Received: by 2002:a05:6358:9144:b0:117:f937:c515 with SMTP id r4csp153047rwr; Wed, 19 Apr 2023 19:41:25 -0700 (PDT) X-Google-Smtp-Source: AKy350ZhxYsJVVtrvGTxj5HWRoiOntjKYHNPZOb1CcF2VUTKYwTbzvB25FUcs+rgPfTfyiIDl79m X-Received: by 2002:a05:6a20:4412:b0:ef:4fa7:b1f1 with SMTP id ce18-20020a056a20441200b000ef4fa7b1f1mr279200pzb.0.1681958484810; Wed, 19 Apr 2023 19:41:24 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1681958484; cv=none; d=google.com; s=arc-20160816; b=hJHcxlutsU3XSecLHMMNSog/0+3nLcvZB7FbdKkNk8cDTkxfeL2W1wzc4IgDHxrqIU HmlDRZcRyDQQZFzYp7DqAmh0JGk+11Ng7oKqVIJg0uyRTonwZFUSXEJ4tvo3bNakpgII epy9Vj0wvmkUhYE6HSla0T3iTK7MfANvMaToizOKt23D4wAVMkZt5shlJ+/PQ5Qgix3G LeMSVbWzTHKstPZ0MUoczTfRm3j3XuhUiMeiP5M/r8wdCdxuIP/eFF2BogoD5mKPAVvq +jtGzOjHdswrWUJjxkxT3i0oE3pZTwxntr1rRJkJuQkHvSVNG+7XdOO3iCUVFUjgJ7ef gsjA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:cc:to:subject :message-id:date:from:in-reply-to:references:mime-version :dkim-signature; bh=5hCnIiv0UZoUyqA3j7om4LR5r+3eUZFma/siIy2qvxI=; b=K3gdpkWtvvNxNpRk7E9EWUqfd82hQvF0+2On0sKITauhodFA4UqWMGAsbv7GXboO+c QAPnnhGisA3yrEN6up+CewdVcvZlX1obmmsR4Dle3eMaoCQ3DgDwCIZEUB7oUwMKl62P xqiUVn8nhApPos58SGd3Mfrfse+PsK58KTrzhM0/rOOETLV6B/KW75KU911+yxBsocYC 4u4RmkICuvJfF+K9LBld7NtK8Rl4WR+vMw8jahL3IPXTNM2DH6hR75hQ1i/ft8b13v2a kiUfo4RXqn1bdgpItJkfoNsF7EN2fOP6+1j6M60LzCZVJVSwLjPaQbDVROfWKgMbzpG/ a6vA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=aHY0KqzY; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id h23-20020a63e157000000b0051344de5b95si284344pgk.428.2023.04.19.19.40.57; Wed, 19 Apr 2023 19:41:24 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20221208 header.b=aHY0KqzY; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232762AbjDTCYT (ORCPT + 99 others); Wed, 19 Apr 2023 22:24:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229767AbjDTCYS (ORCPT ); Wed, 19 Apr 2023 22:24:18 -0400 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D9A6448A; Wed, 19 Apr 2023 19:24:14 -0700 (PDT) Received: by mail-pf1-x431.google.com with SMTP id d2e1a72fcca58-63b62d2f729so476437b3a.1; Wed, 19 Apr 2023 19:24:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1681957454; x=1684549454; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=5hCnIiv0UZoUyqA3j7om4LR5r+3eUZFma/siIy2qvxI=; b=aHY0KqzYmBUMNi2SicP8NE4mewVj4KbcqsIdBEOZnX3xv6AbcZVdLJaMN/46ZG2byr rBxvGegBdnF3Blj7IULlxmIG7Vc3WSEf6BxpnZwgTSwm5BKMmNTladesWKF27zZEbwa1 2/069yWBd3mg4yjNl+d9e9NWhFp+40oZgCrJat2dufA7loHBzTGP7MZEEccaSghk9UNB QdRJWyYbYJMp0DMsz6nPSJSA6qCJqVd/sd/tHuSTY6mh0fdNp7D77VyWAz3HdyDGpgw/ MVZJFN+jnIfr2ZMz23p3AofUQ3GIbgveA3oSWQVTDDG8Ucl0RVwh3QnYcf1cgW4/5zAf pf4g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681957454; x=1684549454; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=5hCnIiv0UZoUyqA3j7om4LR5r+3eUZFma/siIy2qvxI=; b=GVf+oQFaY6dVbZ6G6pD54B55hRS7qyPREg6bf/4taRGUeIKE2VVsAGu0nnDNZkgrrD aAGzDOBizcdvazbaqx6bHVCGEK7183HWvboM1vDZ/5Wl5TwrcLQ2QqzGci4v0zb19n7E fWDQMbMay/QGK/YrzlOdSOWh9+KGJb2L06+XyFfkNVNOOQyVDHx0ZIy2x+X/oZHJGk9z IPhmbXv66BPXPoLL1h4BsvEz7ioV03usk3hwAx1Y1FhD2oWXauUlye7o6arn2foK7bLR NidWL0yI3g1OFhETNY0s103nuuxjmwSFLprj2IUaRAiCk+wiWhccCia7W7bSXPcdSMGq 6tag== X-Gm-Message-State: AAQBX9dsk+sISvE+Fu/LrzhqmqTYGs2EdGXpabgI6ITqa/JznjH2hmf1 zwHx7tWKYPhto3eSkkna+ZBzJIR7bIEXLZv4n7I= X-Received: by 2002:a17:90a:ad90:b0:247:bd63:c3af