ioatdma by default is in snoop mode. Relaxed ordering according to spec does not do anything in snoop mode. However, it causes hang or significant performance degrade when tested with NTB. Disabling in the driver due to some BIOS do not configure it correctly. Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx> --- drivers/dma/ioat/init.c | 12 ++++++++++++ drivers/dma/ioat/registers.h | 7 +++++++ 2 files changed, 19 insertions(+) diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c index efdee1a..7177199 100644 --- a/drivers/dma/ioat/init.c +++ b/drivers/dma/ioat/init.c @@ -1074,6 +1074,7 @@ static int ioat3_dma_probe(struct ioatdma_device *ioat_dma, int dca) struct ioatdma_chan *ioat_chan; bool is_raid_device = false; int err; + u16 val16; dma = &ioat_dma->dma_dev; dma->device_prep_dma_memcpy = ioat_dma_prep_memcpy_lock; @@ -1173,6 +1174,17 @@ static int ioat3_dma_probe(struct ioatdma_device *ioat_dma, int dca) if (dca) ioat_dma->dca = ioat_dca_init(pdev, ioat_dma->reg_base); + /* disable relaxed ordering */ + err = pcie_capability_read_word(pdev, IOAT_DEVCTRL_OFFSET, &val16); + if (err) + return err; + + /* clear relaxed ordering enable */ + val16 &= ~IOAT_DEVCTRL_ROE; + err = pcie_capability_write_word(pdev, IOAT_DEVCTRL_OFFSET, val16); + if (err) + return err; + return 0; } diff --git a/drivers/dma/ioat/registers.h b/drivers/dma/ioat/registers.h index 4994a36..7053498 100644 --- a/drivers/dma/ioat/registers.h +++ b/drivers/dma/ioat/registers.h @@ -26,6 +26,13 @@ #define IOAT_PCI_CHANERR_INT_OFFSET 0x180 #define IOAT_PCI_CHANERRMASK_INT_OFFSET 0x184 +/* PCIe config registers */ + +/* EXPCAPID + N */ +#define IOAT_DEVCTRL_OFFSET 0x8 +/* relaxed ordering enable */ +#define IOAT_DEVCTRL_ROE 0x10 + /* MMIO Device Registers */ #define IOAT_CHANCNT_OFFSET 0x00 /* 8-bit */ -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
