From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx200.postini.com [74.125.245.200]) by kanga.kvack.org (Postfix) with SMTP id 10B516B004F for ; Fri, 9 Dec 2011 09:23:40 -0500 (EST) Date: Fri, 9 Dec 2011 14:24:05 +0000 From: Alan Cox Subject: Re: [Linaro-mm-sig] [RFC v2 1/2] dma-buf: Introduce dma buffer sharing mechanism Message-ID: <20111209142405.6f371be6@pyramind.ukuu.org.uk> In-Reply-To: <201112091413.03736.arnd@arndb.de> References: <1322816252-19955-1-git-send-email-sumit.semwal@ti.com> <201112071340.35267.arnd@arndb.de> <201112091413.03736.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Arnd Bergmann Cc: Daniel Vetter , "Semwal, Sumit" , linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org > I still don't think that's possible. Please explain how you expect > to change the semantics of the streaming mapping API to allow multiple > mappers without having explicit serialization points that are visible > to all users. For simplicity, let's assume a cache coherent system I would agree. It's not just about barriers but in many cases where you have multiple mappings by hardware devices the actual hardware interface is specific to the devices. Just take a look at the fencing in TTM and the graphics drivers. Its not something the low level API can deal with, it requires high level knowledge. Alan -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org