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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 C13C2C55199 for ; Mon, 27 Apr 2020 11:37:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A004F206B6 for ; Mon, 27 Apr 2020 11:37:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="Rg7KBMJn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727055AbgD0Lhq (ORCPT ); Mon, 27 Apr 2020 07:37:46 -0400 Received: from lelv0142.ext.ti.com ([198.47.23.249]:53696 "EHLO lelv0142.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726260AbgD0Lhp (ORCPT ); Mon, 27 Apr 2020 07:37:45 -0400 Received: from lelv0265.itg.ti.com ([10.180.67.224]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id 03RBbebG012356; Mon, 27 Apr 2020 06:37:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1587987460; bh=5QDEIBRwUNoI7dvYP0AT0ZGIXfUe6VQAiR6ihBCjn1A=; h=Subject:From:To:References:Date:In-Reply-To; b=Rg7KBMJneKFflF9BjjsRobXIHl3wXsOrehZue6ezyqGROjtpT5Uyt9E5ZTg++0YmX OU0CburW2v8RNRugJI8rmL6aCDEkDPlBum9JzoNqdNkPZ+6FNI6niYvQkSShsJQLKo Ot+yYoJL07fqlC1n3dxHbY5VCPFw+QTMfZxrBUNw= Received: from DLEE108.ent.ti.com (dlee108.ent.ti.com [157.170.170.38]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 03RBbeGq021143 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 27 Apr 2020 06:37:40 -0500 Received: from DLEE110.ent.ti.com (157.170.170.21) by DLEE108.ent.ti.com (157.170.170.38) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3; Mon, 27 Apr 2020 06:37:39 -0500 Received: from lelv0326.itg.ti.com (10.180.67.84) by DLEE110.ent.ti.com (157.170.170.21) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1979.3 via Frontend Transport; Mon, 27 Apr 2020 06:37:39 -0500 Received: from [192.168.2.6] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0326.itg.ti.com (8.15.2/8.15.2) with ESMTP id 03RBbblB052342; Mon, 27 Apr 2020 06:37:38 -0500 Subject: Re: [PATCH 2/3] arm64: dts: ti: k3-j721e-main.dtsi: Add DSS node From: Tomi Valkeinen To: Jyri Sarha , Tero Kristo , Nishanth Menon , Rob Herring , , , References: <20200422091512.950-1-tomi.valkeinen@ti.com> <20200422091512.950-2-tomi.valkeinen@ti.com> <47b7f858-a8d9-1c3b-4dca-2cc493f6730f@ti.com> <217c0c14-f4fb-7321-9f57-205df0cd01fe@ti.com> <9a4b1d0a-c871-2280-8d22-196730e9385b@ti.com> Message-ID: <3eb05f6d-523f-f7e5-a0e9-d47b852fe079@ti.com> Date: Mon, 27 Apr 2020 14:37:37 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <9a4b1d0a-c871-2280-8d22-196730e9385b@ti.com> Content-Type: text/plain; charset="utf-8"; format=flowed 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 27/04/2020 14:15, Tomi Valkeinen wrote: > On 27/04/2020 14:10, Jyri Sarha wrote: >> On 27/04/2020 13:51, Tomi Valkeinen wrote: >>> On 27/04/2020 13:37, Jyri Sarha wrote: >>>> On 27/04/2020 13:09, Tero Kristo wrote: >>>>>> +        status = "disabled"; >>>>> >>>>> Again, why disabled by default? >>>>> >>>> >>>> tidss device is not functional without a defined video-port. The driver >>>> is not implemented in a way that it would handle a broken configuration >>>> gracefully. >>> >>> Then we need to fix it. The driver should handle the case where there >>> are no ports defined just fine. >>> >> >> Just by reading the code, I would say that currently the probe would >> fail with returned -ENOMEM after calling drm_vblank_init() with zero CRTCs. >> >> So should the probe fail gracefully and silently, or should we try to >> register a DRM device with no CRTCs? Is that even possible? > > My first thought is that the driver should exit probe silently with ENODEV if there are no outputs > defined (but, of course, with EPROBE_DEFER if there are outputs which haven't been probed yet). > > It gets a bit more complex if we ever support writeback, as that can be used as mem-to-mem without > any displays, but I think we can ignore that for now. In any case, that's not the reason for status = "disabled", so that discussion is not related to these patches as such. The reason to have DSS disabled is just to prevent pointless driver probing. When a board dts or a DT overlay adds a display, the DSS DT node has to be modified anyway to add the DT graph and the panel/bridge data. So one can as well add the single line of "status = enabled" there. Tomi -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki