From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752968Ab1IVNsc (ORCPT ); Thu, 22 Sep 2011 09:48:32 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:52575 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751059Ab1IVNs3 (ORCPT ); Thu, 22 Sep 2011 09:48:29 -0400 MIME-Version: 1.0 In-Reply-To: <201109201254.39542.laurent.pinchart@ideasonboard.com> References: <1316009259-18052-1-git-send-email-joerg.roedel@amd.com> <201109180202.23123.laurent.pinchart@ideasonboard.com> <20110920100146.GA2078@amd.com> <201109201254.39542.laurent.pinchart@ideasonboard.com> Date: Thu, 22 Sep 2011 16:48:27 +0300 Message-ID: Subject: Re: [PATCH] iommu/omap: Fix build error with !IOMMU_SUPPORT From: Felipe Contreras To: Laurent Pinchart Cc: "Roedel, Joerg" , "linux-omap@vger.kernel.org" , Ohad Ben-Cohen , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 20, 2011 at 1:54 PM, Laurent Pinchart wrote: > On Tuesday 20 September 2011 12:01:46 Roedel, Joerg wrote: >> On Sat, Sep 17, 2011 at 08:02:22PM -0400, Laurent Pinchart wrote: >> > On Wednesday 14 September 2011 16:07:39 Joerg Roedel wrote: >> > > Without this patch it is possible to select the VIDEO_OMAP3 >> > > driver which then selects OMAP_IOVMM. But the omap iommu >> > > driver is not compiled without IOMMU_SUPPORT enabled. Fix >> > > that by forcing OMAP_IOMMU and OMAP_IOVMM are enabled before >> > > VIDEO_OMAP3 can be selected. >> > >> > What about making VIDEO_OMAP3 select IOMMU_SUPPORT instead then ? Your >> > patch would make the OMAP3 ISP driver disappear from the menu until >> > IOMMU_SUPPORT gets turned on, which can confuse users. >> >> Using 'depends on' rather then 'selects' is common standard in Kconfig. >> You can't select PCI drivers without selecting PCI first, for example. > > You wouldn't expect a PCI driver to work without PCI support. My concern is > that most OMAP3 ISP users won't know that IOMMU supports is required. Feel > free to ignore it though :-) I agree with Laurent. As a user, why should I care about IOMMU? I just want this thing. That's why DRM_RADEON_KMS selects BACKLIGHT_CLASS_DEVICE; it's an implementation detail that the user should not need to care about. Why should I need to go see the dependencies of DRM_RADEON_KMS and manually select all of them? I shouldn't, that's the reason 'select' exists in the first place. Cheers. -- Felipe Contreras