[PATCH] IB/mthca: Remove useless DMA-32 fallback configuration

[PATCH] IB/mthca: Remove useless DMA-32 fallback configuration

[Christophe JAILLET]

As stated in [1], dma_set_mask() with a 64-bit mask never fails if
dev->dma_mask is non-NULL.
So, if it fails, the 32 bits case will also fail for the same reason.

Simplify code and remove some dead code accordingly.

[1]: https://lkml.org/lkml/2021/6/7/398

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/infiniband/hw/mthca/mthca_main.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/hw/mthca/mthca_main.c b/drivers/infiniband/hw/mthca/mthca_main.c
index f507c4cd46d3..b54bc8865dae 100644
--- a/drivers/infiniband/hw/mthca/mthca_main.c
+++ b/drivers/infiniband/hw/mthca/mthca_main.c
@@ -939,12 +939,8 @@ static int __mthca_init_one(struct pci_dev *pdev, int hca_type)
 
 	err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
 	if (err) {
-		dev_warn(&pdev->dev, "Warning: couldn't set 64-bit PCI DMA mask.\n");
-		err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
-		if (err) {
-			dev_err(&pdev->dev, "Can't set PCI DMA mask, aborting.\n");
-			goto err_free_res;
-		}
+		dev_err(&pdev->dev, "Can't set PCI DMA mask, aborting.\n");
+		goto err_free_res;
 	}
 
 	/* We can handle large RDMA requests, so allow larger segments. */
-- 
2.32.0

Re: [PATCH] IB/mthca: Remove useless DMA-32 fallback configuration

[Jason Gunthorpe]

On Sun, Jan 09, 2022 at 09:30:09AM +0100, Christophe JAILLET wrote:
> As stated in [1], dma_set_mask() with a 64-bit mask never fails if
> dev->dma_mask is non-NULL.
> So, if it fails, the 32 bits case will also fail for the same reason.
> 
> Simplify code and remove some dead code accordingly.
> 
> [1]: https://lkml.org/lkml/2021/6/7/398

Can you use lore links please?

Jason