From patchwork Fri Jul 21 16:05:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 705013 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 62E45C001DE for ; Fri, 21 Jul 2023 19:19:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231922AbjGUTTn (ORCPT ); Fri, 21 Jul 2023 15:19:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232052AbjGUTTi (ORCPT ); Fri, 21 Jul 2023 15:19:38 -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 3C4E13A90; Fri, 21 Jul 2023 12:19:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A843861D6D; Fri, 21 Jul 2023 19:19:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8F65FC433C7; Fri, 21 Jul 2023 19:19:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689967173; bh=VknH39d+fypFBtbpKy9Ks9499orhFKGibNkjywSPOo8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TwfHAh4dqdvIDSnWyOrbWr4scVHbxbgthT5ieOlaqy9DMKSJDh/azXW9+8q7icfQb wvRcfGgYIhspri592yY+F/y5s6+jXjcl2RfEEwIIjIoC9fx8IpiP6x9A/DEmqpzAWA aLcNZXU3sch42MqttSnd6swrBUacSkcUR6j6I6js= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Moritz Duge , Thomas Zimmermann , Torsten Krah , Paul Schyska , Daniel Vetter , David Airlie , =?utf-8?q?Noralf_Tr=C3=B8nnes?= , Maarten Lankhorst , Maxime Ripard , Javier Martinez Canillas , Russell King , Inki Dae , Seung-Woo Kim , Kyungmin Park , Krzysztof Kozlowski , Patrik Jakobsson , Rob Clark , Abhinav Kumar , Dmitry Baryshkov , Tomi Valkeinen , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , "Pan, Xinhui" , Thierry Reding , Mikko Perttunen , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, linux-tegra@vger.kernel.org, alexandru.gagniuc@hp.com, Mario Limonciello Subject: [PATCH 6.1 069/223] drm/client: Send hotplug event after registering a client Date: Fri, 21 Jul 2023 18:05:22 +0200 Message-ID: <20230721160523.804204932@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230721160520.865493356@linuxfoundation.org> References: <20230721160520.865493356@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org From: Thomas Zimmermann commit 27655b9bb9f0d9c32b8de8bec649b676898c52d5 upstream. Generate a hotplug event after registering a client to allow the client to configure its display. Remove the hotplug calls from the existing clients for fbdev emulation. This change fixes a concurrency bug between registering a client and receiving events from the DRM core. The bug is present in the fbdev emulation of all drivers. The fbdev emulation currently generates a hotplug event before registering the client to the device. For each new output, the DRM core sends an additional hotplug event to each registered client. If the DRM core detects first output between sending the artificial hotplug and registering the device, the output's hotplug event gets lost. If this is the first output, the fbdev console display remains dark. This has been observed with amdgpu and fbdev-generic. Fix this by adding hotplug generation directly to the client's register helper drm_client_register(). Registering the client and receiving events are serialized by struct drm_device.clientlist_mutex. So an output is either configured by the initial hotplug event, or the client has already been registered. The bug was originally added in commit 6e3f17ee73f7 ("drm/fb-helper: generic: Call drm_client_add() after setup is done"), in which adding a client and receiving a hotplug event switched order. It was hidden, as most hardware and drivers have at least on static output configured. Other drivers didn't use the internal DRM client or still had struct drm_mode_config_funcs.output_poll_changed set. That callback handled hotplug events as well. After not setting the callback in amdgpu in commit 0e3172bac3f4 ("drm/amdgpu: Don't set struct drm_driver.output_poll_changed"), amdgpu did not show a framebuffer console if output events got lost. The bug got copy-pasted from fbdev-generic into the other fbdev emulation. Reported-by: Moritz Duge Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/2649 Fixes: 6e3f17ee73f7 ("drm/fb-helper: generic: Call drm_client_add() after setup is done") Fixes: 8ab59da26bc0 ("drm/fb-helper: Move generic fbdev emulation into separate source file") Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for GEM DMA helpers") Fixes: 63c381552f69 ("drm/armada: Implement fbdev emulation as in-kernel client") Fixes: 49953b70e7d3 ("drm/exynos: Implement fbdev emulation as in-kernel client") Fixes: 8f1aaccb04b7 ("drm/gma500: Implement