Re: [PATCH 4.19 50/54] drm/msm: stop abusing dma_map/unmap for cache

[Rob Clark <robdclark@chromium.org>]

On Tue, May 26, 2020 at 7:33 AM Naresh Kamboju
<naresh.kamboju@linaro.org> wrote:
>
> On Thu, 23 Apr 2020 at 05:03, <nobuhiro1.iwamatsu@toshiba.co.jp> wrote:
> <trim>
> >
> > I think the following patch is needed for this.
> >
> > 9f614197c744002f9968e82c649fdf7fe778e1e7
> > 3de433c5b38af49a5fc7602721e2ab5d39f1e69c
> >
> > But I have no environment to check this now.
>
> The above suggested two patches already in stable-rc 4.19 branch
> but i still notice Internal error: Oops: 96000144 [#1] PREEMPT SMP
> on arm64 qualcomm dragonboard-410c device while booting.
>
> [    7.906343] msm 1a00000.mdss: bound 1a98000.dsi (ops dsi_ops [msm])
> [    7.912697] adreno 1c00000.gpu: 1c00000.gpu supply vdd not found,
> using dummy regulator
> [    7.918567] adreno 1c00000.gpu: Linked as a consumer to regulator.0
> [    7.926521] adreno 1c00000.gpu: 1c00000.gpu supply vddcx not found,
> using dummy regulator
> [    7.932759] msm 1a00000.mdss: A306: using IOMMU
> [    7.941207] Unable to handle kernel paging request at virtual
> address ffffffff80000000
> [    7.945375] Mem abort info:
> [    7.953353]   ESR = 0x96000144
> [    7.956034]   Exception class = DABT (current EL), IL = 32 bits
> [    7.970501]   EA = 0, S1PTW = 0
> [    7.970516] Data abort info:
> [    7.972485]   ISV = 0, ISS = 0x00000144
> [    7.975577]   CM = 1, WnR = 1
> [    7.979169] swapper pgtable: 4k pages, 48-bit VAs, pgdp = (____ptrval____)
> [    7.982295] [ffffffff80000000] pgd=0000000000000000
> [    7.989099] Internal error: Oops: 96000144 [#1] PREEMPT SMP
> [    7.993802] Modules linked in: msm(+) crc32_ce adv7511 cec
> mdt_loader drm_kms_helper drm drm_panel_orientation_quirks fuse
> [    7.999367] Process systemd-udevd (pid: 2849, stack limit =
> 0x(____ptrval____))
> [    8.010474] CPU: 1 PID: 2849 Comm: systemd-udevd Not tainted
> 4.19.125-rc1-00077-g0708fb235b9c #1
> [    8.017677] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
> [    8.026703] pstate: 80000005 (Nzcv daif -PAN -UAO)
> [    8.033390] pc : __clean_dcache_area_poc+0x20/0x38
> [    8.037998] lr : __swiotlb_sync_sg_for_device+0x74/0xa0
> [    8.038001] sp : ffff00000e313490
> [    8.038004] x29: ffff00000e313490 x28: 0000000000000001
> [    8.038009] x27: ffff000000d56e40 x26: ffff800036301000
> [    8.038013] x25: ffff80003c108410 x24: ffff000009069998
> [    8.038018] x23: ffff80003c108810 x22: 0000000000000000
> [    8.038023] x21: 0000000000000001 x20: 0000000000000001
> [    8.038027] x19: ffff80003acd4480 x18: ffff0000092298c8
> [    8.038032] x17: 0000000000000000 x16: 0000000000000000
> [    8.038036] x15: 0000000000000010 x14: ffffffffffffffff
> [    8.038042] x13: ffff0000893987d7 x12: 0000000000000000
> [    8.038046] x11: 0000800036c56000 x10: ffff8000362ef368
> [    8.038050] x9 : 0000000000001000 x8 : ffff7e0000e71640
> [    8.038055] x7 : 0000000000000001 x6 : 0000000000000000
> [    8.038059] x5 : 0000000000000000 x4 : ffffffff80000000
> [    8.038064] x3 : 000000000000003f x2 : 0000000000000040
