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stm32mp1: add pull-up for gpio button PA13 and PA14

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When a push-button is released and PA13/PA14 are defined as input (high-Z)
the LED should not be active as the circuit is open but a small current
leak through PCB or push-button close the circuit and allows a small LED
bias giving erroneous level voltage.

So it is recommended to activate an internal pull-up in order to clearly
fix the voltage at PA13/PA14 when button is released and to wait
a short delay before to read the GPIO value only when the pull-up is
correctly configured.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
This commit is contained in:
Patrick Delaunay 2021-07-09 09:53:37 +02:00
parent 8b71b20e0e
commit 2a7034c77d
3 changed files with 6 additions and 4 deletions
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4
arch/arm/dts/stm32mp157a-dk1-u-boot.dtsi
View file

@ -17,8 +17,8 @@
u-boot,error-led = "error";
u-boot,mmc-env-partition = "ssbl";
st,adc_usb_pd = <&adc1 18>, <&adc1 19>;
st,fastboot-gpios = <&gpioa 13 GPIO_ACTIVE_LOW>;
st,stm32prog-gpios = <&gpioa 14 GPIO_ACTIVE_LOW>;
st,fastboot-gpios = <&gpioa 13 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
st,stm32prog-gpios = <&gpioa 14 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
};
firmware {

4
arch/arm/dts/stm32mp157c-ed1-u-boot.dtsi
View file

@ -16,8 +16,8 @@
u-boot,boot-led = "heartbeat";
u-boot,error-led = "error";
u-boot,mmc-env-partition = "ssbl";
st,fastboot-gpios = <&gpioa 13 GPIO_ACTIVE_LOW>;
st,stm32prog-gpios = <&gpioa 14 GPIO_ACTIVE_LOW>;
st,fastboot-gpios = <&gpioa 13 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
st,stm32prog-gpios = <&gpioa 14 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
};
firmware {

2
board/st/stm32mp1/stm32mp1.c
View file

@ -155,6 +155,7 @@ static void board_key_check(void)
&gpio, GPIOD_IS_IN)) {
log_debug("could not find a /config/st,fastboot-gpios\n");
} else {
udelay(20);
if (dm_gpio_get_value(&gpio)) {
log_notice("Fastboot key pressed, ");
boot_mode = BOOT_FASTBOOT;
@ -168,6 +169,7 @@ static void board_key_check(void)
&gpio, GPIOD_IS_IN)) {
log_debug("could not find a /config/st,stm32prog-gpios\n");
} else {
udelay(20);
if (dm_gpio_get_value(&gpio)) {
log_notice("STM32Programmer key pressed, ");
boot_mode = BOOT_STM32PROG;