From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752734AbcELJYI (ORCPT ); Thu, 12 May 2016 05:24:08 -0400 Received: from foss.arm.com ([217.140.101.70]:57077 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752341AbcELJYG (ORCPT ); Thu, 12 May 2016 05:24:06 -0400 Subject: Re: [PATCH] drm: mediatek: remove IOMMU_DMA select To: Arnd Bergmann , airlied@redhat.com, David Airlie References: <1462982509-342936-1-git-send-email-arnd@arndb.de> <1462997501-982363-1-git-send-email-arnd@arndb.de> Cc: Bibby Hsieh , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Mao Huang , YT Shen , CK Hu , linux-mediatek@lists.infradead.org, Philipp Zabel , Matthias Brugger , linux-arm-kernel@lists.infradead.org From: Robin Murphy Message-ID: <57344BB2.8020608@arm.com> Date: Thu, 12 May 2016 10:24:02 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <1462997501-982363-1-git-send-email-arnd@arndb.de> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/05/16 21:11, Arnd Bergmann wrote: > We get a harmless build warning when trying to use the mediatek > DRM driver with IOMMU support disabled: > > warning: (DRM_MEDIATEK) selects IOMMU_DMA which has unmet direct dependencies (IOMMU_SUPPORT) > > However, the IOMMU_DMA symbol is not meant to be used by drivers > at all, and this driver doesn't seem to have a strict dependency > on it other than using the mediatek IOMMU driver that does. > > Since we also want to be able to do compile tests with the > driver on other platforms, the IOMMU_DMA symbol should not > be selected here. > > Signed-off-by: Arnd Bergmann > --- > If someone has a better explanation about why the 'select' is here, > let me know, it certainly seems out of place. Ack - it's neither an IOMMU driver nor a DMA API implementation, so it has no business with IOMMU_DMA. If there's an IOMMU dependency in general it should be on MTK_IOMMU, not underlying implementation details. Robin. > drivers/gpu/drm/mediatek/Kconfig | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/gpu/drm/mediatek/Kconfig b/drivers/gpu/drm/mediatek/Kconfig > index 0c06a69d7f04..545973f6b743 100644 > --- a/drivers/gpu/drm/mediatek/Kconfig > +++ b/drivers/gpu/drm/mediatek/Kconfig > @@ -7,7 +7,6 @@ config DRM_MEDIATEK > select DRM_KMS_HELPER > select DRM_MIPI_DSI > select DRM_PANEL > - select IOMMU_DMA > select MEMORY > select MTK_SMI > help >