The PL022 SPI driver maps the DMA RX buffer before the DMA TX buffer. In most cases, the sequence of the mapping does not matter. But in cases where TX and RX happen to use the same buffer, e.g., spidev, it causes the cached TX data not written to memory, because the same memory has been marked invalid when dma_map_sg on the RX buffer is called
The solution is to reverse the sequence so it maps the TX buffer before the RX buffer Signed-off-by: Ray Jui <[email protected]> Reviewed-by: JD (Jiandong) Zheng <[email protected]> Tested-by: Scott Branden <[email protected]> Reviewed-by: Scott Branden <[email protected]> --- drivers/spi/spi-pl022.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c index 1189cfd..edb7298 100644 --- a/drivers/spi/spi-pl022.c +++ b/drivers/spi/spi-pl022.c @@ -773,10 +773,10 @@ static void *next_transfer(struct pl022 *pl022) static void unmap_free_dma_scatter(struct pl022 *pl022) { /* Unmap and free the SG tables */ - dma_unmap_sg(pl022->dma_tx_channel->device->dev, pl022->sgt_tx.sgl, - pl022->sgt_tx.nents, DMA_TO_DEVICE); dma_unmap_sg(pl022->dma_rx_channel->device->dev, pl022->sgt_rx.sgl, pl022->sgt_rx.nents, DMA_FROM_DEVICE); + dma_unmap_sg(pl022->dma_tx_channel->device->dev, pl022->sgt_tx.sgl, + pl022->sgt_tx.nents, DMA_TO_DEVICE); sg_free_table(&pl022->sgt_rx); sg_free_table(&pl022->sgt_tx); } @@ -1026,16 +1026,16 @@ static int configure_dma(struct pl022 *pl022) pl022->cur_transfer->len, &pl022->sgt_tx); /* Map DMA buffers */ - rx_sglen = dma_map_sg(rxchan->device->dev, pl022->sgt_rx.sgl, - pl022->sgt_rx.nents, DMA_FROM_DEVICE); - if (!rx_sglen) - goto err_rx_sgmap; - tx_sglen = dma_map_sg(txchan->device->dev, pl022->sgt_tx.sgl, pl022->sgt_tx.nents, DMA_TO_DEVICE); if (!tx_sglen) goto err_tx_sgmap; + rx_sglen = dma_map_sg(rxchan->device->dev, pl022->sgt_rx.sgl, + pl022->sgt_rx.nents, DMA_FROM_DEVICE); + if (!rx_sglen) + goto err_rx_sgmap; + /* Send both scatterlists */ rxdesc = dmaengine_prep_slave_sg(rxchan, pl022->sgt_rx.sgl, @@ -1070,12 +1070,12 @@ err_txdesc: dmaengine_terminate_all(txchan); err_rxdesc: dmaengine_terminate_all(rxchan); + dma_unmap_sg(rxchan->device->dev, pl022->sgt_rx.sgl, + pl022->sgt_rx.nents, DMA_FROM_DEVICE); +err_rx_sgmap: dma_unmap_sg(txchan->device->dev, pl022->sgt_tx.sgl, pl022->sgt_tx.nents, DMA_TO_DEVICE); err_tx_sgmap: - dma_unmap_sg(rxchan->device->dev, pl022->sgt_rx.sgl, - pl022->sgt_tx.nents, DMA_FROM_DEVICE); -err_rx_sgmap: sg_free_table(&pl022->sgt_tx); err_alloc_tx_sg: sg_free_table(&pl022->sgt_rx); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
