From patchwork Fri Apr 22 23:45:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuogee Hsieh X-Patchwork-Id: 564955 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 40F95C433EF for ; Fri, 22 Apr 2022 23:45:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229683AbiDVXsc (ORCPT ); Fri, 22 Apr 2022 19:48:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229517AbiDVXsa (ORCPT ); Fri, 22 Apr 2022 19:48:30 -0400 Received: from alexa-out.qualcomm.com (alexa-out.qualcomm.com [129.46.98.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B169F57B38; Fri, 22 Apr 2022 16:45:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1650671135; x=1682207135; h=from:to:cc:subject:date:message-id:mime-version; bh=4lI5QQVTvYeP8wkKNBfN+3WtQcv3wu/e6yW5dEZ3qWQ=; b=e1tgnpCOdd8bDpKJ8wPl5sRRrXOOkgmnrIR70CxQUl0rgJ2CeCiF4RAD vO3YluGEUOACPx+KqaJFSW/wAKJ8W5AUBl+Fs8TdLac8TyOtA++9Gf8RB eCfS+za2tGLXcqCD1x1nVtfMv6DnRPVEdTIKxG0RnITHcOHpjXKxdmGQJ 0=; Received: from ironmsg-lv-alpha.qualcomm.com ([10.47.202.13]) by alexa-out.qualcomm.com with ESMTP; 22 Apr 2022 16:45:34 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg-lv-alpha.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Apr 2022 16:45:33 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Fri, 22 Apr 2022 16:45:33 -0700 Received: from khsieh-linux1.qualcomm.com (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Fri, 22 Apr 2022 16:45:32 -0700 From: Kuogee Hsieh To: , , , , , , , , CC: , , , , , , , Subject: [PATCH] drm/msm/dp: move add fail safe mode to dp_connector_get_mode() Date: Fri, 22 Apr 2022 16:45:23 -0700 Message-ID: <1650671124-14030-1-git-send-email-quic_khsieh@quicinc.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Current DP driver implementation has adding safe mode done at dp_hpd_plug_handle() which is expected to be executed under event thread context. However there is possible circular locking happen (see blow stack trace) after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which is executed under drm_thread context. To break this circular locking, this patch have safe mode added at dp_connector_get_mode() which is executed under drm thread context. Therefore no lock acquired required for &dev->mode_config.mutex while adding fail safe mode since it has been hold by drm thread already. ====================================================== WARNING: possible circular locking dependency detected 5.15.35-lockdep #6 Tainted: G W ------------------------------------------------------ frecon/429 is trying to acquire lock: ffffff808dc3c4e8 (&dev->mode_config.mutex){+.+.}-{3:3}, at: dp_panel_add_fail_safe_mode+0x4c/0xa0 but task is already holding lock: ffffff808dc441e0 (&kms->commit_lock[i]){+.+.}-{3:3}, at: lock_crtcs+0xb4/0x124 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&kms->commit_lock[i]){+.+.}-{3:3}: __mutex_lock_common+0x174/0x1a64 mutex_lock_nested+0x98/0xac lock_crtcs+0xb4/0x124 msm_atomic_commit_tail+0x330/0x748 commit_tail+0x19c/0x278 drm_atomic_helper_commit+0x1dc/0x1f0 drm_atomic_commit+0xc0/0xd8 drm_atomic_helper_set_config+0xb4/0x134 drm_mode_setcrtc+0x688/0x1248 drm_ioctl_kernel+0x1e4/0x338 drm_ioctl+0x3a4/0x684 __arm64_sys_ioctl+0x118/0x154 invoke_syscall+0x78/0x224 el0_svc_common+0x178/0x200 do_el0_svc+0x94/0x13c el0_svc+0x5c/0xec el0t_64_sync_handler+0x78/0x108 el0t_64_sync+0x1a4/0x1a8 -> #2 (crtc_ww_class_mutex){+.+.}-{3:3}: __mutex_lock_common+0x174/0x1a64 ww_mutex_lock+0xb8/0x278 modeset_lock+0x304/0x4ac drm_modeset_lock+0x4c/0x7c drmm_mode_config_init+0x4a8/0xc50 msm_drm_init+0x274/0xac0 msm_drm_bind+0x20/0x2c try_to_bring_up_master+0x3dc/0x470 __component_add+0x18c/0x3c0 component_add+0x1c/0x28 dp_display_probe+0x954/0xa98 platform_probe+0x124/0x15c really_probe+0x1b0/0x5f8 __driver_probe_device+0x174/0x20c driver_probe_device+0x70/0x134 __device_attach_driver+0x130/0x1d0 bus_for_each_drv+0xfc/0x14c __device_attach+0x1bc/0x2bc device_initial_probe+0x1c/0x28 bus_probe_device+0x94/0x178 deferred_probe_work_func+0x1a4/0x1f0 process_one_work+0x5d4/0x9dc worker_thread+0x898/0xccc kthread+0x2d4/0x3d4 ret_from_fork+0x10/0x20 -> #1 (crtc_ww_class_acquire){+.