From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ilias Apalodimas Subject: [PATCH 1/1] net: socionext: clear rx irq correctly Date: Thu, 11 Oct 2018 15:28:26 +0300 Message-ID: <1539260906-29596-1-git-send-email-ilias.apalodimas@linaro.org> Cc: ard.biesheuvel@linaro.org, masami.hiramatsu@linaro.org, Ilias Apalodimas To: netdev@vger.kernel.org, jaswinder.singh@linaro.org Return-path: Received: from mail-ed1-f68.google.com ([209.85.208.68]:37563 "EHLO mail-ed1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726212AbeJKTzh (ORCPT ); Thu, 11 Oct 2018 15:55:37 -0400 Received: by mail-ed1-f68.google.com with SMTP id c22-v6so8082487edc.4 for ; Thu, 11 Oct 2018 05:28:36 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: 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 --- 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