with SMTP id s16-20020a17090aad9000b00247bd63c3afmr181414pjq.8.1681957453496; Wed, 19 Apr 2023 19:24:13 -0700 (PDT) MIME-Version: 1.0 References: <20230415104104.5537-1-aford173@gmail.com> <20230415104104.5537-5-aford173@gmail.com> <807aa6c6-bbea-abcc-172d-17e22d1a3988@denx.de> <88e53197-2819-c068-eba6-a218a19d8d15@denx.de> In-Reply-To: From: Adam Ford Date: Wed, 19 Apr 2023 21:24:02 -0500 Message-ID: Subject: Re: [PATCH 5/6] drm: bridge: samsung-dsim: Support non-burst mode To: Marek Vasut Cc: dri-devel@lists.freedesktop.org, m.szyprowski@samsung.com, aford@beaconembedded.com, Rob Herring , Krzysztof Kozlowski , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , Inki Dae , Jagan Teki , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , David Airlie , Daniel Vetter , Frieder Schrempf , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Lucas Stach Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 17, 2023 at 6:23=E2=80=AFPM Marek Vasut wrote: > > On 4/18/23 00:24, Adam Ford wrote: > > On Mon, Apr 17, 2023 at 3:08=E2=80=AFPM Marek Vasut wro= te: > >> > >> On 4/17/23 13:57, Adam Ford wrote: > >>> On Sun, Apr 16, 2023 at 5:13=E2=80=AFPM Marek Vasut w= rote: > >>>> > >>>> On 4/15/23 12:41, Adam Ford wrote: > >>>>> The high-speed clock is hard-coded to the burst-clock > >>>>> frequency specified in the device tree. However, when > >>>>> using devices like certain bridge chips without burst mode > >>>>> and varying resolutions and refresh rates, it may be > >>>>> necessary to set the high-speed clock dynamically based > >>>>> on the desired pixel clock for the connected device. > >>>> > >>>> The link rate negotiation should happen internally between the neare= st > >>>> bridge and DSIM, so please add that to DRM core instead of hacking > >>>> around it by tweaking the HS clock again. > >>> > >>> I thought you tried to add something like this before and had some re= sistance. > >> > >> Yes, all my attempts were rejected by a single reviewer. I suspended m= y > >> efforts in that area for now. > >> > >>> The Pixel clock is set by the bridge already without any new code > >>> added to the DRM core.. I am just reading that value that's there, > >>> and setting the clock accordingly. I don't see how this is a hack. > >> > >> Assume you have a DSI-to-HDMI bridge attached to your DSIM bridge, it > >> operates in non-burst mode, like ADV7533 . How would you configure the > > > > I have an ADV7535 > > > >> HS clock rate for such a bridge in DT ? (hint: you cannot, because the > >> required clock comes from the EDID, which may not be available just ye= t) > > > > The whole idea is that you wouldn't want to or need to configure the > > clock speed in the device tree because it comes from the > > EDID->bridge->DSI. > > > > I've tested this configuration on imx8mm, imx8mn, and imx8mp and I can > > change the resolution and refresh rate on the fly and the DSI will > > automatically readjust accordingly. If you fixed the clock in the > > device tree, you wouldn't be able to do that, and that was the point > > of this patch. > > Uh, I retract my comment, I was clearly confused here and we're talking > about the same thing. I'm working on a V2 for this series. Are you OK with this if I update the commit message a bit to make it more clear? adam