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fix: SPI: remove holes between transfer() #288

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fix: SPI: remove holes between transfer() #288

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8862d4e
fix: SPI: remove holes between transfer()
facchinm Dec 10, 2025
1a62325
SPI: fix: avoid locks with 8/16 bit transfers
pillo79 Dec 18, 2025
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21 changes: 7 additions & 14 deletions libraries/SPI/SPI.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -13,28 +13,26 @@ arduino::ZephyrSPI::ZephyrSPI(const struct device *spi) : spi_dev(spi) {

uint8_t arduino::ZephyrSPI::transfer(uint8_t data) {
uint8_t rx = data;
if (transfer(&rx, sizeof(rx), &config) < 0) {
if (transfer(&rx, sizeof(rx), SPI_WORD_SET(8)) < 0) {
return 0;
}
return rx;
}

uint16_t arduino::ZephyrSPI::transfer16(uint16_t data) {
uint16_t rx = data;
if (transfer(&rx, sizeof(rx), &config16) < 0) {
if (transfer(&rx, sizeof(rx), SPI_WORD_SET(16)) < 0) {
return 0;
}
return rx;
}

void arduino::ZephyrSPI::transfer(void *buf, size_t count) {
int ret = transfer(buf, count, &config);
int ret = transfer(buf, count, SPI_WORD_SET(8));
(void)ret;
}

int arduino::ZephyrSPI::transfer(void *buf, size_t len, const struct spi_config *config) {
int ret;

int arduino::ZephyrSPI::transfer(void *buf, size_t len, uint32_t flags) {
const struct spi_buf tx_buf = {.buf = buf, .len = len};
const struct spi_buf_set tx_buf_set = {
.buffers = &tx_buf,
Expand All @@ -47,6 +45,7 @@ int arduino::ZephyrSPI::transfer(void *buf, size_t len, const struct spi_config
.count = 1,
};

config.operation = mode | flags;
return spi_transceive(spi_dev, config, &tx_buf_set, &rx_buf_set);
}

Expand All @@ -57,7 +56,7 @@ void arduino::ZephyrSPI::notUsingInterrupt(int interruptNumber) {
}

void arduino::ZephyrSPI::beginTransaction(SPISettings settings) {
uint32_t mode = 0;
mode = SPI_HOLD_ON_CS | SPI_LOCK_ON;

// Set bus mode
switch (settings.getBusMode()) {
Expand Down Expand Up @@ -93,15 +92,9 @@ void arduino::ZephyrSPI::beginTransaction(SPISettings settings) {
break;
}

// Set SPI configuration structure for 8-bit transfers
// Set SPI configuration structure except for operation
memset(&config, 0, sizeof(struct spi_config));
config.operation = mode | SPI_WORD_SET(8);
config.frequency = max(SPI_MIN_CLOCK_FREQUENCY, settings.getClockFreq());

// Set SPI configuration structure for 16-bit transfers
memset(&config16, 0, sizeof(struct spi_config));
config16.operation = mode | SPI_WORD_SET(16);
config16.frequency = max(SPI_MIN_CLOCK_FREQUENCY, settings.getClockFreq());
}

void arduino::ZephyrSPI::endTransaction(void) {
Expand Down
4 changes: 2 additions & 2 deletions libraries/SPI/SPI.h
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Original file line number Diff line number Diff line change
Expand Up @@ -59,12 +59,12 @@ class ZephyrSPI : public HardwareSPI {
virtual void end();

private:
int transfer(void *buf, size_t len, const struct spi_config *config);
int transfer(void *buf, size_t len, uint32_t flags);

protected:
const struct device *spi_dev;
struct spi_config config;
struct spi_config config16;
uint32_t mode;
int interrupt[INTERRUPT_COUNT];
size_t interrupt_pos = 0;
};
Expand Down