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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 3B6C4C2D0E4 for ; Tue, 17 Nov 2020 09:20:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D9D4F2417E for ; Tue, 17 Nov 2020 09:20:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="qmSlsSfT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727240AbgKQJTx (ORCPT ); Tue, 17 Nov 2020 04:19:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:41168 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726200AbgKQJTw (ORCPT ); Tue, 17 Nov 2020 04:19:52 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2B4E02417E; Tue, 17 Nov 2020 09:19:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605604791; bh=W2obSm8Q5WV3J0n3YYVGmzEgDz3xGzgFoH4NhA880LY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=qmSlsSfThTdhsSFxqYJ8Ssxf74VZV4gCGKJP6Xzh0J0UaDYFvOAcer//u1GVrLJcR yUOwRen2klvD5MHwIVJBsDzZic9MqzCy4Xjw7vOaDH8wg53nUmusjicPu4fcpJqpyd Bv8+6izebH3AYsBoF21oTj670rpQE/fJI9fgsGsI= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1kex9Q-00BHax-U0; Tue, 17 Nov 2020 09:19:49 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 17 Nov 2020 09:19:48 +0000 From: Marc Zyngier To: Neil Armstrong Cc: Kevin Hilman , Jerome Brunet , Martin Blumenstingl , kernel-team@android.com, dri-devel@lists.freedesktop.org, linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/4] drm/meson: Module removal fixes In-Reply-To: <0b429c41-421a-2ae0-66a0-a142c56acadd@baylibre.com> References: <20201116200744.495826-1-maz@kernel.org> <0b429c41-421a-2ae0-66a0-a142c56acadd@baylibre.com> User-Agent: Roundcube Webmail/1.4.9 Message-ID: <09de6683eea499cfd83ab0c67e0cdca2@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: narmstrong@baylibre.com, khilman@baylibre.com, jbrunet@baylibre.com, martin.blumenstingl@googlemail.com, kernel-team@android.com, dri-devel@lists.freedesktop.org, linux-amlogic@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Neil, On 2020-11-17 08:49, Neil Armstrong wrote: > Hi Marc, > > On 16/11/2020 21:07, Marc Zyngier wrote: >> Hi all, >> >> Having recently moved over to a top-of-the-tree u-boot on one of my >> VIM3L systems in order to benefit from unrelated improvements >> (automatic PCIe detection, EFI...), I faced the issue that my kernel >> would hang like this: >> >> [ OK ] Finished Helper to synchronize boot up for ifupdown. >> [ OK ] Started Rule-based Manager for Device Events and Files. >> [ 7.114516] VDDCPU: supplied by regulator-dummy >> [ OK ] Found device /dev/ttyAML0. >> [ 7.146862] meson-drm ff900000.vpu: Queued 2 outputs on vpu >> [ 7.169630] fb0: switching to meson-drm-fb from simple >> [ 7.169944] Console: switching to colour dummy device 80x25 >> [ 7.179250] meson-drm ff900000.vpu: CVBS Output connector not >> available >> >> and that's it. >> >> After some poking around, I figured out that it is in the >> meson-dw-hdmi module that the CPU was hanging... > > I'll be interested in having your kernel config, I never had such > report > since I enabled HDMI support in U-Boot a few years ago. Yeah, I was pretty surprised too. I have a hunch that this is caused by u-boot DT exposing an extra MMIO region (dubbed "hhi") that gets picked up by the kernel driver. *Not* having the region in the DT (as in the kernel's version of the same DT) makes the driver work exactly once: Decompiled u-boot DT: hdmi-tx@0 { compatible = "amlogic,meson-g12a-dw-hdmi"; reg = <0x00 0x00 0x00 0x10000 0x00 0x3c000 0x00 0x1000>; [...] reg-names = "hdmitx\0hhi"; Decompiled kernel DT: hdmi-tx@0 { compatible = "amlogic,meson-g12a-dw-hdmi"; reg = <0x00 0x00 0x00 0x10000>; There seem to be some complex interactions between the HDMI driver and the DRM driver, both using this MMIO region at any given time. But I admit not having tried very hard to follow the DRM maze of intricate callbacks. All I needed was this box to reliably boot with the firmware-provided DT. You can find a reasonably recent version of my config at [1]. M. [1] http://www.loen.fr/tmp/Config.full-arm64 -- Jazz is not dead. It just smells funny...