[ Upstream commit 5442dcaa0d90fc376bdfc179a018931a8f43dea4 ]
This fixes a bug for messages containing both zero length and unidirectional xfers.
The function spi_map_msg will allocate dummy tx and/or rx buffers for use with unidirectional transfers when the hardware can only do a bidirectional transfer. That dummy buffer will be used in place of a NULL buffer even when the xfer length is 0.
Then in the function __spi_map_msg, if he hardware can dma, the zero length xfer will have spi_map_buf called on the dummy buffer.
Eventually, __sg_alloc_table is called and returns -EINVAL because nents == 0.
This fix prevents the error by not using the dummy buffer when the xfer length is zero.
Signed-off-by: Chris Lesiak chris.lesiak@licor.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/spi/spi.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index c2e85e23d538e..d74d341f9890d 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -955,6 +955,8 @@ static int spi_map_msg(struct spi_master *master, struct spi_message *msg) if (max_tx || max_rx) { list_for_each_entry(xfer, &msg->transfers, transfer_list) { + if (!xfer->len) + continue; if (!xfer->tx_buf) xfer->tx_buf = master->dummy_tx; if (!xfer->rx_buf)