From 2a1e89df785082a0fd7264ca6d3d834abe84fa25 Mon Sep 17 00:00:00 2001 From: Ilias Apalodimas Date: Thu, 11 Oct 2018 15:28:26 +0300 Subject: net: socionext: clear rx irq correctly commit 63ae7949e94a ("net: socionext: Use descriptor info instead of MMIO reads on Rx") removed constant mmio reads from the driver and started using a descriptor field to check if packet should be processed. This lead the napi rx handler being constantly called while no packets needed processing and ksoftirq getting 100% cpu usage. Issue one mmio read to clear the irq correcty after processing packets Signed-off-by: Ilias Apalodimas Reported-by: Ard Biesheuvel Tested-by: Ard Biesheuvel Acked-by: Ard Biesheuvel Signed-off-by: David S. Miller --- drivers/net/ethernet/socionext/netsec.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/net/ethernet/socionext') diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c index 7aa5ebb6766c..4289ccb26e4e 100644 --- a/drivers/net/ethernet/socionext/netsec.c +++ b/drivers/net/ethernet/socionext/netsec.c @@ -735,8 +735,11 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget) u16 idx = dring->tail; struct netsec_de *de = dring->vaddr + (DESC_SZ * idx); - if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD)) + if (de->attr & (1U << NETSEC_RX_PKT_OWN_FIELD)) { + /* reading the register clears the irq */ + netsec_read(priv, NETSEC_REG_NRM_RX_PKTCNT); break; + } /* This barrier is needed to keep us from reading * any other fields out of the netsec_de until we have -- cgit v1.2.3-59-g8ed1b