2022-01-09 17:22:32

by Christophe JAILLET

Subject: [PATCH] ixgbevf: Remove useless DMA-32 fallback configuration

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.

So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to be
1.

Simplify code and remove some dead code accordingly.

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

Signed-off-by: Christophe JAILLET <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Alexander Lobakin <[email protected]>
---
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 20 ++++++-------------
1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
index 0015fcf1df2b..7c33be9074e9 100644
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
@@ -4511,22 +4511,17 @@ static int ixgbevf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
struct ixgbevf_adapter *adapter = NULL;
struct ixgbe_hw *hw = NULL;
const struct ixgbevf_info *ii = ixgbevf_info_tbl[ent->driver_data];
- int err, pci_using_dac;
bool disable_dev = false;
+ int err;

err = pci_enable_device(pdev);
if (err)
return err;

- if (!dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64))) {
- pci_using_dac = 1;
- } else {
- err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
- if (err) {
- dev_err(&pdev->dev, "No usable DMA configuration, aborting\n");
- goto err_dma;
- }
- pci_using_dac = 0;
+ err = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+ if (err) {
+ dev_err(&pdev->dev, "No usable DMA configuration, aborting\n");
+ goto err_dma;
}

err = pci_request_regions(pdev, ixgbevf_driver_name);
@@ -4606,10 +4601,7 @@ static int ixgbevf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
netdev->hw_features |= NETIF_F_GSO_PARTIAL |
IXGBEVF_GSO_PARTIAL_FEATURES;

- netdev->features = netdev->hw_features;
-
- if (pci_using_dac)
- netdev->features |= NETIF_F_HIGHDMA;
+ netdev->features = netdev->hw_features | NETIF_F_HIGHDMA;

netdev->vlan_features |= netdev->features | NETIF_F_TSO_MANGLEID;
netdev->mpls_features |= NETIF_F_SG |
--
2.32.0

2022-01-13 17:48:53

by G, GurucharanX

Subject: RE: [Intel-wired-lan] [PATCH] ixgbevf: Remove useless DMA-32 fallback configuration

> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf Of
> Christophe JAILLET
> Sent: Sunday, January 9, 2022 10:52 PM
> To: Brandeburg, Jesse <[email protected]>; Nguyen, Anthony L
> <[email protected]>; David S. Miller <[email protected]>;
> Jakub Kicinski <[email protected]>
> Cc: [email protected]; [email protected]; linux-
> [email protected]; Christophe JAILLET
> <[email protected]>; [email protected]; Christoph
> Hellwig <[email protected]>
> Subject: [Intel-wired-lan] [PATCH] ixgbevf: Remove useless DMA-32 fallback
> configuration
>
> 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.
>
> So, if dma_set_mask_and_coherent() succeeds, 'pci_using_dac' is known to
> be 1.
>
> Simplify code and remove some dead code accordingly.
>
> [1]: https://lkml.org/lkml/2021/6/7/398
>
> Signed-off-by: Christophe JAILLET <[email protected]>
> Reviewed-by: Christoph Hellwig <[email protected]>
> Reviewed-by: Alexander Lobakin <[email protected]>
> ---
> .../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 20 ++++++-------------
> 1 file changed, 6 insertions(+), 14 deletions(-)
>

Tested-by: Gurucharan G <[email protected]> (A Contingent worker at Intel)