client-based fbdev emulation") Fixes: 940b869c2f2f ("drm/msm: Implement fbdev emulation as in-kernel client") Fixes: 9e69bcd88e45 ("drm/omapdrm: Implement fbdev emulation as in-kernel client") Fixes: e317a69fe891 ("drm/radeon: Implement client-based fbdev emulation") Fixes: 71ec16f45ef8 ("drm/tegra: Implement fbdev emulation as in-kernel client") Fixes: 0e3172bac3f4 ("drm/amdgpu: Don't set struct drm_driver.output_poll_changed") Signed-off-by: Thomas Zimmermann Tested-by: Moritz Duge Tested-by: Torsten Krah Tested-by: Paul Schyska Cc: Daniel Vetter Cc: David Airlie Cc: Noralf Trønnes Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Javier Martinez Canillas Cc: Russell King Cc: Inki Dae Cc: Seung-Woo Kim Cc: Kyungmin Park Cc: Krzysztof Kozlowski Cc: Patrik Jakobsson Cc: Rob Clark Cc: Abhinav Kumar Cc: Dmitry Baryshkov Cc: Tomi Valkeinen Cc: Alex Deucher Cc: "Christian König" Cc: "Pan, Xinhui" Cc: Thierry Reding Cc: Mikko Perttunen Cc: dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-arm-msm@vger.kernel.org Cc: freedreno@lists.freedesktop.org Cc: amd-gfx@lists.freedesktop.org Cc: linux-tegra@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: # v5.2+ Reviewed-by: Javier Martinez Canillas Reviewed-by: Dmitry Baryshkov # msm Link: https://patchwork.freedesktop.org/patch/msgid/20230710091029.27503-1-tzimmermann@suse.de (cherry picked from commit 27655b9bb9f0d9c32b8de8bec649b676898c52d5) [ Dropped changes to drivers/gpu/drm/armada/armada_fbdev.c as 174c3c38e3a2 drm/armada: Initialize fbdev DRM client was introduced in 6.5-rc1. Dropped changes to exynos, msm, omapdrm, radeon, tegra drivers as missing code these commits introduced: 99286486d674 drm/exynos: Initialize fbdev DRM client 841ef552b141 drm/msm: Initialize fbdev DRM client 9e69bcd88e45 drm/omapdrm: Implement fbdev emulation as in-kernel client e317a69fe891 drm/radeon: Implement client-based fbdev emulation 9b926bcf2636 drm/radeon: Only build fbdev if DRM_FBDEV_EMULATION is set 25dda38e0b07 drm/tegra: Initialize fbdev DRM client 8f1aaccb04b7 drm/gma500: Implement client-based fbdev emulation b79fe9abd58b drm/fbdev-dma: Implement fbdev emulation for GEM DMA helpers Move code for drm-fbdev-generic.c to matching file in 6.1.y because these commits haven't happened in 6.1.y. 8ab59da26bc0 drm/fb-helper: Move generic fbdev emulation into separate source file b9c93f4ec737 drm/fbdev-generic: Rename symbols ] Cc: alexandru.gagniuc@hp.com Link: https://lore.kernel.org/stable/SJ0PR84MB20882EEA1ABB36F60E845E378F5AA@SJ0PR84MB2088.NAMPRD84.PROD.OUTLOOK.COM/ Signed-off-by: Mario Limonciello Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_client.c | 21 +++++++++++++++++++++ drivers/gpu/drm/drm_fb_helper.c | 4 ---- 2 files changed, 21 insertions(+), 4 deletions(-) --- a/drivers/gpu/drm/drm_client.c +++ b/drivers/gpu/drm/drm_client.c @@ -122,13 +122,34 @@ EXPORT_SYMBOL(drm_client_init); * drm_client_register() it is no longer permissible to call drm_client_release() * directly (outside the unregister callback), instead cleanup will happen * automatically on driver unload. + * + * Registering a client generates a hotplug event that allows the client + * to set up its display from pre-existing outputs. The client must have + * initialized its state to able to handle the hotplug event successfully. */ void drm_client_register(struct drm_client_dev *client) { struct drm_device *dev = client->dev; + int ret; mutex_lock(&dev->clientlist_mutex); list_add(&client->list, &dev->clientlist); + + if (client->funcs && client->funcs->hotplug) { + /* + * Perform an initial hotplug event to pick up the + * display configuration for the client. This step + * has to be performed *after* registering the client + * in the list of clients, or a concurrent hotplug + * event might be lost; leaving the display off. + * + * Hold the clientlist_mutex as for a regular hotplug + * event. + */ + ret = client->funcs->hotplug(client); + if (ret) + drm_dbg_kms(dev, "client hotplug ret=%d\n", ret); + } mutex_unlock(&dev->clientlist_mutex); } EXPORT_SYMBOL(drm_client_register); --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -2634,10 +2634,6 @@ void drm_fbdev_generic_setup(struct drm_ preferred_bpp = 32; fb_helper->preferred_bpp = preferred_bpp; - ret = drm_fbdev_client_hotplug(&fb_helper->client); - if (ret) - drm_dbg_kms(dev, "client hotplug ret=%d\n", ret); - drm_client_register(&fb_helper->client); } EXPORT_SYMBOL(drm_fbdev_generic_setup);