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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 65C94C5B57D for ; Fri, 5 Jul 2019 09:16:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45A9D2147A for ; Fri, 5 Jul 2019 09:16:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728062AbfGEJQm (ORCPT ); Fri, 5 Jul 2019 05:16:42 -0400 Received: from mga09.intel.com ([134.134.136.24]:16234 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727632AbfGEJQm (ORCPT ); Fri, 5 Jul 2019 05:16:42 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Jul 2019 02:16:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,454,1557212400"; d="scan'208";a="363551708" Received: from paasikivi.fi.intel.com ([10.237.72.42]) by fmsmga006.fm.intel.com with ESMTP; 05 Jul 2019 02:16:38 -0700 Received: by paasikivi.fi.intel.com (Postfix, from userid 1000) id 07C2820904; Fri, 5 Jul 2019 12:16:37 +0300 (EEST) Date: Fri, 5 Jul 2019 12:16:37 +0300 From: Sakari Ailus To: Laurent Pinchart Cc: Hugues FRUCHET , Hans Verkuil , Alexandre TORGUE , Mauro Carvalho Chehab , "linux-media@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-stm32@st-md-mailman.stormreply.com" , Benjamin Gaignard , Yannick FERTRE , Philippe CORNU , Mickael GUENE Subject: Re: [PATCH v2 0/3] DCMI bridge support Message-ID: <20190705091637.b5626yvkycumsp6z@paasikivi.fi.intel.com> References: <1560242912-17138-1-git-send-email-hugues.fruchet@st.com> <20190620161721.h3wn4nibomrvriw4@kekkonen.localdomain> <20190626172503.GB6118@pendragon.ideasonboard.com> <20190627133824.GC5021@pendragon.ideasonboard.com> <20190705075522.o7kuptdy3p3o64l7@paasikivi.fi.intel.com> <20190705080424.GA4994@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190705080424.GA4994@pendragon.ideasonboard.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Laurent, On Fri, Jul 05, 2019 at 11:04:24AM +0300, Laurent Pinchart wrote: ... > > A reasonable compromise would be to add a Kconfig option that allows > > enabling MC. This way you can provide backwards compatibility and allow > > making use of the full potential of the hardware. That's also why hardware > > that may be part of a non-trivial MC pipeline should start with MC-enabled > > so we wouldn't run into this. > > I really don't like this, as it introduces additional complexity. My > recommendation is to go for an MC-centric approach. Going for a video > node-centric approach is really shooting oneself in the foot regarding > future extensions. But that being said, if there's a strong desire to go > for foot self-shooting, the way to go is explained above. Well, there's nothing that can be done anymore as this has already happened: this is an existing driver in the mainline kernel. Unless you have a time machine of some sort, of course. :-) The choice is now really between breaking existing applications (plain V4L2) and supporting new functionality (MC-centric), so if you need both, I don't really see another choice than a Kconfig option. On the other hand, if we know there are no existing users that could not support the MC-centric view of the device, we could just change the driver API and forget the Kconfig option. It'd be much more simple that way indeed. But I don'k know what's the case. -- Regards, Sakari Ailus sakari.ailus@linux.intel.com