From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 2310EDE015 for ; Thu, 28 May 2009 05:05:55 +1000 (EST) Message-Id: <92B9A919-0F13-43FA-8E01-4470065A9131@kernel.crashing.org> From: Becky Bruce To: FUJITA Tomonori In-Reply-To: <20090522194930E.fujita.tomonori@lab.ntt.co.jp> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Mime-Version: 1.0 (Apple Message framework v930.3) Subject: Re: [PATCH V2 2/3] powerpc: Add support for swiotlb on 32-bit Date: Wed, 27 May 2009 14:05:42 -0500 References: <4A1592CF.8000208@goop.org> <4A15B72E.2070202@goop.org> <20090522194930E.fujita.tomonori@lab.ntt.co.jp> Cc: linuxppc-dev@ozlabs.org, jeremy@goop.org, linux-kernel@vger.kernel.org, Ian.Campbell@citrix.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On May 22, 2009, at 5:51 AM, FUJITA Tomonori wrote: > On Thu, 21 May 2009 13:18:54 -0700 > Jeremy Fitzhardinge wrote: > >> Becky Bruce wrote: >>> I can work with that, but it's going to be a bit inefficient, as I >>> actually need the dma_addr_t, not the phys_addr_t, so I'll have to >>> convert. In every case, this is a conversion I've already done and >>> that I need in the calling code as well. Can we pass in both the >>> phys_addr_t and the dma_addr_t? >> >> The Xen implementation would needs to do the phys to bus conversion >> page >> by page anyway, so it wouldn't help much. But it also wouldn't hurt. >> >> How expensive is the phys-to-bus conversion on power? Is it worth >> making the interface more complex for? Would passing phys+bus mean >> that >> we wouldn't also need to pass dev? > > I don't think so. POWERPC needs it. Hrm, it looks like my response to this got dropped. Fujita is correct - we still need the dev on powerpc because we use it to get device- specific information that is used to determining when we need to actually bounce. Cheers, B