Hi Patrick

On 7/9/21 9:53 AM, Patrick Delaunay wrote:

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

arch/arm/dts/stm32mp157a-dk1-u-boot.dtsi | 4 ++-- arch/arm/dts/stm32mp157c-ed1-u-boot.dtsi | 4 ++-- board/st/stm32mp1/stm32mp1.c | 2 ++ 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm/dts/stm32mp157a-dk1-u-boot.dtsi b/arch/arm/dts/stm32mp157a-dk1-u-boot.dtsi index 6787619290..d44da7566f 100644 --- a/arch/arm/dts/stm32mp157a-dk1-u-boot.dtsi +++ b/arch/arm/dts/stm32mp157a-dk1-u-boot.dtsi @@ -18,8 +18,8 @@ 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 {

diff --git a/arch/arm/dts/stm32mp157c-ed1-u-boot.dtsi b/arch/arm/dts/stm32mp157c-ed1-u-boot.dtsi index f3002e995b..3b94218b2f 100644 --- a/arch/arm/dts/stm32mp157c-ed1-u-boot.dtsi +++ b/arch/arm/dts/stm32mp157c-ed1-u-boot.dtsi @@ -18,8 +18,8 @@ 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 {

diff --git a/board/st/stm32mp1/stm32mp1.c b/board/st/stm32mp1/stm32mp1.c index 18b8870269..e1796e7e31 100644 --- a/board/st/stm32mp1/stm32mp1.c +++ b/board/st/stm32mp1/stm32mp1.c @@ -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;
  
  

Reviewed-by: Patrice Chotard patrice.chotard@foss.st.com

Thanks Patrice