sky2: memory barriers change
Do some memory barrier changes for safety/perfomance:
Don't need read after update to index, mmiowb() followed by read at end
of irq is sufficient.
Signed-off-by: Stephn Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index ccbd8c2..832fd69 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -844,10 +844,12 @@
/* Update chip's next pointer */
static inline void sky2_put_idx(struct sky2_hw *hw, unsigned q, u16 idx)
{
- q = Y2_QADDR(q, PREF_UNIT_PUT_IDX);
+ /* Make sure write' to descriptors are complete before we tell hardware */
wmb();
- sky2_write16(hw, q, idx);
- sky2_read16(hw, q);
+ sky2_write16(hw, Y2_QADDR(q, PREF_UNIT_PUT_IDX), idx);
+
+ /* Synchronize I/O on since next processor may write to tail */
+ mmiowb();
}
@@ -979,6 +981,7 @@
/* reset the Rx prefetch unit */
sky2_write32(hw, Y2_QADDR(rxq, PREF_UNIT_CTRL), PREF_UNIT_RST_SET);
+ mmiowb();
}
/* Clean out receive buffer area, assumes receiver hardware stopped */
@@ -1198,7 +1201,7 @@
}
/* Tell chip about available buffers */
- sky2_write16(hw, Y2_QADDR(rxq, PREF_UNIT_PUT_IDX), sky2->rx_put);
+ sky2_put_idx(hw, rxq, sky2->rx_put);
return 0;
nomem:
sky2_rx_clean(sky2);
@@ -1540,6 +1543,8 @@
}
sky2->tx_cons = idx;
+ smp_mb();
+
if (tx_avail(sky2) > MAX_SKB_TX_LE + 4)
netif_wake_queue(dev);
}
@@ -2218,6 +2223,7 @@
/* Fully processed status ring so clear irq */
sky2_write32(hw, STAT_CTRL, SC_STAT_CLR_IRQ);
+ mmiowb();
exit_loop:
if (buf_write[0]) {
@@ -2442,6 +2448,7 @@
if (work_done < work_limit) {
netif_rx_complete(dev0);
+ /* end of interrupt, re-enables also acts as I/O synchronization */
sky2_read32(hw, B0_Y2_SP_LISR);
return 0;
} else {
