From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: [PATCH] scsi: associate bio write hint with WRITE CDB Date: Fri, 04 Jan 2019 01:11:49 -0500 Message-ID: References: <20181226041504.66283-1-huangrandall@google.com> <20190103075133.GA5141@infradead.org> <20190103094755.GA96532@google.com> <6152b478ea77dacf57eef6f758ba795f756cd3da.camel@redhat.com> <20190104052251.GA205256@google.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <20190104052251.GA205256@google.com> (Randall Huang's message of "Fri, 4 Jan 2019 13:22:51 +0800") Sender: linux-kernel-owner@vger.kernel.org To: Randall Huang Cc: "Martin K. Petersen" , jejb@linux.vnet.ibm.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, huangrandall@google.com List-Id: linux-scsi@vger.kernel.org Hi Randall, > I am working on Android phone. > The idea is to enable write hint for Turbo write UFS feature. Turbo > write feature in UFS 3.x is under discussion in JEDEC JC-64. This > patch is the under-lying framework for supporting this feature. OK, but we can't blindly go setting GROUP NUMBER to a non-zero value. That'll break a massive amount of devices which will fail READ/WRITE commands with INVALID FIELD IN CDB. So aside from requiring the device to report GROUP_SUP=1, we'll need some sort of indication that this device supports the UFS Turbo Write feature. If you are engaged with JEDEC on this, please tell them we'll need a VPD page, a mode page, or something similar to use as trigger to entertain enabling this feature. -- Martin K. Petersen Oracle Linux Engineering