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Subject: Re: [RFC PATCH v5 0/9] Add Tegra driver for video capture
From:   Sowjanya Komatineni <skomatineni@nvidia.com>
To:     Hans Verkuil <hverkuil@xs4all.nl>, <thierry.reding@gmail.com>,
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On 3/30/20 9:16 AM, Sowjanya Komatineni wrote:
>
> On 3/30/20 4:02 AM, Hans Verkuil wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> On 3/30/20 12:04 PM, Hans Verkuil wrote:
>>> Hi Sowjanya,
>>>
>>> On 3/23/20 6:52 PM, Sowjanya Komatineni wrote:
>>>> This series adds Tegra210 VI and CSI driver for built-in test pattern
>>>> generator (TPG) capture.
>>>>
>>>> Tegra210 supports max 6 channels on VI and 6 ports on CSI where each
>>>> CSI port is one-to-one mapped to VI channel for video capture.
>>>>
>>>> This series has TPG support only where it creates hard media links
>>>> between CSI subdevice and VI video device without device graphs.
>>>>
>>>> v4l2-compliance results are available below the patch diff.
>>>>
>>>> [v5]:=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Includes,
>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 - v4 feedback
>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 - fix for venc powergate mc reset order=
.
>>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 - fix to have unbind and bind work duri=
ng v4l2-ctl sleep and=20
>>>> streaming.
>>> Unfortunately, I still crash on this.
>>>
>>> I do the following:
>>>
>>> Run: v4l2-ctl --stream-mmap
>>>
>>> Then, from another shell as root:
>>>
>>> cd /sys/devices/platform/50000000.host1x/tegra-video/driver
>>> echo -n tegra-video > unbind
>>>
>>> I get this crash:
>>>
>>> [=C2=A0 315.691971] Unable to handle kernel NULL pointer dereference at=
=20
>>> virtual address 00000000000000b0
>>> [=C2=A0 315.700749] Mem abort info:
>>> [=C2=A0 315.703536]=C2=A0=C2=A0 ESR =3D 0x96000004
>>> [=C2=A0 315.706587]=C2=A0=C2=A0 EC =3D 0x25: DABT (current EL), IL =3D =
32 bits
>>> [=C2=A0 315.711886]=C2=A0=C2=A0 SET =3D 0, FnV =3D 0
>>> [=C2=A0 315.714933]=C2=A0=C2=A0 EA =3D 0, S1PTW =3D 0
>>> [=C2=A0 315.718064] Data abort info:
>>> [=C2=A0 315.720936]=C2=A0=C2=A0 ISV =3D 0, ISS =3D 0x00000004
>>> [=C2=A0 315.724763]=C2=A0=C2=A0 CM =3D 0, WnR =3D 0
>>> [=C2=A0 315.727726] user pgtable: 4k pages, 48-bit VAs,=20
>>> pgdp=3D0000000178ee8000
>>> [=C2=A0 315.734152] [00000000000000b0] pgd=3D0000000000000000
>>> [=C2=A0 315.739024] Internal error: Oops: 96000004 [#1] PREEMPT SMP
>>> [=C2=A0 315.744584] Modules linked in: r8152 nouveau lp855x_bl tegra_dr=
m ttm
>>> [=C2=A0 315.750942] CPU: 3 PID: 2206 Comm: bash Tainted: G W=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=20
>>> 5.6.0-rc1-arm64 #118
>>> [=C2=A0 315.759017] Hardware name: NVIDIA Jetson TX1 Developer Kit (DT)
>>> [=C2=A0 315.764927] pstate: 20000085 (nzCv daIf -PAN -UAO)
>>> [=C2=A0 315.769718] pc : _raw_write_lock_irqsave+0xb0/0x2b8
>>> [=C2=A0 315.774590] lr : ida_free+0x48/0x158
>>> [=C2=A0 315.778155] sp : ffff800011d8bba0
>>> [=C2=A0 315.781462] x29: ffff800011d8bba0 x28: ffff0000f4095400
>>> [=C2=A0 315.786766] x27: 0000000000000000 x26: 0000000000000000
>>> [=C2=A0 315.792070] x25: 0000000000000000 x24: 0000000000000000
>>> [=C2=A0 315.797372] x23: ffff0000f21ad400 x22: ffff0000f5c93000
>>> [=C2=A0 315.802674] x21: ffff0000f4095400 x20: ffff0000f86b5540
>>> [=C2=A0 315.807975] x19: 0000000000000000 x18: 0000000000000000
>>> [=C2=A0 315.813276] x17: 0000000000000001 x16: 0000000000000019
>>> [=C2=A0 315.818578] x15: 000000148ccdabe2 x14: 0000000000000136
>>> [=C2=A0 315.823879] x13: 0000000000000001 x12: 00000000000003f8
>>> [=C2=A0 315.829180] x11: 0000000000000000 x10: 0000000000000000
>>> [=C2=A0 315.834482] x9 : ffff0000ff899990 x8 : ffff0000ff899000
>>> [=C2=A0 315.839784] x7 : 0000000040000000 x6 : 0000000000210d00
>>> [=C2=A0 315.845085] x5 : 0000000000000001 x4 : 0000000000000000
>>> [=C2=A0 315.850386] x3 : 00000000000000b0 x2 : 0000000000000001
>>> [=C2=A0 315.855687] x1 : 0000000000000000 x0 : 0000000000000001
>>> [=C2=A0 315.860988] Call trace:
>>> [=C2=A0 315.863432]=C2=A0 _raw_write_lock_irqsave+0xb0/0x2b8
>>> [=C2=A0 315.867956]=C2=A0 ida_free+0x48/0x158
>>> [=C2=A0 315.871184]=C2=A0 __media_device_unregister_entity+0x28/0xf0
>>> [=C2=A0 315.876402]=C2=A0 media_device_unregister+0x6c/0x148
>>> [=C2=A0 315.880927]=C2=A0 host1x_video_remove+0x20/0x48
>>> [=C2=A0 315.885021]=C2=A0 host1x_device_remove+0x1c/0x30
>>> [=C2=A0 315.889198]=C2=A0 device_release_driver_internal+0xf4/0x1c0
