From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH v2] scsi: ufs: Implement Auto-Hibern8 setup Date: Wed, 26 Jul 2017 15:25:34 +0000 Message-ID: <1501082732.2671.5.camel@wdc.com> References: <20170725094514.19192-1-michalx.potomski@intel.com> <1500996626.3031.1.camel@wdc.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Received: from esa2.hgst.iphmx.com ([68.232.143.124]:38475 "EHLO esa2.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751451AbdGZP0V (ORCPT ); Wed, 26 Jul 2017 11:26:21 -0400 In-Reply-To: Content-Language: en-US Content-ID: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "michalx.potomski@intel.com" , "linux-scsi@vger.kernel.org" Cc: "jejb@linux.vnet.ibm.com" , "subhashj@codeaurora.org" , "szymonx.mielczarek@intel.com" , "martin.petersen@oracle.com" , "vinholikatti@gmail.com" On Tue, 2017-07-25 at 16:54 +0000, Potomski, MichalX wrote: > On Tue, 2017-07-25 at 15:30 +0000, Bart Van Assche wrote: > > Since I'm not familiar with the Auto-Hibern8 feature: what impact does = it > > have on command processing? Does it e.g. cause SCSI or TMF commands tha= t > > are > > sent to the UFS device to be ignored, to fail or to time out? >=20 > Actually behavior should be transparent for all of the higher layers, sin= ce this > shall be fully controlled by UFS Host, which will put UFS Device to Hiber= n8 state, > when it has no ongoing commands to it for set up time. If there will be a= ny command > UFS Host should order the Device to exit Hibern8 mode and proceed normall= y. >=20 > Bottom line is that in model case, it shouldn't cause any of errors menti= oned by you. > There is possible throughput degradation in case, if transfers are sporad= ic in terms > of timer, which we did set up, though. According to specification it also= shouldn't affect > Hibern8 states triggered by Power Management, nor any other functionality= . Hello Michal, SCSI requests can not only be initiated by user space but also by the kerne= l itself. Are SCSI UFS devices controlled by the SCSI disk (sd) driver? Will SCSI requests submitted by sd_check_events() to a hibernated UFS device tim= e out and activate the SCSI error handler? Thanks, Bart.=