Re: [PATCH] drm/msm: Call shutdown conditionally

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Jan 19, 2021 at 10:49 PM Fabio Estevam <festevam@gmail.com> wrote:
>
> Hi Daniel,
>
> On Tue, Jan 19, 2021 at 3:01 PM Daniel Vetter <daniel@ffwll.ch> wrote:
>
> > Don't we need the same treatment for suspend/resume too? Also if you
>
> Yes, you are right. I have just tested suspend/resume and the problem
> is there too:
>
> [   69.708552] 8<--- cut here ---
> [   69.711970] Unable to handle kernel NULL pointer dereference at
> virtual address 00000000
> [   69.720240] pgd = (ptrval)
> [   69.723000] [00000000] *pgd=ca217831
> [   69.726664] Internal error: Oops: 17 [#1] SMP ARM
> [   69.731387] Modules linked in:
> [   69.734463] CPU: 0 PID: 167 Comm: sh Not tainted
> 5.11.0-rc3-next-20210118-dirty #383
> [   69.742223] Hardware name: Freescale i.MX53 (Device Tree Support)
> [   69.748326] PC is at msm_atomic_commit_tail+0x50/0xb90
> [   69.753505] LR is at commit_tail+0x9c/0x18c
> [   69.757705] pc : [<c07755f0>]    lr : [<c06e7218>]    psr: 60000013
> [   69.763982] sp : c28bfcd8  ip : fffffffa  fp : c24c20a0
> [   69.769217] r10: c0f82720  r9 : 00000010  r8 : 3a62b298
> [   69.774452] r7 : c23a3000  r6 : c2816c00  r5 : 00000000  r4 : 00000000
> [   69.780990] r3 : c24c2c00  r2 : 00000000  r1 : 00000000  r0 : 00000000
> [   69.787529] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
> [   69.794679] Control: 10c5387d  Table: 72870019  DAC: 00000051
> [   69.800434] Process sh (pid: 167, stack limit = 0x(ptrval))
> [   69.806019] Stack: (0xc28bfcd8 to 0xc28c0000)
> [   69.810391] fcc0:
>     ffffffff 20bfa1e1
> [   69.818584] fce0: 00000010 00000000 8a7c54c5 00000000 00000000
> c2816c00 00000000 c23a3000
> [   69.826778] fd00: 00000000 3a62b298 00000010 c0f82720 c24c20a0
> c06e7218 00000000 c2816c00
> [   69.834972] fd20: c23a3000 00000000 c2816c2c c16093d4 c17682f0
> c0e2920c 00000000 00000000
> [   69.843166] fd40: 00000000 c12ca028 c23a3000 c23a3494 c2816c00
> c23a349c c24c2010 c06e74d4
> [   69.851359] fd60: 00000000 c23a3000 c2816480 c07050ec c24c2010
> c0e2943c c1609798 c296a880
> [   69.859552] fd80: 00000009 00000001 00000000 00000000 c175f454
> 00000000 c175f458 c1c669cc
> [   69.867745] fda0: 00000000 c12c9acc 00000000 00000001 00000009
> 00000000 c23a32e4 c23a32e4
> [   69.875938] fdc0: 00000000 c1609388 c28be000 c23a3000 c28be000
> c1765220 c17682f0 c06e84bc
> [   69.884132] fde0: c24c2138 c28be000 c1765220 c07e9f58 00000010
> c176833c 00000002 c0777850
> [   69.892326] fe00: 00000000 c1e08a9c 00000002 00000010 396ed042
> 00000001 c1e08ac0 00000000
> [   69.900519] fe20: 00000000 c07ea57c c296ae28 c0e33ba0 00000000
> c1e08a9c 00000003 c125a7c8
> [   69.908714] fe40: c17fa154 c01954a8 c16093d4 00000001 c1e08ac0
> 00000000 00000000 c1609388
> [   69.916907] fe60: c28bfe74 00000003 00000000 c125a7c8 c17fa154
> 00000001 c1e08ac0 00000000
> [   69.925100] fe80: 00000000 c01963a4 00000003 c2a9f040 00000003
> 00000004 c1254a00 c01943b0
> [   69.933294] fea0: 00000004 c2901f10 c2a9f040 c2901f00 00d220f0
> c28bff78 00000000 c0374f0c
> [   69.941488] fec0: 00000000 00000000 00d220f0 c29488c0 00000000
> 00000004 00d220f0 c28bff78
> [   69.949681] fee0: c02c31c4 c0374e00 c2803000 c02c2bfc 00000001
> 00000000 c02c31c4 c2943bd0
> [   69.957876] ff00: c02e7428 c17ee19c c296adc8 00000000 c2943bd0
> c0183a34 c2943bd0 c02e7428
> [   69.966070] ff20: c28be000 c296a880 c1609798 c018ced8 c296adc8
> c0e33ba0 c17ee2de 60000013
> [   69.974264] ff40: 00000000 00000001 00000000 c1609388 c17ee2de
> c29488c0 c29488c0 00d220f0
> [   69.982457] ff60: 00000004 00000000 00000000 00000004 00d20284
> c02c31c4 00000000 00000000
> [   69.990651] ff80: c010019c c1609388 c1609798 00000001 00000000
