From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: [PATCH 0/3] hisi_sas: device id/IPTT collision workaround Date: Fri, 15 Apr 2016 16:56:27 -0400 Message-ID: References: <1460727398-102091-1-git-send-email-john.garry@huawei.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1460727398-102091-1-git-send-email-john.garry@huawei.com> (John Garry's message of "Fri, 15 Apr 2016 21:36:35 +0800") Sender: linux-kernel-owner@vger.kernel.org To: John Garry Cc: jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, linuxarm@huawei.com, john.garry2@mail.dcu.ie, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, zhangfei.gao@linaro.org List-Id: linux-scsi@vger.kernel.org >>>>> "John" == John Garry writes: John> This patchset introduces a workaround to a hw quirk in the John> HiSilicon SAS controller v2 hw. John> The quirk is as follows: When a SATA and SAS frame arrives at the John> host at the same time the frames may be swapped under this John> condition: SATA device id bit [10:0] == SAS frame IPTT bit [10:0] John> The workaround is to ensure these 2 values never match. The John> workaround algorithm is as follows: - SATA device id bit0 always 0 John> - SATA IPTT has no restriction - SAS IPTT bit0 always 1 - SAS John> device id has no restriction John> The major restriction of this workaround is the SAS IPTT range is John> halved, but this should be ok as testing has shown that even using John> half the IPTT range does not affect performance. Applied to 4.7/scsi-queue. Thanks! -- Martin K. Petersen Oracle Linux Engineering