There is a bug in the following patch:
http://comments.gmane.org/gmane.linux.kernel.spi.devel/14420
spi: DUAL and QUAD support
fix the previous patch some mistake below:
1. DT in slave node, use "spi-tx-nbits = <1/2/4>" in place of using
"spi-tx-dual, spi-tx-quad" directly, same to rx. So correct the
previous way to get the property in @of_register_spi_devices().
2. Change the value of transfer bit macro(SPI_NBITS_SINGLE, SPI_NBITS_DUAL
SPI_NBITS_QUAD) to 0x01, 0x02 and 0x04 to match the actual wires.
3. Add the following check
(1)keep the tx_nbits and rx_nbits in spi_transfer is not beyond the
single, dual and quad.
(2)keep tx_nbits and rx_nbits are contained by @spi_device->mode
example: if @spi_device->mode = DUAL, then tx/rx_nbits can not be set
to QUAD(SPI_NBITS_QUAD)
(3)if "@spi_device->mode & SPI_3WIRE", then tx/rx_nbits should be in
single(SPI_NBITS_SINGLE)
Checking of the tx/rx transfer bits and mode bits should be done conditionally
based on type of buffer filled else EINVAL condition will
always get hit either for rx or tx.
Signed-off-by: Sourav Poddar <sourav.pod...@ti.com>
---
This patch is developed on top of Mark Brown SPI tree[1]:
[1]: git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git
branch: remotes/brownspi/topic/quad
This branch has the parent patch with the bug.
drivers/spi/spi.c | 56 ++++++++++++++++++++++++++++------------------------
1 files changed, 30 insertions(+), 26 deletions(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 39d3875..50f7fc3 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1473,33 +1473,37 @@ static int __spi_async(struct spi_device *spi, struct
spi_message *message)
* 2. keep tx/rx_nbits is contained by mode in spi_device
* 3. if SPI_3WIRE, tx/rx_nbits should be in single
*/
- if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
- xfer->tx_nbits != SPI_NBITS_DUAL &&
- xfer->tx_nbits != SPI_NBITS_QUAD)
- return -EINVAL;
- if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
- !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
- return -EINVAL;
- if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
- !(spi->mode & SPI_TX_QUAD))
- return -EINVAL;
- if ((spi->mode & SPI_3WIRE) &&
- (xfer->tx_nbits != SPI_NBITS_SINGLE))
- return -EINVAL;
+ if (xfer->tx_buf) {
+ if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
+ xfer->tx_nbits != SPI_NBITS_DUAL &&
+ xfer->tx_nbits != SPI_NBITS_QUAD)
+ return -EINVAL;
+ if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
+ !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
+ return -EINVAL;
+ if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
+ !(spi->mode & SPI_TX_QUAD))
+ return -EINVAL;
+ if ((spi->mode & SPI_3WIRE) &&
+ (xfer->tx_nbits != SPI_NBITS_SINGLE))
+ return -EINVAL;
+ }
/* check transfer rx_nbits */
- if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
- xfer->rx_nbits != SPI_NBITS_DUAL &&
- xfer->rx_nbits != SPI_NBITS_QUAD)
- return -EINVAL;
- if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
- !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
- return -EINVAL;
- if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
- !(spi->mode & SPI_RX_QUAD))
- return -EINVAL;
- if ((spi->mode & SPI_3WIRE) &&
- (xfer->rx_nbits != SPI_NBITS_SINGLE))
- return -EINVAL;
+ if (xfer->rx_buf) {
+ if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
+ xfer->rx_nbits != SPI_NBITS_DUAL &&
+ xfer->rx_nbits != SPI_NBITS_QUAD)
+ return -EINVAL;
+ if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
+ !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
+ return -EINVAL;
+ if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
+ !(spi->mode & SPI_RX_QUAD))
+ return -EINVAL;
+ if ((spi->mode & SPI_3WIRE) &&
+ (xfer->rx_nbits != SPI_NBITS_SINGLE))
+ return -EINVAL;
+ }
}
message->spi = spi;
--
1.7.1
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