From: "Rafael J. Wysocki" Subject: Re: [PATCH v7 2/6] scsi: sr: support runtime pm Date: Sun, 30 Sep 2012 00:31:04 +0200 Message-ID: <201209300031.04419.rjw@sisk.pl> References: Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from ogre.sisk.pl ([193.178.161.156]:51784 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751908Ab2I2WY2 (ORCPT ); Sat, 29 Sep 2012 18:24:28 -0400 In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Stern Cc: Aaron Lu , Oliver Neukum , 'James Bottomley' , Jeff Garzik , linux-pm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org On Saturday, September 29, 2012, Alan Stern wrote: > On Sat, 29 Sep 2012, Aaron Lu wrote: > > > > I don't think this is a good idea, quite frankly. sr seems to be a too > > > generic place for that. > > > > Does this mean sr can only have code that is useful to all devices it > > manages? i.e. If a piece of code enables a feature for a special kind of > > ODD(like the sata based ZPODD), it shouldn't be done in sr? > > Drivers are allowed to have special features and quirks that apply only > to some devices. > > > There is nothing in theory stopping us from doing this in ata layer. > > For the loading mechanism, we can always send an ATAPI command to figure > > it out. > > > > So gentlemen, I need your opinions on where this ZPODD code should live > > before I can continue this work, thanks. > > Can arbitrary SCSI devices be ZP, or does this notion apply only to > ATAPI-based drives? That's the key question, and the answer determines > where the ZP support belongs. I agree. That said for now I'm not aware of any other ZP devices. It also is unclear whether or not their requirements would be the same for the ZPODD devices. > On the other hand, the sr driver certainly deserves to have some form > of runtime PM support, even for devices that aren't ZP. Yes, it does, but it is unclear to me at this point what it should do in its callbacks. Thanks, Rafael