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stm32h7: spi: fix incorrect early transfer completion

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The semaphore was released after all bytes were read/written
without waiting for the EOT event, which is why the delay at
the end of the transfer needed to be longer than expected.

Change-Id: I6b48fc01cda69564c0ec8f843afd1b0c3a9c5a3c
This commit is contained in:
Aidan MacDonald 2026-01-01 18:22:26 +00:00
parent 46d644fcd7
commit 006859f16b
2 changed files with 15 additions and 5 deletions
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19
firmware/target/arm/stm32/spi-stm32h7.c
View file

@ -130,6 +130,7 @@ void stm_spi_init(struct stm_spi *spi,
spi->clock = config->clock;
spi->mode = config->mode;
spi->set_cs = config->set_cs;
spi->eot_delay_us = 1 + (1000000 / config->freq);
semaphore_init(&spi->sem, 1, 0);
@ -164,7 +165,6 @@ void stm_spi_init(struct stm_spi *spi,
stm32_clock_enable(spi->clock);
/* TODO: allow setting MBR here */
reg_writelf(spi->regs, SPI_CFG1,
MBR(mbr),
CRCEN(0),
@ -225,6 +225,8 @@ int stm_spi_xfer(struct stm_spi *spi, size_t size,
spi->rx_buf = rx_buf;
spi->rx_size = rx_buf ? size : 0;
membarrier();
stm_spi_enable(spi, hd_tx, size);
semaphore_wait(&spi->sem, TIMEOUT_BLOCK);
@ -236,10 +238,8 @@ int stm_spi_xfer(struct stm_spi *spi, size_t size,
* For 2.22.2 we need to wait at least 1 SCK cycle before starting the
* next transaction. For 2.22.6, waiting 1/2 SCK cycle should be enough
* since the EOT event is raised on a clock edge.
*
* TODO: calculate this delay time. doesn't seem to match assumptions above
*/
udelay(5);
udelay(spi->eot_delay_us);
stm_spi_disable(spi);
return 0;
@ -251,9 +251,13 @@ void stm_spi_irq_handler(struct stm_spi *spi)
{
uint32_t sr = reg_readl(spi->regs, SPI_SR);
if (spi->tx_size == 0 && spi->rx_size == 0)
if (spi->tx_size == 0 &&
spi->rx_size == 0 &&
reg_vreadf(sr, SPI_SR, EOT))
{
semaphore_release(&spi->sem);
reg_writelf(spi->regs, SPI_IFCR, EOTC(1));
reg_varl(spi->regs, SPI_IER) = 0;
return;
}
@ -261,6 +265,8 @@ void stm_spi_irq_handler(struct stm_spi *spi)
if (spi->tx_size > 0 && reg_vreadf(sr, SPI_SR, TXP))
{
uint32_t data = stm_spi_pack(&spi->tx_buf, &spi->tx_size);
if (spi->tx_size == 0)
reg_writelf(spi->regs, SPI_IER, TXPIE(0));
reg_varl(spi->regs, SPI_DR) = data;
continue;
@ -272,6 +278,9 @@ void stm_spi_irq_handler(struct stm_spi *spi)
uint32_t data = reg_readl(spi->regs, SPI_DR);
stm_spi_unpack(&spi->rx_buf, &spi->rx_size, data);
if (spi->rx_size == 0)
reg_writelf(spi->regs, SPI_IER, RXPIE(0));
continue;
}

1
firmware/target/arm/stm32/spi-stm32h7.h
View file

@ -81,6 +81,7 @@ struct stm_spi
enum stm_spi_mode mode;
stm_spi_set_cs_t set_cs;
uint32_t frame_size;
uint32_t eot_delay_us;
const void *tx_buf;
size_t tx_size;