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 <ilias.apalodi...@linaro.org> Reported-by: Ard Biesheuvel <ard.biesheu...@linaro.org> --- drivers/net/ethernet/socionext/netsec.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c index 7aa5ebb..4289ccb 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 -- 2.7.4