[dpdk-stable] [PATCH RFC v1 5/6] net/mlx5: non-cacheable mapping defaulted for aarch64

[Gavin Hu <gavin.hu@arm.com>]

aarch64 does not map pci resources to 'write-combine' nor
cacheable. In Linux Kernel arch_can_pci_mmap_wc() equals to 0 on
aarch64[1].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
tree/drivers/pci/pci-sysfs.c?h=v5.4#n1204

Fixes: f078ceb6ae93 ("net/mlx5: fix Tx doorbell write memory barrier")
Cc: stable@dpdk.org

Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
---
 drivers/net/mlx5/mlx5_txq.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/mlx5/mlx5_txq.c b/drivers/net/mlx5/mlx5_txq.c
index bc13abfe6..144bab4a6 100644
--- a/drivers/net/mlx5/mlx5_txq.c
+++ b/drivers/net/mlx5/mlx5_txq.c
@@ -319,7 +319,11 @@ txq_uar_ncattr_init(struct mlx5_txq_ctrl *txq_ctrl, size_t page_size)
 	off_t cmd;
 
 	txq_ctrl->txq.db_heu = priv->config.dbnc == MLX5_TXDB_HEURISTIC;
+#ifdef RTE_ARCH_ARM64
+	txq_ctrl->txq.db_nc = 1;
+#else
 	txq_ctrl->txq.db_nc = 0;
+#endif
 	/* Check the doorbell register mapping type. */
 	cmd = txq_ctrl->uar_mmap_offset / page_size;
 	cmd >>= MLX5_UAR_MMAP_CMD_SHIFT;
-- 
2.17.1