>>> [=C2=A0 315.894325]=C2=A0 device_driver_detach+0x14/0x20
>>> [=C2=A0 315.898503]=C2=A0 unbind_store+0xd4/0xf8
>>> [=C2=A0 315.901986]=C2=A0 drv_attr_store+0x20/0x30
>>> [=C2=A0 315.905645]=C2=A0 sysfs_kf_write+0x40/0x50
>>> [=C2=A0 315.909301]=C2=A0 kernfs_fop_write+0xf8/0x210
>>> [=C2=A0 315.913219]=C2=A0 __vfs_write+0x18/0x40
>>> [=C2=A0 315.916616]=C2=A0 vfs_write+0xdc/0x1c8
>>> [=C2=A0 315.919926]=C2=A0 ksys_write+0x68/0xf0
>>> [=C2=A0 315.923235]=C2=A0 __arm64_sys_write+0x18/0x20
>>> [=C2=A0 315.927154]=C2=A0 el0_svc_common.constprop.0+0x68/0x160
>>> [=C2=A0 315.931936]=C2=A0 do_el0_svc+0x20/0x80
>>> [=C2=A0 315.935246]=C2=A0 el0_sync_handler+0x10c/0x180
>>> [=C2=A0 315.939246]=C2=A0 el0_sync+0x140/0x180
>>> [=C2=A0 315.942560] Code: 8803fc02 35ffffa3 17fffda6 f9800071 (885ffc60=
)
>>> [=C2=A0 315.948644] ---[ end trace e42b943f3c1af06c ]---
>>>
>>> The following diff fixes this:
>>>
>>> ------------------ cut here ------------------
>>> diff --git a/drivers/staging/media/tegra/tegra-vi.c=20
>>> b/drivers/staging/media/tegra/tegra-vi.c
>>> index 9714152aa6a7..53cf37af9602 100644
>>> --- a/drivers/staging/media/tegra/tegra-vi.c
>>> +++ b/drivers/staging/media/tegra/tegra-vi.c
>>> @@ -583,7 +583,7 @@ static int tegra_channel_init(struct=20
>>> tegra_vi_channel *chan)
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* initialize the video_device */
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 chan->video->fops =3D &tegra_chann=
el_fops;
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 chan->video->v4l2_dev =3D &vid->v4=
l2_dev;
>>> -=C2=A0=C2=A0=C2=A0=C2=A0 chan->video->release =3D video_device_release=
_empty;
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 chan->video->release =3D video_device_release=
;
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 chan->video->queue =3D &chan->queu=
e;
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 snprintf(chan->video->name, sizeof=
(chan->video->name),=20
>>> "%s-%s-%u",
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0 dev_name(vi->dev), "output", chan->portno);
>>> @@ -647,6 +647,7 @@ static int tegra_channel_init(struct=20
>>> tegra_vi_channel *chan)
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 media_entity_cleanup(&chan->video-=
>entity);
>>> =C2=A0 release_vdev:
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 video_device_release(chan->video);
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 chan->video =3D NULL;
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return ret;
>>> =C2=A0 }
>>>
>>> @@ -707,7 +708,6 @@ static void tegra_vi_channels_cleanup(struct=20
>>> tegra_vi *vi)
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 mutex_lock(=
&chan->video_lock);
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 vb2_queue_r=
elease(&chan->queue);
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 mutex_unloc=
k(&chan->video_lock);
>>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 video_device_release(ch=
an->video);
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0 }
>>>
>>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0 if (chan->frame_start_sp)
>>> ------------------ cut here ------------------
>> Note: Sakari suggested to embed struct video_device into struct=20
>> tegra_vi_channel.
>> In that case chan->video->release should remain=20
>> video_device_release_empty and
>> all video_device_alloc()/release() calls would have to be dropped.
>
> Thanks Hans. Tried several unbind/unbind not sure why it did not repro=20
> during my testing.
>
> video device is also part of tegra_vi_channel. So, v6 will remove=20
> video_device_alloc and use video_device_release_empty like I had in v3.
>
> This should help fix crash during unbind.
>
>>
>> Regards,
>>
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Hans

With video device being part of the channel structure, it gets allocated=20
along with vi channel allocation during host1x vi client init and is=20
removed during channel free which happens during host1x vi client exit.

Wit this during driver unbind with video node kept opened with v4l2-ctl=20
sleep, it crashes during media_device_unregister_entity.

Using, separate video device allocation and freeing allocation during=20
video device release callback,=C2=A0 driver unbind works=C2=A0 as by the ti=
me of=20
entity unregister its it still available.

So, will keep allocating video device separately with video_device_alloc=20
and will use video_device_release call back in v6.