diff options
| -rw-r--r-- | drivers/spi/spi-bcm63xx.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/spi/spi-bcm63xx.c b/drivers/spi/spi-bcm63xx.c index da559b86f6b1..e05f8913ccda 100644 --- a/drivers/spi/spi-bcm63xx.c +++ b/drivers/spi/spi-bcm63xx.c @@ -257,6 +257,20 @@ static int bcm63xx_txrx_bufs(struct spi_device *spi, struct spi_transfer *first, if (t->rx_buf) { do_rx = true; + + /* + * In certain hardware implementations, there appears to be a + * hidden accumulator that tracks the number of bytes written into + * the hardware FIFO, and this accumulator overrides the length in + * the SPI_MSG_CTL register. + * + * Therefore, for read-only transfers, we need to write some dummy + * value into the FIFO to keep the accumulator tracking the correct + * length. + */ + if (!t->tx_buf) + memset_io(bs->tx_io + len, 0xFF, t->len); + /* prepend is half-duplex write only */ if (t == first) prepend_len = 0; |