From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EAA1C2BB55 for ; Thu, 16 Apr 2020 15:18:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F81A214D8 for ; Thu, 16 Apr 2020 15:18:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="KunL1GHn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2504098AbgDPPSQ (ORCPT ); Thu, 16 Apr 2020 11:18:16 -0400 Received: from perceval.ideasonboard.com ([213.167.242.64]:42002 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2442384AbgDPPSH (ORCPT ); Thu, 16 Apr 2020 11:18:07 -0400 Received: from pendragon.ideasonboard.com (81-175-216-236.bb.dnainternet.fi [81.175.216.236]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 20E5497D; Thu, 16 Apr 2020 17:18:03 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1587050283; bh=kRV0TK76jaLsKumnRx9oBxQ+fB9EZ/hBhcVvcCrUN8Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KunL1GHnZWE+ve/sOLaoFkAzYPKX6+/n+r78iuYJs7x5e+okkGATOqE6ApGMnuikF /2ayUcQFN/Z9UdwuSHJbBCZB/V8aA1w7KUzO09ROtISEFr9rEn/3j6xTfoHtnx7/rk eGxptalaFyRgrldUK2vtce1M8FhIp7rddugLnmJg= Date: Thu, 16 Apr 2020 18:17:51 +0300 From: Laurent Pinchart To: Daniel Vetter Cc: Arnd Bergmann , Geert Uytterhoeven , "linux-kernel@vger.kernel.org" , Masahiro Yamada , Nicolas Pitre , Andrzej Hajda , Neil Armstrong , Jonas Karlman , Jernej Skrabec , David Airlie , Kieran Bingham , "David S. Miller" , Saeed Mahameed , Leon Romanovsky , dri-devel , Linux-Renesas , Networking , linux-rdma Subject: Re: [RFC 5/6] drm/rcar-du: fix selection of CMM driver Message-ID: <20200416151751.GD4796@pendragon.ideasonboard.com> References: <20200414201739.GJ19819@pendragon.ideasonboard.com> <20200414205158.GM19819@pendragon.ideasonboard.com> <20200415211220.GQ4758@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Apr 16, 2020 at 08:51:14AM +0200, Daniel Vetter wrote: > On Wed, Apr 15, 2020 at 11:22 PM Arnd Bergmann wrote: > > On Wed, Apr 15, 2020 at 11:12 PM Laurent Pinchart wrote: > > > On Wed, Apr 15, 2020 at 09:07:14PM +0200, Arnd Bergmann wrote: > > > > On Wed, Apr 15, 2020 at 5:18 PM Arnd Bergmann wrote: > > > > > On Wed, Apr 15, 2020 at 4:13 PM Geert Uytterhoeven wrote: > > > > > > On Wed, Apr 15, 2020 at 3:47 PM Arnd Bergmann wrote: > > > > > > > On Tue, Apr 14, 2020 at 10:52 PM Laurent Pinchart wrote: > > > > > > > > Doesn't "imply" mean it gets selected by default but can be manually > > > > > > > > disabled ? > > > > > > > > > > > > > > That may be what it means now (I still don't understand how it's defined > > > > > > > as of v5.7-rc1), but traditionally it was more like a 'select if all > > > > > > > dependencies are met'. > > > > > > > > > > > > That's still what it is supposed to mean right now ;-) > > > > > > Except that now it should correctly handle the modular case, too. > > > > > > > > > > Then there is a bug. If I run 'make menuconfig' now on a mainline kernel > > > > > and enable CONFIG_DRM_RCAR_DU, I can set > > > > > DRM_RCAR_CMM and DRM_RCAR_LVDS to 'y', 'n' or 'm' regardless > > > > > of whether CONFIG_DRM_RCAR_DU is 'm' or 'y'. The 'implies' > > > > > statement seems to be ignored entirely, except as reverse 'default' > > > > > setting. > > > > > > > > Here is another version that should do what we want and is only > > > > half-ugly. I can send that as a proper patch if it passes my testing > > > > and nobody hates it too much. > > > > > > This may be a stupid question, but doesn't this really call for fixing > > > Kconfig ? This seems to be such a common pattern that requiring > > > constructs similar to the ones below will be a never-ending chase of > > > offenders. > > > > Maybe, I suppose the hardest part here would be to come up with > > an appropriate name for the keyword ;-) > > > > Any suggestions? Would it make sense to fix the imply semantics ? Or are they use cases for the current behaviour of imply ? "recommend" could be another keyword. I think we should try to limit the number of keywords though, as it would otherwise become quite messy. > > This specific issue is fairly rare though, in most cases the dependencies > > are in the right order so a Kconfig symbol 'depends on' a second one > > when the corresponding loadable module uses symbols from that second > > module. The problem here is that the two are mixed up. > > > > The much more common problem is the one where one needs to > > wrong > > > > config FOO > > depends on BAR || !BAR > > > > To ensure the dependency is either met or BAR is disabled, but > > not FOO=y with BAR=m. If you have any suggestions for a keyword > > for that thing, we can clean up hundreds of such instances. > > Some ideas: > > config FOO > can use BAR > maybe BAR > optional BAR Another idea, depends optionally on BAR > We should probably double-check that this is only ever used for when > both FOO and BAR are tri-state, since without that it doesn't make > much sense. -- Regards, Laurent Pinchart