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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 B1B4AC4360D for ; Wed, 25 Sep 2019 21:26:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 86D412054F for ; Wed, 25 Sep 2019 21:26:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="p2r1071H" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726303AbfIYV0n (ORCPT ); Wed, 25 Sep 2019 17:26:43 -0400 Received: from lelv0143.ext.ti.com ([198.47.23.248]:57310 "EHLO lelv0143.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726139AbfIYV0n (ORCPT ); Wed, 25 Sep 2019 17:26:43 -0400 Received: from fllv0035.itg.ti.com ([10.64.41.0]) by lelv0143.ext.ti.com (8.15.2/8.15.2) with ESMTP id x8PLQTJJ089587; Wed, 25 Sep 2019 16:26:29 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1569446789; bh=L31cUsQNSVbjLWHHKpLMzPbfxz4gfU8gEYEWZo7VRD4=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=p2r1071HZ9y8EGc8xiGpOsXeJy2yAEfOjLCL17cM0ykGWc8amevRRcsEDHaD7tfOI oU33SWp5+ZQOxSUIiJD3iBh2zdw1XS5il1t2emezEn4wE+FuZS7E7VR5IjnQbT6+7L L3VWeUcY49QtSuA7Qe3S7H6av7k/UR5+rG+P/TxQ= Received: from DLEE100.ent.ti.com (dlee100.ent.ti.com [157.170.170.30]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTP id x8PLQTGV030025; Wed, 25 Sep 2019 16:26:29 -0500 Received: from DLEE111.ent.ti.com (157.170.170.22) by DLEE100.ent.ti.com (157.170.170.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5; Wed, 25 Sep 2019 16:26:29 -0500 Received: from fllv0039.itg.ti.com (10.64.41.19) by DLEE111.ent.ti.com (157.170.170.22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5 via Frontend Transport; Wed, 25 Sep 2019 16:26:22 -0500 Received: from [10.250.197.29] (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id x8PLQRXj125159; Wed, 25 Sep 2019 16:26:28 -0500 Subject: Re: [PATCH] drm/omap: Migrate minimum FCK/PCK ratio from Kconfig to dts To: Tomi Valkeinen , Adam Ford , CC: Mark Rutland , , David Airlie , , , Tony Lindgren , Rob Herring , =?UTF-8?Q?Beno=c3=aet_Cousson?= , References: <20190510194229.20628-1-aford173@gmail.com> From: "Andrew F. Davis" Message-ID: <93c141c6-6519-4855-2424-f7b348b5df25@ti.com> Date: Wed, 25 Sep 2019 14:26:27 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/28/19 4:11 AM, Tomi Valkeinen wrote: > Hi, > > On 10/05/2019 22:42, Adam Ford wrote: >> Currently the source code is compiled using hard-coded values >> from CONFIG_OMAP2_DSS_MIN_FCK_PER_PCK.  This patch allows this >> clock divider value to be moved to the device tree and be changed >> without having to recompile the kernel. >> >> Signed-off-by: Adam Ford > > I understand why you want to do this, but I'm not sure it's a good idea. > It's really something the driver should figure out, and if we add it to > the DT, it effectively becomes an ABI. > > That said... I'm not sure how good of a job the driver could ever do, as > it can't know the future scaling needs of the userspace at the time it > is configuring the clock. And so, I'm not nacking this patch, but I > don't feel very good about this patch... > > The setting also affects all outputs (exluding venc), which may not be > what the user wants. Then again, I think this setting is really only > needed on OMAP2 & 3, which have only a single output. But that's the > same with the current kconfig option, of course. > > So, the current CONFIG_OMAP2_DSS_MIN_FCK_PER_PCK is an ugly hack, in my > opinion, and moving it to DT makes it a worse hack =). But I don't have > any good suggestions either. > Module param? Andrew >  Tomi >