From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Subject: Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". Date: Wed, 12 Oct 2016 17:28:38 +0300 Message-ID: <877f9dd4kp.fsf@intel.com> References: <87h98ktxow.fsf@intel.com> <87lgxvqlg3.fsf@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by gabe.freedesktop.org (Postfix) with ESMTPS id EFD1A6E3DE for ; Wed, 12 Oct 2016 14:28:46 +0000 (UTC) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Emil Velikov Cc: "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "Sun, Jing A" , "Vetter, Daniel" , Thierry Reding List-Id: dri-devel@lists.freedesktop.org T24gV2VkLCAxMiBPY3QgMjAxNiwgRW1pbCBWZWxpa292IDxlbWlsLmwudmVsaWtvdkBnbWFpbC5j b20+IHdyb3RlOgo+IE9uIDExIE9jdG9iZXIgMjAxNiBhdCAxMDozMywgSmFuaSBOaWt1bGEgPGph bmkubmlrdWxhQGxpbnV4LmludGVsLmNvbT4gd3JvdGU6Cj4+IE9uIFR1ZSwgMTEgT2N0IDIwMTYs ICJTdW4sIEppbmcgQSIgPGppbmcuYS5zdW5AaW50ZWwuY29tPiB3cm90ZToKPj4+IEl0J3MgbmVl ZGVkIHRoYXQgRFJNIERyaXZlciBtb2R1bGUgY291bGQgYmUgcmVtb3ZlZCBhbmQgcmVsb2FkZWQg YWZ0ZXIKPj4+IGtlcm5lbCBib290aW5nIG9uIHRoZSBwcm9qZWN0cyB0aGF0IEkgaGF2ZSBiZWVu IHdvcmtpbmcgb24sIGFuZCBJIGhvcGUKPj4+IHN1Y2ggbW9kdWxlIHR5cGUgY2hhbmdlIGNvdWxk IGJlIGFjY2VwdGVkLiBMb29rcyBsaWtlIEl3YWkgaGFzIHNpbWlsYXIKPj4+IGNoYW5nZSByZXF1 ZXN0IGFzIHdlbGwuIFdvdWxkIHlvdSBwbGVhc2UgcmV2aWV3IGl0IGFuZCBsZXQgdXMga25vdyBp Zgo+Pj4gYW55IGNvbmNlcm5zPwo+Pgo+PiBMb29raW5nIGF0IHRoZSBLY29uZmlnLCBzZWxlY3Rp bmcgQ09ORklHX0RSTV9NSVBJX0RTSSBpcyBhZ2FpbnN0IHRoZQo+PiByZWNvbW1lbmRhdGlvbnMg b2YgRG9jdW1lbnRhdGlvbi9rYnVpbGQva2NvbmZpZy1sYW5ndWFnZS50eHQ6Cj4+Cj4+ICAgICAg ICAgc2VsZWN0IHNob3VsZCBiZSB1c2VkIHdpdGggY2FyZS4gc2VsZWN0IHdpbGwgZm9yY2UKPj4g ICAgICAgICBhIHN5bWJvbCB0byBhIHZhbHVlIHdpdGhvdXQgdmlzaXRpbmcgdGhlIGRlcGVuZGVu Y2llcy4KPj4gICAgICAgICBCeSBhYnVzaW5nIHNlbGVjdCB5b3UgYXJlIGFibGUgdG8gc2VsZWN0 IGEgc3ltYm9sIEZPTyBldmVuCj4+ICAgICAgICAgaWYgRk9PIGRlcGVuZHMgb24gQkFSIHRoYXQg aXMgbm90IHNldC4KPj4gICAgICAgICBJbiBnZW5lcmFsIHVzZSBzZWxlY3Qgb25seSBmb3Igbm9u LXZpc2libGUgc3ltYm9scwo+PiAgICAgICAgIChubyBwcm9tcHRzIGFueXdoZXJlKSBhbmQgZm9y IHN5bWJvbHMgd2l0aCBubyBkZXBlbmRlbmNpZXMuCj4+ICAgICAgICAgVGhhdCB3aWxsIGxpbWl0 IHRoZSB1c2VmdWxuZXNzIGJ1dCBvbiB0aGUgb3RoZXIgaGFuZCBhdm9pZAo+PiAgICAgICAgIHRo ZSBpbGxlZ2FsIGNvbmZpZ3VyYXRpb25zIGFsbCBvdmVyLgo+Pgo+PiBJbmRlZWQsIHlvdSBtYXkg ZW5kIHVwIHdpdGggQ09ORklHX0RSTV9NSVBJX0RTST15IGFuZCBDT05GSUdfRFJNPW0sCj4+IHdo aWNoIHZpb2xhdGVzIERSTV9NSVBJX0RTSSBkZXBlbmRlbmN5IG9uIENPTkZJR19EUk0uIFRoaXMg aXMgYnJva2VuIGFuZAo+PiBzaG91bGQgYmUgZml4ZWQuIFRoZSBzdWdnZXN0ZWQgcGF0Y2ggZG9l cyAqbm90KiBmaXggdGhpcyBpc3N1ZS4KPj4KPiBKYW5pLCBnaXQgbG9nIHN1Z2dlc3RzIHlvdSBh cyB0aGUgdW5mb3J0dW5hdGUgYXV0aG9yIG9mIHRoZSBzZWxlY3QKPiBEUk1fTUlQSV9EU0kvc2Vs ZWN0IERSTV9QQU5FTCBodW5rcyBpbiBpOTE1IDstKQoKL29cCgpBcyBtdWNoIGFzIG15IHByZXNl bnQgc2VsZiB3b3VsZCBsaWtlIHRvIHNjb2xkIG15IHBhc3Qgc2VsZiBmb3IgYWxsIGhpcwptaXN0 YWtlcywgSSBoYXZlIHRvIHJlbWluZCBteXNlbGYgdGhhdCBpdCBpcyB0aGUgbWlzdGFrZXMgdGhh dCBoYXZlCmdpdmVuIG1lIGludmFsdWFibGUgZXhwZXJpZW5jZSB0aGF0IG15IHBhc3Qgc2VsZiBk aWRuJ3QgaGF2ZS4gSSBjYW4gb25seQpob3BlIG15IGZ1dHVyZSBzZWxmIHdpbGwgaGF2ZSB0aW1l IHRvIGZpeCBldmVuIGEgZnJhY3Rpb24gb2YgdGhlCm1pc3Rha2VzLgoKQW55d2F5LCBhcyBBbmRy emVqIHBvaW50ZWQgb3V0LCBhbGwgY29uZmlncyB0aGF0IHNlbGVjdCBEUk1fTUlQSV9EU0kKYWxz byBkZXBlbmQgb24gRFJNLCBzbyB0aGlzIHByb2JsZW0gY2FuJ3QgY3VycmVudGx5IG9jY3VyLiBP bmNlIGRzaSBidXMKdW4tcmVnaXN0cmF0aW9uIGdldHMgYWRkcmVzc2VkLCB3ZSBjYW4gdHVybiBE Uk1fTUlQSV9EU0kgaW50byBhIHRyaXN0YXRlCmNvbmZpZyAoaS5lLiBhIGxvYWRhYmxlIG1vZHVs ZSkuCgpCUiwKSmFuaS4KCi0tIApKYW5pIE5pa3VsYSwgSW50ZWwgT3BlbiBTb3VyY2UgVGVjaG5v bG9neSBDZW50ZXIKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X18KZHJpLWRldmVsIG1haWxpbmcgbGlzdApkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0b3Aub3Jn Cmh0dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vZHJpLWRldmVs Cg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933512AbcJLO2y (ORCPT ); Wed, 12 Oct 2016 10:28:54 -0400 Received: from mga09.intel.com ([134.134.136.24]:35948 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932751AbcJLO2r (ORCPT ); Wed, 12 Oct 2016 10:28:47 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,482,1473145200"; d="scan'208";a="771777253" From: Jani Nikula To: Emil Velikov Cc: "Sun\, Jing A" , Takashi Iwai , "airlied\@linux.ie" , "Vetter\, Daniel" , "linux-kernel\@vger.kernel.org" , "dri-devel\@lists.freedesktop.org" , "a.hajda\@samsung.com" , Thierry Reding Subject: Re: [PATCH]"drm: change DRM_MIPI_DSI module type from "bool" to "tristate". In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <87h98ktxow.fsf@intel.com> <87lgxvqlg3.fsf@intel.com> Date: Wed, 12 Oct 2016 17:28:38 +0300 Message-ID: <877f9dd4kp.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 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). BR, Jani. -- Jani Nikula, Intel Open Source Technology Center