[PATCH net-next 07/12] net: bcmgenet: clear status to reduce spurious interrupts

Doug Berger
2017-03-14T00:42:35Z

Since the DMA interrupt status is latched and the DMA servicing can be
polled, it is a good idea to clear the latched status of a DMA interrupt
before performing the service that would be invoked by the interrupt.

This prevents old status from causing spurious interrupts when the
interrupt is unmasked at a later time.

Signed-off-by: Doug Berger <opendmb@gmail.com>
---
drivers/net/ethernet/broadcom/genet/bcmgenet.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index 661ca1b39c89..1f94ba1773dd 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -1174,6 +1174,14 @@ static unsigned int __bcmgenet_tx_reclaim(struct net_device *dev,
unsigned int txbds_ready;
unsigned int txbds_processed = 0;

+ /* Clear status before servicing to reduce spurious interrupts */
+ if (ring->index == DESC_INDEX)
+ bcmgenet_intrl2_0_writel(priv, UMAC_IRQ_TXDMA_DONE,
+ INTRL2_CPU_CLEAR);
+ else
+ bcmgenet_intrl2_1_writel(priv, (1 << ring->index),
+ INTRL2_CPU_CLEAR);
+
/* Compute how many buffers are transmitted since last xmit call */
c_index = bcmgenet_tdma_ring_readl(priv, ring->index, TDMA_CONS_INDEX)
& DMA_C_INDEX_MASK;
@@ -1584,10 +1592,21 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_rx_ring *ring,
unsigned long dma_flag;
int len;
unsigned int rxpktprocessed = 0, rxpkttoprocess;
- unsigned int p_index;
+ unsigned int p_index, mask;
unsigned int discards;
unsigned int chksum_ok = 0;

+ /* Clear status before servicing to reduce spurious interrupts */
+ if (ring->index == DESC_INDEX) {
+ bcmgenet_intrl2_0_writel(priv, UMAC_IRQ_RXDMA_DONE,
+ INTRL2_CPU_CLEAR);
+ } else {
+ mask = 1 << (UMAC_IRQ1_RX_INTR_SHIFT + ring->index);
+ bcmgenet_intrl2_1_writel(priv,
+ mask,
+ INTRL2_CPU_CLEAR);
+ }
+
p_index = bcmgenet_rdma_ring_readl(priv, ring->index, RDMA_PROD_INDEX);

discards = (p_index >> DMA_P_INDEX_DISCARD_CNT_SHIFT) &
--
2.11.1