> 000d7b54 00000004 c0100264
> [   69.998844] ffa0: c28be000 c0100080 00000001 00000000 00000001
> 00d220f0 00000004 00000000
> [   70.007039] ffc0: 00000001 00000000 000d7b54 00000004 00000004
> 00000020 00d20410 00d20284
> [   70.015232] ffe0: 000d7258 be831960 0001b93c b6ee97a0 60000010
> 00000001 00000000 00000000
> [   70.023427] [<c07755f0>] (msm_atomic_commit_tail) from [<c06e7218>]
> (commit_tail+0x9c/0x18c)
> [   70.031890] [<c06e7218>] (commit_tail) from [<c0e2920c>]
> (drm_atomic_helper_commit+0x1a0/0x1d4)
> [   70.040627] [<c0e2920c>] (drm_atomic_helper_commit) from
> [<c06e74d4>] (drm_atomic_helper_disable_all+0x1c4/0x1d4)
> [   70.050913] [<c06e74d4>] (drm_atomic_helper_disable_all) from
> [<c0e2943c>] (drm_atomic_helper_suspend+0xb8/0x170)
> [   70.061198] [<c0e2943c>] (drm_atomic_helper_suspend) from
> [<c06e84bc>] (drm_mode_config_helper_suspend+0x24/0x58)
> [   70.071486] [<c06e84bc>] (drm_mode_config_helper_suspend) from
> [<c07e9f58>] (dpm_prepare+0x1ac/0x7b0)
> [   70.080738] [<c07e9f58>] (dpm_prepare) from [<c07ea57c>]
> (dpm_suspend_start+0x20/0x98)
> [   70.088679] [<c07ea57c>] (dpm_suspend_start) from [<c01954a8>]
> (suspend_devices_and_enter+0xfc/0xcb8)
> [   70.097931] [<c01954a8>] (suspend_devices_and_enter) from
> [<c01963a4>] (pm_suspend+0x340/0x3e8)
> [   70.106651] [<c01963a4>] (pm_suspend) from [<c01943b0>]
> (state_store+0x68/0xc8)
> [   70.113982] [<c01943b0>] (state_store) from [<c0374f0c>]
> (kernfs_fop_write+0x10c/0x22c)
> [   70.122016] [<c0374f0c>] (kernfs_fop_write) from [<c02c2bfc>]
> (vfs_write+0xc4/0x53c)
> [   70.129795] [<c02c2bfc>] (vfs_write) from [<c02c31c4>] (ksys_write+0x60/0xec)
> [   70.136952] [<c02c31c4>] (ksys_write) from [<c0100080>]
> (ret_fast_syscall+0x0/0x2c)
> [   70.144630] Exception stack(0xc28bffa8 to 0xc28bfff0)
> [   70.149697] ffa0:                   00000001 00000000 00000001
> 00d220f0 00000004 00000000
> [   70.157891] ffc0: 00000001 00000000 000d7b54 00000004 00000004
> 00000020 00d20410 00d20284
> [   70.166083] ffe0: 000d7258 be831960 0001b93c b6ee97a0
> [   70.171156] Code: 1592208c 1184421c e1530000 1afffff8 (e595c000)
> [   70.177483] ---[ end trace 2775110cb98281db ]---
>
> > feel like follow up patch to push this into the helpers with a
> > DRIVER_MODESET check like I described would be kinda neat.
>
> I tried using use drm_core_check_feature(dev, DRIVER_MODESET), but
> since the drivers/gpu/drm/imx/imx-drm-core.c also sets the
> DRIVER_MODESET flag, I am not sure how we can differentiate the fact
> that imx5 is not running on a Qualcomm display driver.

If you set struct drm_device.driver_features = ~DRIVER_MODESET then
that should work (see the kerneldoc in the header). Latest this needs
to be done before drm_dev_register, and I guess you could use the same
check right there you use here. But Rob has probably an idea that fits
even cleaner.

Also note that I think we have 5 helper functions that would need have
the new check: drm_atomic_helper_suspend/resume/shutdown and
drm_mode_config_helper_suspend/resume.

> Just to be clear: would it be OK to proceed with this original patch
> as a minimum fix so that it can reach upstream and also stable-trees
> (5.4 and 5.10)?

Well with the suspend/resume fixed I think this one here is fine. See
the functions you need to search for above in msm code, same check as
in shutdown should work there too.

> I am glad to work on a more generic solution that would also fix the
> suspend/resume case. Just need some more guidance on that as I am not
> familiar with this area.

I'm always to help out to get a few nice patches landed!

Cheers, Daniel

>
> Thanks,
>
> Fabio Estevam



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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