_RX_ER__GPIO1_IO24 0x4001b0b0 /* GPIO1_24 EDM pin 262 */
MX6QDL_PAD_SD3_RST__GPIO7_IO08 0x4001b0b0 /* GPIO7_8 EDM pin 264 */
MX6QDL_PAD_EIM_D26__GPIO3_IO26 0x4001b0b0 /* GPIO3_26 EDM pin 259 */
MX6QDL_PAD_GPIO_18__GPIO7_IO13 0x4001b0b0 /* GPIO7_13 */
MX6QDL_PAD_GPIO_19__GPIO4_IO05 0x4001b0b0 /* GPIO4_5 EDM pin 263 */
>;
};
};
};

but still the 2 pins MX6QDL_PAD_EIM_DA12__GPIO3_IO12 and MX6QDL_PAD_GPIO_18__GPIO7_IO13 are not working as intended, I tried to access pin MX6QDL_PAD_EIM_DA12__GPIO3_IO12
via user space here is the log:

~# echo 76 > /sys/class/gpio/export
~# echo "out" > /sys/class/gpio/gpio76/direction
~# echo 1 > /sys/class/gpio/gpio76/value
~# cat /sys/class/gpio/gpio76/value
4096

I'm having similar issue with MX6QDL_PAD_GPIO_18__GPIO7_IO13 also. Can anyone tell me why this value is coming?
Is there anything more I need to do to get it configured as GPIO?

Thanks in advance

[BiyongSUN]

Simple GPIO Example - quandry
https://community.freescale.com/message/598834#598834

[fabio_estevam]

Looks like this bug has already been fixed in recent kernels. Please try 4.1.15.

[fabio_estevam]

Here is the commit that fixes this bug:

commit 25b35da7f4cce82271859f1b6eabd9f3bd41a2bb
Author: Linus Walleij <linus.walleij@linaro.org>
Date: Wed Feb 5 14:08:02 2014 +0100

gpio: generic: clamp retured value to [0,1]

The generic GPIO would return 0 for low generic GPIO, and
something != 0 for high GPIO. Let's make this sane by clamping
the returned value to [0,1].

Reported-by: Evgeny Boger <boger@contactless.ru>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpio-generic.c b/drivers/gpio/gpio-generic.c
index 8c778af..d815dd2 100644
--- a/drivers/gpio/gpio-generic.c
+++ b/drivers/gpio/gpio-generic.c
@@ -139,7 +139,7 @@ static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
{
struct bgpio_chip *bgc = to_bgpio_chip(gc);

- return bgc->read_reg(bgc->reg_dat) & bgc->pin2mask(bgc, gpio);
+ return !!(bgc->read_reg(bgc->reg_dat) & bgc->pin2mask(bgc, gpio));
}

This commit hit mainline kernel in 3.15 version.

[mariyapradeep]

Hi,

    I am using kernel 3.14. I applied the above said changes and got the values 0 and 1 on toggling the GPIO. But am not able to get GPIO functionality from 2 pins MX6QDL_PAD_EIM_DA12__GPIO3_IO12 and MX6QDL_PAD_GPIO_18__GPIO7_IO13.

Is there any configurations am missing?

[igorpadykov]

Hi Mariya

probably these lines are used somewhere by other modules

or configured in uboot, one can try to attached jtag (or printf)

iomux settings of these pads.

Best regards
igor
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