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Fix SPI clock and reinit on i.MX RT #11622

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Merged
dhalbert merged 2 commits into from
Oct 18, 2026
Merged

Fix SPI clock and reinit on i.MX RT #11622

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78a09c8
Use the selected LPSPI clock source on i.MX RT
lynt-smitka Oct 16, 2026
2f39165
Skip SPI reinit when the settings are unchanged
lynt-smitka Oct 16, 2026
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16 changes: 13 additions & 3 deletions ports/mimxrt10xx/common-hal/busio/SPI.c
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,15 @@
#if IMXRT11XX
#define LPSPI_MASTER_CLK_FREQ (24000000)
#else
#define LPSPI_MASTER_CLK_FREQ (CLOCK_GetFreq(kCLOCK_Usb1PllPfd0Clk) / (CLOCK_GetDiv(kCLOCK_LpspiDiv) + 1))
#define LPSPI_MASTER_CLK_FREQ (lpspi_clock_freq())

static uint32_t lpspi_clock_freq(void) {
// Indexed by the LPSPI_CLK_SEL mux setting.
static const clock_name_t sources[] = {
kCLOCK_Usb1PllPfd1Clk, kCLOCK_Usb1PllPfd0Clk, kCLOCK_SysPllClk, kCLOCK_SysPllPfd2Clk
};
return CLOCK_GetFreq(sources[CLOCK_GetMux(kCLOCK_LpspiMux)]) / (CLOCK_GetDiv(kCLOCK_LpspiDiv) + 1);
}
#endif

#define MAX_SPI_BUSY_RETRIES 100
Expand Down Expand Up @@ -169,6 +177,7 @@ void common_hal_busio_spi_construct(busio_spi_obj_t *self,
// Always start at 250khz which is what SD cards need. They are sensitive to
// SPI bus noise before they are put into SPI mode.
config.baudRate = 250000;
self->target_frequency = config.baudRate;
LPSPI_MasterInit(self->spi, &config, LPSPI_MASTER_CLK_FREQ);
LPSPI_Enable(self->spi, false);
uint32_t tcrPrescaleValue;
Expand Down Expand Up @@ -219,8 +228,8 @@ bool common_hal_busio_spi_configure(busio_spi_obj_t *self,

if ((polarity == common_hal_busio_spi_get_polarity(self)) &&
(phase == common_hal_busio_spi_get_phase(self)) &&
(bits == ((self->spi->TCR & LPSPI_TCR_FRAMESZ_MASK) >> LPSPI_TCR_FRAMESZ_SHIFT)) + 1 &&
(baudrate == common_hal_busio_spi_get_frequency(self))) {
(bits == ((self->spi->TCR & LPSPI_TCR_FRAMESZ_MASK) >> LPSPI_TCR_FRAMESZ_SHIFT) + 1) &&
(baudrate == self->target_frequency)) {
return true;
}

Expand All @@ -246,6 +255,7 @@ bool common_hal_busio_spi_configure(busio_spi_obj_t *self,
LPSPI_Enable(self->spi, false);
self->baudrate = LPSPI_MasterSetBaudRate(self->spi, baudrate, LPSPI_MASTER_CLK_FREQ, &tcrPrescaleValue);
LPSPI_Enable(self->spi, true);
self->target_frequency = baudrate;

return true;
}
Expand Down
1 change: 1 addition & 0 deletions ports/mimxrt10xx/common-hal/busio/SPI.h
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ typedef struct {
LPSPI_Type *spi;
bool has_lock;
uint32_t baudrate;
uint32_t target_frequency;
const mcu_periph_obj_t *clock;
const mcu_periph_obj_t *mosi;
const mcu_periph_obj_t *miso;
Expand Down
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