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stm32:Etablish device before enabling outputs

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This prevents gliches on changing to an output mode.
   If not the ALT mux can be selecting a IP block that
   is drving the line to say 0. Then the output is connected
   to that source, then swithced to the correct source. This
   produced a 430 nS glich on a F4 @168 Mhz. It was a enough
   to corrupt an I2C device with a bus monitor.
This commit is contained in:
David Sidrane 2021-09-16 10:43:59 -07:00 committed by Xiang Xiao
parent 0504e1d5f6
commit d5e306e6f3
1 changed files with 57 additions and 24 deletions
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53
arch/arm/src/stm32/stm32_gpio.c
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@ -406,6 +406,7 @@ int stm32_configgpio(uint32_t cfgset)
uintptr_t base;
uint32_t regval;
uint32_t setting;
uint32_t alt_setting;
unsigned int regoffset;
unsigned int port;
unsigned int pin;
@ -463,6 +464,41 @@ int stm32_configgpio(uint32_t cfgset)
flags = enter_critical_section();
/* Determine the alternate function (Only alternate function pins) */
if (pinmode == GPIO_MODER_ALT)
{
alt_setting = (cfgset & GPIO_AF_MASK) >> GPIO_AF_SHIFT;
}
else
{
alt_setting = 0;
}
/* Set the alternate function (Only alternate function pins)
* This is done before configuring the Outputs on a change to
* an Alternate function.
*/
if (alt_setting != 0)
{
if (pin < 8)
{
regoffset = STM32_GPIO_AFRL_OFFSET;
pos = pin;
}
else
{
regoffset = STM32_GPIO_AFRH_OFFSET;
pos = pin - 8;
}
regval = getreg32(base + regoffset);
regval &= ~GPIO_AFR_MASK(pos);
regval |= (alt_setting << GPIO_AFR_SHIFT(pos));
putreg32(regval, base + regoffset);
}
/* Now apply the configuration to the mode register */
regval = getreg32(base + STM32_GPIO_MODER_OFFSET);
@ -496,17 +532,13 @@ int stm32_configgpio(uint32_t cfgset)
regval |= (setting << GPIO_PUPDR_SHIFT(pin));
putreg32(regval, base + STM32_GPIO_PUPDR_OFFSET);
/* Set the alternate function (Only alternate function pins) */
/* Set the alternate function (Only alternate function pins)
* This is done after configuring the the pin's connection
* on a change away from an Alternate function.
*/
if (pinmode == GPIO_MODER_ALT)
if (alt_setting == 0)
{
setting = (cfgset & GPIO_AF_MASK) >> GPIO_AF_SHIFT;
}
else
{
setting = 0;
}
if (pin < 8)
{
regoffset = STM32_GPIO_AFRL_OFFSET;
@ -520,8 +552,9 @@ int stm32_configgpio(uint32_t cfgset)
regval = getreg32(base + regoffset);
regval &= ~GPIO_AFR_MASK(pos);
regval |= (setting << GPIO_AFR_SHIFT(pos));
regval |= (alt_setting << GPIO_AFR_SHIFT(pos));
putreg32(regval, base + regoffset);
}
/* Set speed (Only outputs and alternate function pins) */