From mboxrd@z Thu Jan 1 00:00:00 1970 From: 'Christoph Hellwig' Subject: Re: [PATCH V3 01/16] scsi: support well known logical units Date: Sat, 13 Sep 2014 11:54:31 -0700 Message-ID: <20140913185431.GB30010@infradead.org> References: <1410350063-23267-1-git-send-email-draviv@codeaurora.org> <1410350063-23267-2-git-send-email-draviv@codeaurora.org> <20140910185839.GA26364@infradead.org> <000f01cfce22$446f79c0$cd4e6d40$@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <000f01cfce22$446f79c0$cd4e6d40$@codeaurora.org> Sender: linux-scsi-owner@vger.kernel.org To: Subhash Jadavani Cc: 'Christoph Hellwig' , 'Dolev Raviv' , James.Bottomley@HansenPartnership.com, linux-scsi@vger.kernel.org, linux-scsi-owner@vger.kernel.org, linux-arm-msm@vger.kernel.org, santoshsy@gmail.com, 'Sujit Reddy Thumma' , "'Martin K. Petersen'" List-Id: linux-arm-msm@vger.kernel.org On Thu, Sep 11, 2014 at 05:41:18PM -0700, Subhash Jadavani wrote: > > UFS device has supports 4 different well known logical units: "REPORT_LUNS" > (address: 01h), "UFS Device" (address: 50h), "RPMB" (address: 44h) and > "BOOT" (address: 30h). > > UFS device's power management needs to be controlled by "POWER CONDITION" > field of SSU (START STOP UNIT) command. But this "power condition" field > will take effect only when its sent to "UFS device" well known logical unit > (address: 50h) hence we require the scsi_device instance to represent this > logical unit in order for the UFS host driver to send the SSU command for > power management. > > We also require the scsi_device instance for "RPMB" (Replay Protected Memory > Block) LU so user space process can control this LU. If those are the only LUs you specificly need I'd suggest you just manually call scsi_add_device from your driver for those instead of listing them in REPORT_LUNS and making them part of the normal LUN scan. One advantage of the well known LUNs is that you always know where in the LUN namespace they are :)