openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

net: qlge: Eliminate duplicate barriers on weakly-ordered archs 

Code includes wmb() followed by writel(). writel() already has a barrier on
some architectures like arm64.

This ends up CPU observing two barriers back to back before executing the
register write.

Create a new wrapper function with relaxed write operator. Use the new
wrapper when a write is following a wmb().

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sinan Kaya 2018-03-25 10:39:19 -04:00 committed by David S. Miller
parent 7f883c774e
commit e42d8cee34
2 changed files with 18 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/net/ethernet/qlogic/qlge/qlge.h
View File

@ -2184,6 +2184,22 @@ static inline void ql_write_db_reg(u32 val, void __iomem *addr)
mmiowb();
}
/*
* Doorbell Registers:
* Doorbell registers are virtual registers in the PCI memory space.
* The space is allocated by the chip during PCI initialization. The
* device driver finds the doorbell address in BAR 3 in PCI config space.
* The registers are used to control outbound and inbound queues. For
* example, the producer index for an outbound queue. Each queue uses
* 1 4k chunk of memory. The lower half of the space is for outbound
* queues. The upper half is for inbound queues.
* Caller has to guarantee ordering.
*/
static inline void ql_write_db_reg_relaxed(u32 val, void __iomem *addr)
{
writel_relaxed(val, addr);
}
/*
* Shadow Registers:
* Outbound queues have a consumer index that is maintained by the chip.

3
drivers/net/ethernet/qlogic/qlge/qlge_main.c
View File

@ -2700,7 +2700,8 @@ static netdev_tx_t qlge_send(struct sk_buff *skb, struct net_device *ndev)
tx_ring->prod_idx = 0;
wmb();
ql_write_db_reg(tx_ring->prod_idx, tx_ring->prod_idx_db_reg);
ql_write_db_reg_relaxed(tx_ring->prod_idx, tx_ring->prod_idx_db_reg);
mmiowb();
netif_printk(qdev, tx_queued, KERN_DEBUG, qdev->ndev,
"tx queued, slot %d, len %d\n",
tx_ring->prod_idx, skb->len);