From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: [PATCH 5/5] megaraid_sas: add mmio barrier after register writes Date: Fri, 11 Nov 2016 10:44:52 +0100 Message-ID: <1478857492-4581-6-git-send-email-hare@suse.de> References: <1478857492-4581-1-git-send-email-hare@suse.de> Return-path: Received: from mx2.suse.de ([195.135.220.15]:60661 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754978AbcKKJpH (ORCPT ); Fri, 11 Nov 2016 04:45:07 -0500 In-Reply-To: <1478857492-4581-1-git-send-email-hare@suse.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Martin K. Petersen" Cc: Christoph Hellwig , James Bottomley , Sumit Saxena , linux-scsi@vger.kernel.org, Hannes Reinecke , Hannes Reinecke The megaraid_sas HBA only has a single register for I/O submission, which will be hit pretty hard with scsi-mq. To ensure that the PCI writes have made it across we need to add a mmio barrier after each write; otherwise I've been seeing spurious command completions and I/O stalls. Signed-off-by: Hannes Reinecke --- drivers/scsi/megaraid/megaraid_sas_fusion.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c index aba53c0..729a654 100644 --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c @@ -196,6 +196,7 @@ inline void megasas_return_cmd_fusion(struct megasas_instance *instance, le32_to_cpu(req_desc->u.low)); writeq(req_data, &instance->reg_set->inbound_low_queue_port); + mmiowb(); #else unsigned long flags; -- 1.8.5.6