From: James Clark Date: Fri, 27 Jun 2025 10:21:37 +0000 (+0100) Subject: spi: spi-fsl-dspi: Clear completion counter before initiating transfer X-Git-Tag: v6.16-rc5~18^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fa60c094c19b97e103d653f528f8d9c178b6a5f5;p=thirdparty%2Fkernel%2Flinux.git spi: spi-fsl-dspi: Clear completion counter before initiating transfer In target mode, extra interrupts can be received between the end of a transfer and halting the module if the host continues sending more data. If the interrupt from this occurs after the reinit_completion() then the completion counter is left at a non-zero value. The next unrelated transfer initiated by userspace will then complete immediately without waiting for the interrupt or writing to the RX buffer. Fix it by resetting the counter before the transfer so that lingering values are cleared. This is done after clearing the FIFOs and the status register but before the transfer is initiated, so no interrupts should be received at this point resulting in other race conditions. Fixes: 4f5ee75ea171 ("spi: spi-fsl-dspi: Replace interruptible wait queue with a simple completion") Signed-off-by: James Clark Reviewed-by: Frank Li Link: https://patch.msgid.link/20250627-james-nxp-spi-dma-v4-1-178dba20c120@linaro.org Signed-off-by: Mark Brown --- diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c index 863781ba6c160..0dcd491140950 100644 --- a/drivers/spi/spi-fsl-dspi.c +++ b/drivers/spi/spi-fsl-dspi.c @@ -983,11 +983,20 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr, if (dspi->devtype_data->trans_mode == DSPI_DMA_MODE) { status = dspi_dma_xfer(dspi); } else { + /* + * Reinitialize the completion before transferring data + * to avoid the case where it might remain in the done + * state due to a spurious interrupt from a previous + * transfer. This could falsely signal that the current + * transfer has completed. + */ + if (dspi->irq) + reinit_completion(&dspi->xfer_done); + dspi_fifo_write(dspi); if (dspi->irq) { wait_for_completion(&dspi->xfer_done); - reinit_completion(&dspi->xfer_done); } else { do { status = dspi_poll(dspi);