1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/spi/spi-bcm63xx.c b/drivers/spi/spi-bcm63xx.c
index b56210734caa..2e3c62f12bef 100644
--- a/drivers/spi/spi-bcm63xx.c
+++ b/drivers/spi/spi-bcm63xx.c
@@ -247,6 +247,20 @@ 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;