From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754720AbbEMWBp (ORCPT ); Wed, 13 May 2015 18:01:45 -0400 Received: from skprod3.natinst.com ([130.164.80.24]:32784 "EHLO ni.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965113AbbEMWBn (ORCPT ); Wed, 13 May 2015 18:01:43 -0400 From: Nathan Sullivan To: nicolas.ferre@atmel.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Nathan Sullivan Subject: [PATCH] net: macb: Add better comment for RXUBR handling Date: Wed, 13 May 2015 17:01:36 -0500 Message-Id: <1431554496-11716-1-git-send-email-nathan.sullivan@ni.com> X-Mailer: git-send-email 1.7.10.4 X-MIMETrack: Itemize by SMTP Server on US-AUS-MGWOut2/AUS/H/NIC(Release 8.5.3FP6|November 21, 2013) at 05/13/2015 05:01:40 PM, Serialize by Router on US-AUS-MGWOut2/AUS/H/NIC(Release 8.5.3FP6|November 21, 2013) at 05/13/2015 05:01:41 PM, Serialize complete at 05/13/2015 05:01:41 PM X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2015-05-13_07:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Describe the handler for RXUBR better with a new comment. Signed-off-by: Nathan Sullivan Reviewied-by: Josh Cartwright Reviewied-by: Ben Shelton --- drivers/net/ethernet/cadence/macb.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c index 61aa570..5f10dfc 100644 --- a/drivers/net/ethernet/cadence/macb.c +++ b/drivers/net/ethernet/cadence/macb.c @@ -1037,6 +1037,12 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id) * add that if/when we get our hands on a full-blown MII PHY. */ + /* There is a hardware issue under heavy load where DMA can + * stop, this causes endless "used buffer descriptor read" + * interrupts but it can be cleared by re-enabling RX. See + * the at91 manual, section 41.3.1 or the Zynq manual + * section 16.7.4 for details. + */ if (status & MACB_BIT(RXUBR)) { ctrl = macb_readl(bp, NCR); macb_writel(bp, NCR, ctrl & ~MACB_BIT(RE)); -- 1.7.10.4