[Intel-gfx] [PATCH 1/3] drm/dp_mst: Fix the DDC I2C device unregistration of an MST port

[Lisovskiy, Stanislav]

On Mon, Jun 08, 2020 at 12:25:20AM +0300, Imre Deak wrote:
> The WARN below triggers during the removal of an MST port. The problem
> is that the parent device's (the connector's kdev) sysfs directory is
> removed recursively when the connector is unregistered (even though the
> I2C device holds a reference on the parent device). To fix this set
> first the Peer Device Type to none which will remove the I2C device.
> 
> Note that atm, inconsistently, the parent of the I2C device is initially set to
> the DRM kdev and after a Connection Status Notification the parent may be reset
> to be the connector's kdev. This problem is addressed by the next patch.

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>

> 
> [ 4462.989299] ------------[ cut here ]------------
> [ 4463.014940] sysfs group 'power' not found for kobject 'i2c-24'
> [ 4463.034664] WARNING: CPU: 0 PID: 970 at fs/sysfs/group.c:281 sysfs_remove_group+0x71/0x80
> [ 4463.044357] Modules linked in: snd_hda_intel i915 drm_kms_helper(O) drm netconsole snd_hda_codec_hdmi mei_hdcp x86_pkg_temp_thermal coretemp crct10dif_pclmul snd_intel_dspcf
> g crc32_pclmul snd_hda_codec snd_hwdep ghash_clmulni_intel snd_hda_core asix usbnet kvm_intel mii i2c_algo_bit snd_pcm syscopyarea sysfillrect e1000e sysimgblt fb_sys_fops prim
> e_numbers ptp pps_core i2c_i801 r8169 mei_me realtek mei [last unloaded: drm]
> [ 4463.044399] CPU: 0 PID: 970 Comm: kworker/0:2 Tainted: G           O      5.7.0+ #172
> [ 4463.044402] Hardware name: Intel Corporation Tiger Lake Client Platform/TigerLake U DDR4 SODIMM RVP
> [ 4463.044423] Workqueue: events drm_dp_delayed_destroy_work [drm_kms_helper]
> [ 4463.044428] RIP: 0010:sysfs_remove_group+0x71/0x80
> [ 4463.044431] Code: 48 89 df 5b 5d 41 5c e9 cd b6 ff ff 48 89 df e8 95 b4 ff ff eb cb 49 8b 14 24 48 8b 75 00 48 c7 c7 20 0f 3f 82 e8 9f c5 d7 ff <0f> 0b 5b 5d 41 5c c3 0f 1f
> 84 00 00 00 00 00 48 85 f6 74 31 41 54
> [ 4463.044433] RSP: 0018:ffffc900018bfbf0 EFLAGS: 00010282
> [ 4463.044436] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001
> [ 4463.044439] RDX: 0000000080000001 RSI: ffff88849e828f38 RDI: 00000000ffffffff
> [ 4463.052970] [drm:drm_atomic_get_plane_state [drm]] Added [PLANE:100:plane 2B] 00000000c2160caa state to 00000000d172564a
> [ 4463.070533] RBP: ffffffff820cea20 R08: ffff88847f4b8958 R09: 0000000000000000
> [ 4463.070535] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88848a725018
> [ 4463.070537] R13: 0000000000000000 R14: ffffffff827090e0 R15: 0000000000000002
> [ 4463.070539] FS:  0000000000000000(0000) GS:ffff88849e800000(0000) knlGS:0000000000000000
> [ 4463.070541] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 4463.070543] CR2: 00007fdf8a756538 CR3: 0000000489684001 CR4: 0000000000760ef0
> [ 4463.070545] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 4463.070547] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [ 4463.070549] PKRU: 55555554
> [ 4463.070551] Call Trace:
> [ 4463.070560]  device_del+0x84/0x400
> [ 4463.070571]  cdev_device_del+0x10/0x30
> [ 4463.070578]  put_i2c_dev+0x69/0x80
> [ 4463.070584]  i2cdev_detach_adapter+0x2e/0x60
> [ 4463.070591]  notifier_call_chain+0x34/0x90
> [ 4463.070599]  blocking_notifier_call_chain+0x3f/0x60
> [ 4463.070606]  device_del+0x7c/0x400
> [ 4463.087817]  ? lockdep_init_map_waits+0x57/0x210
> [ 4463.087825]  device_unregister+0x11/0x60
> [ 4463.087829]  i2c_del_adapter+0x249/0x310
> [ 4463.087846]  drm_dp_port_set_pdt+0x6b/0x2c0 [drm_kms_helper]
> [ 4463.087862]  drm_dp_delayed_destroy_work+0x2af/0x350 [drm_kms_helper]
> [ 4463.087876]  process_one_work+0x268/0x600
> [ 4463.105438]  ? __schedule+0x30c/0x920
> [ 4463.105451]  worker_thread+0x37/0x380
> [ 4463.105457]  ? process_one_work+0x600/0x600
> [ 4463.105462]  kthread+0x140/0x160
> [ 4463.105466]  ? kthread_park+0x80/0x80
> [ 4463.105474]  ret_from_fork+0x24/0x50
> 
> Cc: <stable at vger.kernel.org>
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 2a309fb2c4cc..02c800b8199f 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -4669,12 +4669,13 @@ static void drm_dp_tx_work(struct work_struct *work)
>  static inline void
>  drm_dp_delayed_destroy_port(struct drm_dp_mst_port *port)
>  {
> +	drm_dp_port_set_pdt(port, DP_PEER_DEVICE_NONE, port->mcs);
> +
>  	if (port->connector) {
>  		drm_connector_unregister(port->connector);
>  		drm_connector_put(port->connector);
>  	}
>  
> -	drm_dp_port_set_pdt(port, DP_PEER_DEVICE_NONE, port->mcs);
>  	drm_dp_mst_put_port_malloc(port);
>  }
>  
> -- 
> 2.23.1
> 
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