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[87.123.206.230]) by smtp.gmail.com with ESMTPSA id l8sm832572wme.5.2022.01.17.16.51.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Jan 2022 16:51:41 -0800 (PST) From: Padmanabha Srinivasaiah To: linux-kernel@vger.kernel.org, mripard@kernel.org, airlied@linux.ie, daniel@ffwll.ch, dri-devel@lists.freedesktop.org Cc: emma@anholt.net, treasure4paddy@gmail.com, linux-rpi-kernel@lists.infradead.org Subject: [PATCH] drm/vc4: Fix deadlock on DSI device attach error Date: Tue, 18 Jan 2022 01:51:26 +0100 Message-Id: <20220118005127.29015-1-treasure4paddy@gmail.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" DSI device attach to DSI host will be done with host device's lock held. Un-registering host in "device attach" error path (ex: probe retry) will result in deadlock with below call trace and non operational DSI display. Startup Call trace: [ 35.043036] rt_mutex_slowlock.constprop.21+0x184/0x1b8 [ 35.043048] mutex_lock_nested+0x7c/0xc8 [ 35.043060] device_del+0x4c/0x3e8 [ 35.043075] device_unregister+0x20/0x40 [ 35.043082] mipi_dsi_remove_device_fn+0x18/0x28 [ 35.043093] device_for_each_child+0x68/0xb0 [ 35.043105] mipi_dsi_host_unregister+0x40/0x90 [ 35.043115] vc4_dsi_host_attach+0xf0/0x120 [vc4] [ 35.043199] mipi_dsi_attach+0x30/0x48 [ 35.043209] tc358762_probe+0x128/0x164 [tc358762] [ 35.043225] mipi_dsi_drv_probe+0x28/0x38 [ 35.043234] really_probe+0xc0/0x318 [ 35.043244] __driver_probe_device+0x80/0xe8 [ 35.043254] driver_probe_device+0xb8/0x118 [ 35.043263] __device_attach_driver+0x98/0xe8 [ 35.043273] bus_for_each_drv+0x84/0xd8 [ 35.043281] __device_attach+0xf0/0x150 [ 35.043290] device_initial_probe+0x1c/0x28 [ 35.043300] bus_probe_device+0xa4/0xb0 [ 35.043308] deferred_probe_work_func+0xa0/0xe0 [ 35.043318] process_one_work+0x254/0x700 [ 35.043330] worker_thread+0x4c/0x448 [ 35.043339] kthread+0x19c/0x1a8 [ 35.043348] ret_from_fork+0x10/0x20 Shutdown Call trace: [ 365.565417] Call trace: [ 365.565423] __switch_to+0x148/0x200 [ 365.565452] __schedule+0x340/0x9c8 [ 365.565467] schedule+0x48/0x110 [ 365.565479] schedule_timeout+0x3b0/0x448 [ 365.565496] wait_for_completion+0xac/0x138 [ 365.565509] __flush_work+0x218/0x4e0 [ 365.565523] flush_work+0x1c/0x28 [ 365.565536] wait_for_device_probe+0x68/0x158 [ 365.565550] device_shutdown+0x24/0x348 [ 365.565561] kernel_restart_prepare+0x40/0x50 [ 365.565578] kernel_restart+0x20/0x70 [ 365.565591] __do_sys_reboot+0x10c/0x220 [ 365.565605] __arm64_sys_reboot+0x2c/0x38 [ 365.565619] invoke_syscall+0x4c/0x110 [ 365.565634] el0_svc_common.constprop.3+0xfc/0x120 [ 365.565648] do_el0_svc+0x2c/0x90 [ 365.565661] el0_svc+0x4c/0xf0 [ 365.565671] el0t_64_sync_handler+0x90/0xb8 [ 365.565682] el0t_64_sync+0x180/0x184 Signed-off-by: Padmanabha Srinivasaiah --- drivers/gpu/drm/vc4/vc4_dsi.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c index a229da58962a..9300d3354c51 100644 --- a/drivers/gpu/drm/vc4/vc4_dsi.c +++ b/drivers/gpu/drm/vc4/vc4_dsi.c @@ -1262,7 +1262,6 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host *= host, struct mipi_dsi_device *device) { struct vc4_dsi *dsi =3D host_to_dsi(host); - int ret; =20 dsi->lanes =3D device->lanes; dsi->channel =3D device->channel; @@ -1297,18 +1296,15 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host= *host, return 0; } =20 - ret =3D component_add(&dsi->pdev->dev, &vc4_dsi_ops); - if (ret) { - mipi_dsi_host_unregister(&dsi->dsi_host); - return ret; - } - - return 0; + return component_add(&dsi->pdev->dev, &vc4_dsi_ops); } =20 static int vc4_dsi_host_detach(struct mipi_dsi_host *host, struct mipi_dsi_device *device) { + struct vc4_dsi *dsi =3D host_to_dsi(host); + + component_del(&dsi->pdev->dev, &vc4_dsi_ops); return 0; } =20 @@ -1686,9 +1682,7 @@ static int vc4_dsi_dev_remove(struct platform_device = *pdev) struct device *dev =3D &pdev->dev; struct vc4_dsi *dsi =3D dev_get_drvdata(dev); =20 - component_del(&pdev->dev, &vc4_dsi_ops); mipi_dsi_host_unregister(&dsi->dsi_host); - return 0; } =20 --=20 2.17.1