Marking the DMA as cache coherent (dma-coherent in devicetree) is only safe with versions of axi_dmac that have this feature enabled. Cc: Lars-Peter Clausen <lars@xxxxxxxxxx> Cc: Nuno Sá <nuno.sa@xxxxxxxxxx> Signed-off-by: Mathias Tausen <mta@xxxxxxxxxx> --- For context, this patch is related to a recent change to the HDL: https://github.com/analogdevicesinc/hdl/pull/925 And has been discussed in the Analog Devices tree: https://github.com/analogdevicesinc/linux/pull/1908 drivers/dma/dma-axi-dmac.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c index 6aa5d383da21..1b78e54c2630 100644 --- a/drivers/dma/dma-axi-dmac.c +++ b/drivers/dma/dma-axi-dmac.c @@ -18,6 +18,7 @@ #include <linux/module.h> #include <linux/of.h> #include <linux/of_dma.h> +#include <linux/of_address.h> #include <linux/platform_device.h> #include <linux/regmap.h> #include <linux/slab.h> @@ -55,6 +56,9 @@ #define AXI_DMAC_DMA_DST_TYPE_GET(x) FIELD_GET(AXI_DMAC_DMA_DST_TYPE_MSK, x) #define AXI_DMAC_DMA_DST_WIDTH_MSK GENMASK(3, 0) #define AXI_DMAC_DMA_DST_WIDTH_GET(x) FIELD_GET(AXI_DMAC_DMA_DST_WIDTH_MSK, x) +#define AXI_DMAC_REG_COHERENCY_DESC 0x14 +#define AXI_DMAC_DST_COHERENT_MSK BIT(0) +#define AXI_DMAC_DST_COHERENT_GET(x) FIELD_GET(AXI_DMAC_DST_COHERENT_MSK, x) #define AXI_DMAC_REG_IRQ_MASK 0x80 #define AXI_DMAC_REG_IRQ_PENDING 0x84 @@ -1006,6 +1010,18 @@ static int axi_dmac_probe(struct platform_device *pdev) axi_dmac_write(dmac, AXI_DMAC_REG_IRQ_MASK, 0x00); + if (of_dma_is_coherent(pdev->dev.of_node)) { + ret = axi_dmac_read(dmac, AXI_DMAC_REG_COHERENCY_DESC); + + if (version < ADI_AXI_PCORE_VER(4, 4, 'a') || + !AXI_DMAC_DST_COHERENT_GET(ret)) { + dev_err(dmac->dma_dev.dev, + "Coherent DMA not supported in hardware"); + ret = -EINVAL; + goto err_clk_disable; + } + } + ret = dma_async_device_register(dma_dev); if (ret) goto err_clk_disable; -- 2.36.1