+.}-{0:0}: ww_acquire_init+0x1c4/0x2c8 drm_modeset_acquire_init+0x44/0xc8 drm_helper_probe_single_connector_modes+0xb0/0x12dc drm_mode_getconnector+0x5dc/0xfe8 drm_ioctl_kernel+0x1e4/0x338 drm_ioctl+0x3a4/0x684 __arm64_sys_ioctl+0x118/0x154 invoke_syscall+0x78/0x224 el0_svc_common+0x178/0x200 do_el0_svc+0x94/0x13c el0_svc+0x5c/0xec el0t_64_sync_handler+0x78/0x108 el0t_64_sync+0x1a4/0x1a8 -> #0 (&dev->mode_config.mutex){+.+.}-{3:3}: __lock_acquire+0x2650/0x672c lock_acquire+0x1b4/0x4ac __mutex_lock_common+0x174/0x1a64 mutex_lock_nested+0x98/0xac dp_panel_add_fail_safe_mode+0x4c/0xa0 dp_hpd_plug_handle+0x1f0/0x280 dp_bridge_enable+0x94/0x2b8 drm_atomic_bridge_chain_enable+0x11c/0x168 drm_atomic_helper_commit_modeset_enables+0x500/0x740 msm_atomic_commit_tail+0x3e4/0x748 commit_tail+0x19c/0x278 drm_atomic_helper_commit+0x1dc/0x1f0 drm_atomic_commit+0xc0/0xd8 drm_atomic_helper_set_config+0xb4/0x134 drm_mode_setcrtc+0x688/0x1248 drm_ioctl_kernel+0x1e4/0x338 drm_ioctl+0x3a4/0x684 __arm64_sys_ioctl+0x118/0x154 invoke_syscall+0x78/0x224 el0_svc_common+0x178/0x200 do_el0_svc+0x94/0x13c el0_svc+0x5c/0xec el0t_64_sync_handler+0x78/0x108 el0t_64_sync+0x1a4/0x1a8 Signed-off-by: Kuogee Hsieh Reported-by: Douglas Anderson Reviewed-by: Stephen Boyd --- drivers/gpu/drm/msm/dp/dp_display.c | 6 ------ drivers/gpu/drm/msm/dp/dp_panel.c | 23 +++++++++++++---------- 2 files changed, 13 insertions(+), 16 deletions(-) diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c index 92cd50f..01453db 100644 --- a/drivers/gpu/drm/msm/dp/dp_display.c +++ b/drivers/gpu/drm/msm/dp/dp_display.c @@ -555,12 +555,6 @@ static int dp_hpd_plug_handle(struct dp_display_private *dp, u32 data) mutex_unlock(&dp->event_mutex); - /* - * add fail safe mode outside event_mutex scope - * to avoid potiential circular lock with drm thread - */ - dp_panel_add_fail_safe_mode(dp->dp_display.connector); - /* uevent will complete connection part */ return 0; }; diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c index 1aa9aa8c..23fee42 100644 --- a/drivers/gpu/drm/msm/dp/dp_panel.c +++ b/drivers/gpu/drm/msm/dp/dp_panel.c @@ -151,15 +151,6 @@ static int dp_panel_update_modes(struct drm_connector *connector, return rc; } -void dp_panel_add_fail_safe_mode(struct drm_connector *connector) -{ - /* fail safe edid */ - mutex_lock(&connector->dev->mode_config.mutex); - if (drm_add_modes_noedid(connector, 640, 480)) - drm_set_preferred_mode(connector, 640, 480); - mutex_unlock(&connector->dev->mode_config.mutex); -} - int dp_panel_read_sink_caps(struct dp_panel *dp_panel, struct drm_connector *connector) { @@ -216,7 +207,11 @@ int dp_panel_read_sink_caps(struct dp_panel *dp_panel, goto end; } - dp_panel_add_fail_safe_mode(connector); + /* fail safe edid */ + mutex_lock(&connector->dev->mode_config.mutex); + if (drm_add_modes_noedid(connector, 640, 480)) + drm_set_preferred_mode(connector, 640, 480); + mutex_unlock(&connector->dev->mode_config.mutex); } if (panel->aux_cfg_update_done) { @@ -266,6 +261,14 @@ int dp_panel_get_modes(struct dp_panel *dp_panel, return -EINVAL; } + /* + * add fail safe mode (640x480) here + * since we are executed in drm_thread context, + * no mode_config.mutex acquired required + */ + if (drm_add_modes_noedid(connector, 640, 480)) + drm_set_preferred_mode(connector, 640, 480); + if (dp_panel->edid) return dp_panel_update_modes(connector, dp_panel->edid);