• Tomi Valkeinen's avatar
    drm/bridge: lt8912b: Fix crash on bridge detach · 44283993
    Tomi Valkeinen authored
    The lt8912b driver, in its bridge detach function, calls
    drm_connector_unregister() and drm_connector_cleanup().
    
    drm_connector_unregister() should be called only for connectors
    explicitly registered with drm_connector_register(), which is not the
    case in lt8912b.
    
    The driver's drm_connector_funcs.destroy hook is set to
    drm_connector_cleanup().
    
    Thus the driver should not call either drm_connector_unregister() nor
    drm_connector_cleanup() in its lt8912_bridge_detach(), as they cause a
    crash on bridge detach:
    
    Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
    Mem abort info:
      ESR = 0x0000000096000006
      EC = 0x25: DABT (current EL), IL = 32 bits
      SET = 0, FnV = 0
      EA = 0, S1PTW = 0
      FSC = 0x06: level 2 translation fault
    Data abort info:
      ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000
      CM = 0, WnR = 0, TnD = 0, TagAccess = 0
      GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
    user pgtable: 4k pages, 48-bit VAs, pgdp=00000000858f3000
    [0000000000000000] pgd=0800000085918003, p4d=0800000085918003, pud=0800000085431003, pmd=0000000000000000
    Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
    Modules linked in: tidss(-) display_connector lontium_lt8912b tc358768 panel_lvds panel_simple drm_dma_helper drm_kms_helper drm drm_panel_orientation_quirks
    CPU: 3 PID: 462 Comm: rmmod Tainted: G        W          6.5.0-rc2+ #2
    Hardware name: Toradex Verdin AM62 on Verdin Development Board (DT)
    pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
    pc : drm_connector_cleanup+0x78/0x2d4 [drm]
    lr : lt8912_bridge_detach+0x54/0x6c [lontium_lt8912b]
    sp : ffff800082ed3a90
    x29: ffff800082ed3a90 x28: ffff0000040c1940 x27: 0000000000000000
    x26: 0000000000000000 x25: dead000000000122 x24: dead000000000122
    x23: dead000000000100 x22: ffff000003fb6388 x21: 0000000000000000
    x20: 0000000000000000 x19: ffff000003fb6260 x18: fffffffffffe56e8
    x17: 0000000000000000 x16: 0010000000000000 x15: 0000000000000038
    x14: 0000000000000000 x13: ffff800081914b48 x12: 000000000000040e
    x11: 000000000000015a x10: ffff80008196ebb8 x9 : ffff800081914b48
    x8 : 00000000ffffefff x7 : ffff0000040c1940 x6 : ffff80007aa649d0
    x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff80008159e008
    x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
    Call trace:
     drm_connector_cleanup+0x78/0x2d4 [drm]
     lt8912_bridge_detach+0x54/0x6c [lontium_lt8912b]
     drm_bridge_detach+0x44/0x84 [drm]
     drm_encoder_cleanup+0x40/0xb8 [drm]
     drmm_encoder_alloc_release+0x1c/0x30 [drm]
     drm_managed_release+0xac/0x148 [drm]
     drm_dev_put.part.0+0x88/0xb8 [drm]
     devm_drm_dev_init_release+0x14/0x24 [drm]
     devm_action_release+0x14/0x20
     release_nodes+0x5c/0x90
     devres_release_all+0x8c/0xe0
     device_unbind_cleanup+0x18/0x68
     device_release_driver_internal+0x208/0x23c
     driver_detach+0x4c/0x94
     bus_remove_driver+0x70/0xf4
     driver_unregister+0x30/0x60
     platform_driver_unregister+0x14/0x20
     tidss_platform_driver_exit+0x18/0xb2c [tidss]
     __arm64_sys_delete_module+0x1a0/0x2b4
     invoke_syscall+0x48/0x110
     el0_svc_common.constprop.0+0x60/0x10c
     do_el0_svc_compat+0x1c/0x40
     el0_svc_compat+0x40/0xac
     el0t_32_sync_handler+0xb0/0x138
     el0t_32_sync+0x194/0x198
    Code: 9104a276 f2fbd5b7 aa0203e1 91008af8 (f85c0420)
    
    Fixes: 30e2ae94 ("drm/bridge: Introduce LT8912B DSI to HDMI bridge")
    Signed-off-by: default avatarTomi Valkeinen <tomi.valkeinen@ideasonboard.com>
    Reviewed-by: default avatarRobert Foss <rfoss@kernel.org>
    Signed-off-by: default avatarRobert Foss <rfoss@kernel.org>
    Link: https://patchwork.freedesktop.org/patch/msgid/20230804-lt8912b-v1-2-c542692c6a2f@ideasonboard.com
    44283993
lontium-lt8912b.c 17.2 KB