From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] libata: Add ALPM power state accounting to the AHCI driver Date: Tue, 17 Nov 2009 01:25:15 +0900 Message-ID: <4B017CEB.7050309@kernel.org> 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> <4B0109BC.1020204@pobox.com> <20091116064308.741b9a5b@infradead.org> <4B0168DB.50109@kernel.org> <20091116072114.65c6fbc2@infradead.org> <4B017133.3060209@kernel.org> <20091116155734.13912158@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from hera.kernel.org ([140.211.167.34]:40438 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751827AbZKPQ0S (ORCPT ); Mon, 16 Nov 2009 11:26:18 -0500 In-Reply-To: <20091116155734.13912158@lxorguk.ukuu.org.uk> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Cox Cc: Arjan van de Ven , Jeff Garzik , linux-ide@vger.kernel.org, akpm@linux-foundation.org Alan Cox wrote: >> This is true for all link functions, so I'm suggesting the stats >> helpers to follow the same convention. This will also make slave link >> configuration work properly (controllers which present two SATA links >> as master/slave of the same port but still provide access to separate >> SCR registers). You know, it's a link function, make it take a link >> as all other stuff is designed that way. > > I don't see how you can do per link reporting on AHCI. > > Sure maybe some devices should expose it per link, but it's so expensive > and it'll get really ugly fast. Not for ahci but ata_piix, sis and via already do it. > I'd say it has to go in at host level for now. If some super whizzo > future silicon exposes it per link without being beaten around the head > by the software stack then it's easy enough to add per link data and a > generic helper which provides a summary set of numbers at the host level > for hardware that can report link data. > > That gives us a useful API now and the ability to fix it in the future, > not that I anticipate anyone ever needing to. AHCI (or AHCI-ish) seems to > be what everyone is working to nowdays with little obvious pressure to > move anywhere else. Yeap, agreed. It just is so ugly (not Arjan's fault). Thanks. -- tejun