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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EF25DE81BA4 for ; Mon, 9 Feb 2026 11:40:16 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0F98110E3C1; Mon, 9 Feb 2026 11:40:16 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="LsCNZmAy"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5A88510E3C1 for ; Mon, 9 Feb 2026 11:40:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1770637213; bh=YaTGcZwimloW1kgdEu8K+8Kr1kYVJjhPDsKxgwaC/PM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=LsCNZmAyezhl3cvyfXrtT3fLv3wCWzZ9+ABlrTSDaHixCeCjjxhzsU2Ofp6WSAXOx lTbIG1xnRmaHn9+L82ux7AgGEQB7215cUmY8YwwMGZ6+QpWdjNngskX1QdUsnHtfvZ MOS8CdmxtKmMn6AaDExoUwNnLOiOOJEgpmIjvUProq0KvQrqCUZgmhdcPvBUM3434a 8MsC44jgeZAi5LeDa2lrMuE64kprokKgDPFCcn+OZRCrprZefZgwOMDXyZQLT2rKT3 gn5YhQcM1rv8yVHlBQC6JDzp5x6Xv5Rc37TFp/fKZKnuh8TxkaX8tsdXGuuFTxXm8d IvXe1leqXwmZQ== Received: from [192.168.1.100] (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by bali.collaboradmins.com (Postfix) with ESMTPSA id 7C1E117E13D5; Mon, 9 Feb 2026 12:40:13 +0100 (CET) Message-ID: <5535ac41-efb8-4bf5-91bb-9b6f63517e8f@collabora.com> Date: Mon, 9 Feb 2026 12:40:13 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/mediatek: dsi: Store driver data before invoking mipi_dsi_host_register To: Luca Leonardo Scorcia , linux-mediatek@lists.infradead.org Cc: Chun-Kuang Hu , Philipp Zabel , David Airlie , Simona Vetter , Matthias Brugger , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20260209090516.14369-1-l.scorcia@gmail.com> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: <20260209090516.14369-1-l.scorcia@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Il 09/02/26 10:05, Luca Leonardo Scorcia ha scritto: > The call to mipi_dsi_host_register triggers a callback to mtk_dsi_bind, > which uses dev_get_drvdata to retrieve the mtk_dsi struct, so this > structure needs to be stored inside the driver data before invoking it. > > As drvdata is currently uninitialized it leads to a crash when > registering the DSI DRM encoder right after acquiring > the mode_config.idr_mutex, blocking all subsequent DRM operations. > > Fixes the following crash during mediatek-drm probe (tested on Xiaomi > Smart Clock x04g): > > Unable to handle kernel NULL pointer dereference at virtual address > 0000000000000040 > [...] > Modules linked in: mediatek_drm(+) drm_display_helper cec drm_client_lib > drm_dma_helper drm_kms_helper panel_simple > [...] > Call trace: > drm_mode_object_add+0x58/0x98 (P) > __drm_encoder_init+0x48/0x140 > drm_encoder_init+0x6c/0xa0 > drm_simple_encoder_init+0x20/0x34 [drm_kms_helper] > mtk_dsi_bind+0x34/0x13c [mediatek_drm] > component_bind_all+0x120/0x280 > mtk_drm_bind+0x284/0x67c [mediatek_drm] > try_to_bring_up_aggregate_device+0x23c/0x320 > __component_add+0xa4/0x198 > component_add+0x14/0x20 > mtk_dsi_host_attach+0x78/0x100 [mediatek_drm] > mipi_dsi_attach+0x2c/0x50 > panel_simple_dsi_probe+0x4c/0x9c [panel_simple] > mipi_dsi_drv_probe+0x1c/0x28 > really_probe+0xc0/0x3dc > __driver_probe_device+0x80/0x160 > driver_probe_device+0x40/0x120 > __device_attach_driver+0xbc/0x17c > bus_for_each_drv+0x88/0xf0 > __device_attach+0x9c/0x1cc > device_initial_probe+0x54/0x60 > bus_probe_device+0x34/0xa0 > device_add+0x5b0/0x800 > mipi_dsi_device_register_full+0xdc/0x16c > mipi_dsi_host_register+0xc4/0x17c > mtk_dsi_probe+0x10c/0x260 [mediatek_drm] > platform_probe+0x5c/0xa4 > really_probe+0xc0/0x3dc > __driver_probe_device+0x80/0x160 > driver_probe_device+0x40/0x120 > __driver_attach+0xc8/0x1f8 > bus_for_each_dev+0x7c/0xe0 > driver_attach+0x24/0x30 > bus_add_driver+0x11c/0x240 > driver_register+0x68/0x130 > __platform_register_drivers+0x64/0x160 > mtk_drm_init+0x24/0x1000 [mediatek_drm] > do_one_initcall+0x60/0x1d0 > do_init_module+0x54/0x240 > load_module+0x1838/0x1dc0 > init_module_from_file+0xd8/0xf0 > __arm64_sys_finit_module+0x1b4/0x428 > invoke_syscall.constprop.0+0x48/0xc8 > do_el0_svc+0x3c/0xb8 > el0_svc+0x34/0xe8 > el0t_64_sync_handler+0xa0/0xe4 > el0t_64_sync+0x198/0x19c > Code: 52800022 941004ab 2a0003f3 37f80040 (29005a80) > ---[ end trace 0000000000000000 ]--- > > Signed-off-by: Luca Leonardo Scorcia Reviewed-by: AngeloGioacchino Del Regno ... but wait, what have I just read? Xiaomi Smart Clock?! MT8167? Are you running upstream on this device? If so, why don't you also contribute a nice devicetree to get this device finally upstream?!?! :-) Cheers, Angelo > --- > drivers/gpu/drm/mediatek/mtk_dsi.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c > index 4c2983852596..2358407b8a6b 100644 > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c > @@ -1232,6 +1232,8 @@ static int mtk_dsi_probe(struct platform_device *pdev) > > dsi->host.ops = &mtk_dsi_ops; > dsi->host.dev = dev; > + platform_set_drvdata(pdev, dsi); > + > ret = mipi_dsi_host_register(&dsi->host); > if (ret < 0) > return dev_err_probe(dev, ret, "Failed to register DSI host\n"); > @@ -1254,8 +1256,6 @@ static int mtk_dsi_probe(struct platform_device *pdev) > > init_waitqueue_head(&dsi->irq_wait_queue); > > - platform_set_drvdata(pdev, dsi); > - > dsi->bridge.of_node = dev->of_node; > dsi->bridge.type = DRM_MODE_CONNECTOR_DSI; >