If the cache model is VIVT, DMA data transfers may not be valid and to ensure the validity of the data cache must be flushed and invalidated.
Signed-off-by: Radu Pirea <[email protected]> --- drivers/spi/spi-atmel.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index 4e5e51f..cda6d0f 100644 --- a/drivers/spi/spi-atmel.c +++ b/drivers/spi/spi-atmel.c @@ -21,6 +21,8 @@ #include <linux/slab.h> #include <linux/platform_data/dma-atmel.h> #include <linux/of.h> +#include <asm/cacheflush.h> +#include <asm/cachetype.h> #include <linux/io.h> #include <linux/gpio.h> @@ -742,6 +744,18 @@ static int atmel_spi_next_xfer_dma_submit(struct spi_master *master, xfer->bits_per_word)) goto err_exit; +#ifdef CONFIG_SOC_SAM_V4_V5 + /* + * On Atmel SoCs based on ARM9 cores, the data cache follows the VIVT + * model, hence the cache aliases issue can occur when buffers are + * allocated from DMA-unsafe areas, by vmalloc() for instance, where + * cache coherency is not taken into account or at least not handled + * completely (cache lines of aliases are not flushed and invalidated). + * This is not a theorical issue: it was reproduced when trying to mount + * a UBI file-system on a at91sam9g35ek board. + */ + flush_kernel_vmap_range((void *)xfer->rx_buf, xfer->len); +#endif /* Send both scatterlists */ rxdesc = dmaengine_prep_slave_sg(rxchan, xfer->rx_sg.sgl, xfer->rx_sg.nents, @@ -750,6 +764,9 @@ static int atmel_spi_next_xfer_dma_submit(struct spi_master *master, if (!rxdesc) goto err_dma; +#ifdef CONFIG_SOC_SAM_V4_V5 + flush_kernel_vmap_range((void *)xfer->tx_buf, xfer->len); +#endif txdesc = dmaengine_prep_slave_sg(txchan, xfer->tx_sg.sgl, xfer->tx_sg.nents, DMA_TO_DEVICE, @@ -779,6 +796,9 @@ static int atmel_spi_next_xfer_dma_submit(struct spi_master *master, rxchan->device->device_issue_pending(rxchan); txchan->device->device_issue_pending(txchan); +#ifdef CONFIG_SOC_SAM_V4_V5 + invalidate_kernel_vmap_range((void *)xfer->rx_buf, xfer->len); +#endif /* take back lock */ atmel_spi_lock(as); return 0; -- 2.7.4
