Merge branch 'spi-5.3' into spi-linus

1 files changed, 12 insertions, 2 deletions

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 840b1b8ff3dc..dfdcebb38830 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -319,6 +319,13 @@ static void bcm2835_spi_reset_hw(struct spi_controller *ctlr)
                 BCM2835_SPI_CS_INTD |
                 BCM2835_SPI_CS_DMAEN |
                 BCM2835_SPI_CS_TA);
+        /*
+         * Transmission sometimes breaks unless the DONE bit is written at the
+         * end of every transfer.  The spec says it's a RO bit.  Either the
+         * spec is wrong and the bit is actually of type RW1C, or it's a
+         * hardware erratum.
+         */
+        cs |= BCM2835_SPI_CS_DONE;
         /* and reset RX/TX FIFOS */
         cs |= BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX;
 
@@ -477,7 +484,9 @@ static void bcm2835_spi_transfer_prologue(struct spi_controller *ctlr,
                 bcm2835_wr_fifo_count(bs, bs->rx_prologue);
                 bcm2835_wait_tx_fifo_empty(bs);
                 bcm2835_rd_fifo_count(bs, bs->rx_prologue);
-                bcm2835_spi_reset_hw(ctlr);
+                bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_CLEAR_RX
+                                                  | BCM2835_SPI_CS_CLEAR_TX
+                                                  | BCM2835_SPI_CS_DONE);
 
                 dma_sync_single_for_device(ctlr->dma_rx->device->dev,
                                            sg_dma_address(&tfr->rx_sg.sgl[0]),
@@ -498,7 +507,8 @@ static void bcm2835_spi_transfer_prologue(struct spi_controller *ctlr,
                                                   | BCM2835_SPI_CS_DMAEN);
                 bcm2835_wr_fifo_count(bs, tx_remaining);
                 bcm2835_wait_tx_fifo_empty(bs);
-                bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_CLEAR_TX);
+                bcm2835_wr(bs, BCM2835_SPI_CS, cs | BCM2835_SPI_CS_CLEAR_TX
+                                                  | BCM2835_SPI_CS_DONE);
         }
 
         if (likely(!bs->tx_spillover)) {