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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09A61C7EE26 for ; Mon, 15 May 2023 01:41:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238099AbjEOBlM (ORCPT ); Sun, 14 May 2023 21:41:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229539AbjEOBlL (ORCPT ); Sun, 14 May 2023 21:41:11 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E38E170B; Sun, 14 May 2023 18:41:05 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 20E5661B5C; Mon, 15 May 2023 01:41:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDD91C433D2; Mon, 15 May 2023 01:41:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684114864; bh=79lWb3D7lA4dEhtUweaJXHJcOyYQuE3lhF99vOoPvus=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KfOxkjKk//cAqrgPGIWIx4zmzZIhWIfhvE70oxhX8EWydVjSWjP3eg6drFuw8cyHp ZyTdyKgKNEtJFsJZG/ez6yVgH9xShT8vAxrQjqOs8UF2l5dmC4otBT2yi6VpZMbZh4 oQGj2qMDasMW4teQ1uoViJGkRIld5ng1KArRJSR00aPNt+beUNFQOQGvydyTEzCNZx 4wY3QptbNtrPVp05iSwm3F+5xofr0ohjyBE8trJ9QHXErQgpa0EhuPe3GGO+vbkUNl szLsneRyHURh100f6C9wr3FAYUt/vq7MAuRYMkcm9SwYgRl6BwXJhxFwKgOCopOoVA S4QS5H6Y4ST1A== Date: Sun, 14 May 2023 18:44:57 -0700 From: Bjorn Andersson To: Dmitry Baryshkov Cc: Andy Gross , Konrad Dybcio , Rob Herring , Krzysztof Kozlowski , linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org Subject: Re: [RFC PATCH] arm64: dts: qcom: add device tree for DB845c working in dual DSI mode Message-ID: <20230515014457.gqbvyyr75bnvi724@ripper> References: <20230118082048.2198715-1-dmitry.baryshkov@linaro.org> <20230118173242.cjh5izohjros6wxd@builder.lan> <20230407164833.2ws22rr4lu6g25dj@ripper> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Fri, Apr 07, 2023 at 08:09:23PM +0300, Dmitry Baryshkov wrote: > On 07/04/2023 19:48, Bjorn Andersson wrote: > > On Wed, Jan 18, 2023 at 08:47:53PM +0200, Dmitry Baryshkov wrote: > > > 18 января 2023 г. 19:32:42 GMT+02:00, Bjorn Andersson пишет: > > > > On Wed, Jan 18, 2023 at 10:20:48AM +0200, Dmitry Baryshkov wrote: > > > > > While we are testing the DB845c working in dual DSI mode (which is > > > > > required for the 4k support), create a separate device tree using this > > > > > configuration. > > > > > > > > > > > > > I don't think it's right to change the DTB on your device depending on > > > > your TV's ability to do 4k or not... > > > > > > > > I ran into this problem when playing around with 4k-support on the RB3 > > > > as well a while back. I was not able to figure out a way to run the > > > > lt9611 off two inputs for the lower resolutions and ended never posted > > > > anything because I couldn't come up with any good solution. > > > > > > > > > This is implemented with the latest lt9611 patchset, referenced in the patch annotation. > > > > > > I posted this as an RFC with the separate dts to let people test dual DSI, DPU wide planes, etc. and to compare that with plain old single link DSI/lt9611. > > > > > > > > > > > > > > > Would it be possible somehow to describe the two ports in DT, but have > > > > the display driver use one or both depending on the number of inputs > > > > needed by the lt9611? > > > > > > This would be very problemsome. Even switching the number of lanes > > > goes against the standard and is not supported by Linux kernel. > > > Supporting switching the host off and on would be a real troublle. > > > > > > > Does this imply that switching resolution in runtime is not possible for > > any of these DSI->HDMI/DP/eDP bridges? > > > > The immediate worry is that we need 4k and non-4k variants of every > > mezzanine (unless we start doing overlays). But beyond that I still > > don't like the fact that you need to change firmware depending on which > > monitor/TV you're going to connect the board to. (And with the current > > boot.img-based design, this is overly cumbersome) > No. With the latest lt9611 driver and with the current msm/msm-next it > should not be necessary to have a separate dtsi. I submitted this patch as > an RFC to let people compare 2xDSI vs single-link cases. Currently I'm happy > with the way it works, so I can probably send this as a patch to main > sdm845-db845c.dtb. > > As a background info: > - lt9611 driver can utilize either one or two DSI links > - drm/msm can output 4k over two DSI links in bonded mode. > - drm/msm will still utilize two DSI links for smaller resolutions > (switching between single and bonded DSI modes doesn't seem practical). > - If just one DSI link is supplied, 1080p is the maximum resolution that can > be supported. > Sorry, I missed your reply earlier. If we can run the lower resolutions off two bonded DSI I think we should make that the default configuration - it's just that when I tried it a few years ago I had problems getting a working output... But much has changed since then. There is a dip switch to allow one of the DSI links to be passed onto one of the HS-connectors, but for anyone to use that they would need a mezzaine dts anyways, so they can unbond the DSIs there. Regards, Bjorn