Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932647AbdC3IqM (ORCPT ); Thu, 30 Mar 2017 04:46:12 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:58688 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932503AbdC3IqB (ORCPT ); Thu, 30 Mar 2017 04:46:01 -0400 Date: Thu, 30 Mar 2017 01:45:55 -0700 From: Christoph Hellwig To: Boris Brezillon Cc: Max Filippov , Christoph Hellwig , Chris Zankel , "linux-xtensa@linux-xtensa.org" , Maxime Ripard , Thomas Petazzoni , LKML Subject: Re: [PATCH] xtensa: Fix mmap() support Message-ID: <20170330084555.GA13310@infradead.org> References: <1490689242-5097-1-git-send-email-boris.brezillon@free-electrons.com> <20170330103032.35558cf3@bbrezillon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170330103032.35558cf3@bbrezillon> User-Agent: Mutt/1.7.1 (2016-10-04) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 669 Lines: 11 On Thu, Mar 30, 2017 at 10:30:32AM +0200, Boris Brezillon wrote: > I think I misunderstood what CONFIG_ARCH_NO_COHERENT_DMA_MMAP means. > My understanding was that, if CONFIG_ARCH_NO_COHERENT_DMA_MMAP is not > set, the architecture is assumed to be cache-coherent, but re-reading > the option name I realize you're probably right. It just says that the architecture did not support dma_common_mmap at the point in time when I switched all architectures to use the common dma_ops or implementing the various dma calls. There is no inherent logic behind the symbol, and if the few remaining architectures could support it with a bit work the option could just go away.