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 45173C7EE2F for ; Mon, 29 May 2023 08:02:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231591AbjE2ICj (ORCPT ); Mon, 29 May 2023 04:02:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229556AbjE2ICf (ORCPT ); Mon, 29 May 2023 04:02:35 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6AFFEA7; Mon, 29 May 2023 01:02:33 -0700 (PDT) Received: from [IPV6:2001:b07:2ed:14ed:a962:cd4d:a84:1eab] (unknown [IPv6:2001:b07:2ed:14ed:a962:cd4d:a84:1eab]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) (Authenticated sender: kholk11) by madras.collabora.co.uk (Postfix) with ESMTPSA id 79C1C6605961; Mon, 29 May 2023 09:02:31 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1685347352; bh=A4ZNREQoh5/KC7x7Aai+h2epscmtPk1u6BBSzcPw1yE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=dX6SHWyOxgUzPCOpqEMFwfU+oDrE2Q9SSL6ricQ3zd7lGcaD3r9IwZdbfbjLB40Ik Sp4UqpDoKXrblE28lnsvwltd+8w2d1o57AMCrzERi6Zr3wrjVGUhC+zN5y5Tpk1kD6 eOpc8OW1TZ+ytBLa4U0aLa/o2vJCU+gXldjU5EoOJB8mUwz08lgUMnRqyw811AxiRX k4EIiiMVX3rQP1iElyi+w4xNvoFcIfxZAzWHGN+5I1x9LAg0ZCUnAp+6f3dN5rJ7BN X6qv/9KC+Oc3PFU/EKQzH+OcXUw0LAmu+4wh/6fRoIt/mkdD5khf6bc9v01SLa+C3B fLDu65wLzWeSg== Message-ID: Date: Mon, 29 May 2023 10:02:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH] arm64: dts: mediatek: mt8173-elm: remove panel model number in DT Content-Language: en-US To: Doug Anderson , Icenowy Zheng , Pin-yen Lin Cc: Rob Herring , Krzysztof Kozlowski , Matthias Brugger , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, dri-devel@lists.freedesktop.org References: <20230526100801.16310-1-uwu@icenowy.me> From: AngeloGioacchino Del Regno In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 26/05/23 16:24, Doug Anderson ha scritto: > Hi, > > On Fri, May 26, 2023 at 3:09 AM Icenowy Zheng wrote: >> >> Currently a specific panel number is used in the Elm DTSI, which is >> corresponded to a 12" panel. However, according to the official Chrome >> OS devices document, Elm refers to Acer Chromebook R13, which, as the >> name specifies, uses a 13.3" panel, which comes with EDID information. >> >> As the kernel currently prioritizes the hardcoded timing parameters >> matched with the panel number compatible, a wrong timing will be applied >> to the 13.3" panel on Acer Chromebook R13, which leads to blank display. >> >> Because the Elm DTSI is shared with Hana board, and Hana corresponds to >> multiple devices from 11" to 14", a certain panel model number shouldn't >> be present, and driving the panel according to its EDID information is >> necessary. >> >> Signed-off-by: Icenowy Zheng >> --- >> arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) > > We went through a bunch of back-and-forth here but in the end in the > ChromeOS tree we have "edp-panel" as the "compatible" here in the > ChromeOS 5.15 tree and this makes sense. > > Reviewed-by: Douglas Anderson > > ...in theory one would wish for a "Fixes" tag, but I think in previous > discussions it was decided that it was too complicated. Hardcoding the > other compatible string has always been technically wrong, but I guess > it worked at some point in time. The more correct way (as you're doing > here) needs the DP AUX bus support and the generic eDP panels, both of > which are significantly newer than the elm dts. So I guess leaving no > "Fixes" tag is OK, or perhaps you could do the somewhat weak: > > Fixes: c2d94f72140a ("arm64: dts: mediatek: mt8173-elm: Move display > to ps8640 auxiliary bus") I remember I didn't change the compatible to panel-edp because it didn't work at that time, but it does now... I'm not sure what actually fixed that and if the commit(s) was/were backported to that suggested point, so I would leave the Fixes tag out, as that may break older kernels. Anyway, for this commit: Reviewed-by: AngeloGioacchino Del Regno