[PATCH] spi: dw-dma: Wait for controller idle before completing Tx

[PATCH] spi: dw-dma: Wait for controller idle before completing Tx

[Wang YuWei]

dw_spi_dma_wait_tx_done() polls dw_spi_dma_tx_busy(), which only checks
DW_SPI_SR_TF_EMPT. An empty TX FIFO merely means the last data word has
been moved into the shift register; the transfer is not complete on the
bus until DW_SPI_SR_BUSY is also cleared. As a result the wait can
return while the controller is still shifting out the final word.

Any caller that tears down or reconfigures the controller right after
the transfer can then lose the tail of the transfer.

The memory-operation path in spi-dw-core.c already waits for both
DW_SPI_SR_BUSY == 0 and DW_SPI_SR_TF_EMPT == 1. Use the same completion
condition in the DMA path so the transfer is guaranteed to be finished
on the bus before the wait returns.

Signed-off-by: Wang YuWei <1973615295@qq.com>
---
 drivers/spi/spi-dw-dma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index bd70a7ed8067..f7d848fec9ab 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -282,7 +282,8 @@ static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)
 
 static inline bool dw_spi_dma_tx_busy(struct dw_spi *dws)
 {
-	return !(dw_readl(dws, DW_SPI_SR) & DW_SPI_SR_TF_EMPT);
+	return (dw_readl(dws, DW_SPI_SR) &
+		(DW_SPI_SR_BUSY | DW_SPI_SR_TF_EMPT)) != DW_SPI_SR_TF_EMPT;
 }
 
 static int dw_spi_dma_wait_tx_done(struct dw_spi *dws,
-- 
2.34.1

Re: [PATCH] spi: dw-dma: Wait for controller idle before completing Tx

[Mark Brown]

On Mon, 06 Jul 2026 11:33:13 +0800, Wang YuWei wrote:
> spi: dw-dma: Wait for controller idle before completing Tx

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-7.2

Thanks!

[1/1] spi: dw-dma: Wait for controller idle before completing Tx
      https://git.kernel.org/broonie/sound/c/0bcd59706aed

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark