BugLink: http://bugs.launchpad.net/bugs/1792044
Code includes barrier() 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 barrier().
Since code already has an explicit barrier call, changing writel() to
writel_relaxed() and adding mmiowb() for ordering protection.
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit
6d2e1a8d5e25e5f4563f5ea24bcb5da1ae261b26)
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
*/
wmb();
- writel(mmio_read_reg, ena_dev->reg_bar + ENA_REGS_MMIO_REG_READ_OFF);
+ writel_relaxed(mmio_read_reg,
+ ena_dev->reg_bar + ENA_REGS_MMIO_REG_READ_OFF);
+ mmiowb();
for (i = 0; i < timeout; i++) {
if (read_resp->req_id == mmio_read->seq_num)
break;
/* write the aenq doorbell after all AENQ descriptors were read */
mb();
- writel((u32)aenq->head, dev->reg_bar + ENA_REGS_AENQ_HEAD_DB_OFF);
+ writel_relaxed((u32)aenq->head,
+ dev->reg_bar + ENA_REGS_AENQ_HEAD_DB_OFF);
+ mmiowb();
}
int ena_com_dev_reset(struct ena_com_dev *ena_dev,
return io_sq->q_depth - 1 - cnt;
}
-static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq)
+static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq,
+ bool relaxed)
{
u16 tail;
pr_debug("write submission queue doorbell for queue: %d tail: %d\n",
io_sq->qid, tail);
- writel(tail, io_sq->db_addr);
+ if (relaxed)
+ writel_relaxed(tail, io_sq->db_addr);
+ else
+ writel(tail, io_sq->db_addr);
return 0;
}
* issue a doorbell
*/
wmb();
- ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq);
+ ena_com_write_sq_doorbell(rx_ring->ena_com_io_sq, true);
+ mmiowb();
}
rx_ring->next_to_use = next_to_use;
if (netif_xmit_stopped(txq) || !skb->xmit_more) {
/* trigger the dma engine */
- ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq);
+ ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq, false);
u64_stats_update_begin(&tx_ring->syncp);
tx_ring->tx_stats.doorbells++;
u64_stats_update_end(&tx_ring->syncp);