Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757157AbcJTNo5 (ORCPT ); Thu, 20 Oct 2016 09:44:57 -0400 Received: from mga14.intel.com ([192.55.52.115]:49527 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755635AbcJTNoz (ORCPT ); Thu, 20 Oct 2016 09:44:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,371,1473145200"; d="scan'208";a="775043447" From: Jani Nikula To: Andrzej Hajda , Emil Velikov Cc: "Sun\, Jing A" , Takashi Iwai , "airlied\@linux.ie" , "Vetter\, Daniel" , "linux-kernel\@vger.kernel.org" , "dri-devel\@lists.freedesktop.org" , Thierry Reding Subject: Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". In-Reply-To: <34ef3414-952d-461f-bc3c-a47fadd1b69a@samsung.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <87h98ktxow.fsf@intel.com> <87lgxvqlg3.fsf@intel.com> <877f9dd4kp.fsf@intel.com> <34ef3414-952d-461f-bc3c-a47fadd1b69a@samsung.com> Date: Thu, 20 Oct 2016 16:44:49 +0300 Message-ID: <87k2d3qgmm.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2806 Lines: 73 On Thu, 20 Oct 2016, Andrzej Hajda wrote: > Hi Jani, > > Forgive me late response. > > On 12.10.2016 16:28, Jani Nikula wrote: >> On Wed, 12 Oct 2016, Emil Velikov wrote: >>> On 11 October 2016 at 10:33, Jani Nikula wrote: >>>> On Tue, 11 Oct 2016, "Sun, Jing A" wrote: >>>>> It's needed that DRM Driver module could be removed and reloaded after >>>>> kernel booting on the projects that I have been working on, and I hope >>>>> such module type change could be accepted. Looks like Iwai has similar >>>>> change request as well. Would you please review it and let us know if >>>>> any concerns? >>>> Looking at the Kconfig, selecting CONFIG_DRM_MIPI_DSI is against the >>>> recommendations of Documentation/kbuild/kconfig-language.txt: >>>> >>>> select should be used with care. select will force >>>> a symbol to a value without visiting the dependencies. >>>> By abusing select you are able to select a symbol FOO even >>>> if FOO depends on BAR that is not set. >>>> In general use select only for non-visible symbols >>>> (no prompts anywhere) and for symbols with no dependencies. >>>> That will limit the usefulness but on the other hand avoid >>>> the illegal configurations all over. >>>> >>>> Indeed, you may end up with CONFIG_DRM_MIPI_DSI=y and CONFIG_DRM=m, >>>> which violates DRM_MIPI_DSI dependency on CONFIG_DRM. This is broken and >>>> should be fixed. The suggested patch does *not* fix this issue. >>>> >>> Jani, git log suggests you as the unfortunate author of the select >>> DRM_MIPI_DSI/select DRM_PANEL hunks in i915 ;-) >> /o\ >> >> As much as my present self would like to scold my past self for all his >> mistakes, I have to remind myself that it is the mistakes that have >> given me invaluable experience that my past self didn't have. I can only >> hope my future self will have time to fix even a fraction of the >> mistakes. >> >> Anyway, as Andrzej pointed out, all configs that select DRM_MIPI_DSI >> also depend on DRM, so this problem can't currently occur. Once dsi bus >> un-registration gets addressed, we can turn DRM_MIPI_DSI into a tristate >> config (i.e. a loadable module). > > There is already patch adding bus unregistration [1]. It was published > together > with 'tristate' patch [2], both were created by Takashi few months ago. Right. So make that "Once dis bus un-registration gets merged upstream". ;) BR, Jani. > > [1]: > https://lists.freedesktop.org/archives/dri-devel/2016-August/114870.html > [2]: > https://lists.freedesktop.org/archives/dri-devel/2016-August/114497.html > > Regards > Andrzej > >> >> BR, >> Jani. >> > -- Jani Nikula, Intel Open Source Technology Center