From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] libata: Add ALPM power state accounting to the AHCI driver Date: Mon, 16 Nov 2009 03:13:48 -0500 Message-ID: <4B0109BC.1020204@pobox.com> References: <20091113192429.4dfc9c39@infradead.org> <4AFFB65F.3020201@kernel.org> <4AFFBB75.7050601@pobox.com> <20091115094630.1785b5ca@infradead.org> <4B004328.8060807@kernel.org> <20091115102334.1396eea6@infradead.org> <4B0047CB.5080509@kernel.org> <20091115103313.4691924d@infradead.org> <4B00B034.5010908@kernel.org> <20091115180058.55caa36f@infradead.org> <4B00B5D0.4010707@kernel.org> <20091115215531.23edcf5e@infradead.org> <4B00EDAC.4080904@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:35363 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751175AbZKPIN6 (ORCPT ); Mon, 16 Nov 2009 03:13:58 -0500 In-Reply-To: <4B00EDAC.4080904@kernel.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: Arjan van de Ven , linux-ide@vger.kernel.org, akpm@linux-foundation.org On 11/16/2009 01:14 AM, Tejun Heo wrote: > Hello, > > Arjan van de Ven wrote: >> sigh. so I moved all the generic logic generic, and left the ahci >> specific code specific to ahci. I put the logic there where it was >> easy to implement, and there where the other link power management >> controls are (in sysfs). If that's not good enough, I'm out of my skills >> in the libata world to be honest, and would like to ask you to implement >> that instead. let me know what sysfs looks like and I'll adjust >> powertop to it.... > > The reason why we have sysfs attributes which should have been at link > layer at host was that it originally was for ahci alpm which is host > specific feature which got extended to something somewhat generic. > Now another pm feature which should belong to link is added to host > following the precedence. > > Then again, it's also true that nobody really cares about ATA PM > features enough during past couple of years so I really don't want to > prevent the feature you're trying to add. It would be best if there's > someone who would pick it up and implement proper infrastructure but > well that doesn't seem to be happening anytime soon. > > So, I don't know. That's the concern I have but I don't want to nack > your change either. One thing is at least make those functions take > ata_link isntead of ata_port as there's nothing port specific about > those. Jeff, what do you think? Well, - these are link-level features - libata lacks a link-level sysfs API - we need a link-level sysfs API (ata_transport, anyone?) The ugly alternative has always been to hack in something at the host level. In term of internal data structures, the v3 patch putting the stats into struct ata_link is definitely the right thing to do. I would also put the accounting_enabled variable in there, as non-AHCI implementations, polling or not, seem highly likely to need that. Jeff