> [    8.038068] x1 : ffffffff80001000 x0 : ffffffff80000000
> [    8.038072] Call trace:
> [    8.038078]  __clean_dcache_area_poc+0x20/0x38
> [    8.038204]  get_pages+0x1cc/0x240 [msm]
> [    8.038327]  msm_gem_get_iova+0x94/0x138 [msm]
> [    8.141741]  _msm_gem_kernel_new+0x40/0xb0 [msm]
> [    8.145989]  msm_gem_kernel_new+0x10/0x18 [msm]
> [    8.150759]  msm_gpu_init+0x300/0x568 [msm]
> [    8.155004]  adreno_gpu_init+0x14c/0x268 [msm]
> [    8.159171]  a3xx_gpu_init+0x7c/0x108 [msm]
> [    8.163682]  adreno_bind+0x144/0x238 [msm]
> [    8.167676]  component_bind_all+0x110/0x278
> [    8.171939]  msm_drm_bind+0x104/0x760 [msm]
> [    8.175921]  try_to_bring_up_master+0x14c/0x1b0
> [    8.180086]  component_master_add_with_match+0xc0/0x100
> [    8.184697]  msm_pdev_probe+0x280/0x320 [msm]
> [    8.189810]  platform_drv_probe+0x50/0xa0
> [    8.194322]  really_probe+0x1f4/0x290
> [    8.198314]  driver_probe_device+0x54/0xe8
> [    8.201960]  __driver_attach+0xe0/0xe8
> [    8.205952]  bus_for_each_dev+0x70/0xb8
> [    8.209685]  driver_attach+0x20/0x28
> [    8.213417]  bus_add_driver+0x1a0/0x210
> [    8.217237]  driver_register+0x60/0x110
> [    8.220797]  __platform_driver_register+0x44/0x50
> [    8.224717]  msm_drm_register+0x54/0x68 [msm]
> [    8.229479]  do_one_initcall+0x54/0x154
> [    8.233819]  do_init_module+0x54/0x1c8
> [    8.237463]  load_module+0x1bf4/0x2190
> [    8.241282]  __se_sys_finit_module+0xb8/0xc8
> [    8.245016]  __arm64_sys_finit_module+0x18/0x20
> [    8.249445]  el0_svc_common+0x70/0x168
> [    8.253695]  el0_svc_handler+0x2c/0x80
> [    8.257514]  el0_svc+0x8/0xc
> [    8.261250] Code: 9ac32042 8b010001 d1000443 8a230000 (d50b7e20)
> [    8.264290] ---[ end trace 2effae58ca65f06b ]---
>
> on stable-rc 4.19 branch git log show this info,
> $ git log  --oneline drivers/gpu/drm/msm/msm_gem.c | head
> 05fe33cad985 drm/msm: Use the correct dma_sync calls harder
> 39718d086d9b drm/msm: Use the correct dma_sync calls in msm_gem
> 9c23e00804f8 drm/msm: stop abusing dma_map/unmap for cache
> a5f74ec7d3cb gpu: drm: msm: Change return type to vm_fault_t
> 3976626ea3d2 drm/msm: Fix possible null dereference on failure of get_pages()
> d71b6bd80d96 drm/msm/dsi: fix direct caller of msm_gem_free_object()
> dc9a9b32053e drm/msm: Replace gem_object deprecated functions
> 62e3a3e342af drm/msm: fix leak in failed get_pages
> 7a88cbd8d65d Backmerge tag 'v4.14-rc7' into drm-next
> fad33f4b1073 drm/msm: add special _get_vaddr_active() for cmdstream dumps
>
> link to full boot log,
> https://qa-reports.linaro.org/lkft/linux-stable-rc-4.19-oe/build/v4.19.124-77-g0708fb235b9c/testrun/1450572/log
> https://qa-reports.linaro.org/lkft/linux-stable-rc-4.19-oe/build/v4.19.124-77-g0708fb235b9c/testrun/1450572
>
> Kernel config:
> https://builds.tuxbuild.com/Xp5Fh9e52QxohQeW6nazPA/kernel.config

I suspect there is some difference between qcom_iommu and arm-smmu?
Maybe qcom_iommu (esp. back in v4.19) is missing something for
automatic hookup of iommu-dma-ops?

All the ugliness around dma-sync is related to trying to avoid using
dma_map_*/dma_unmap_* when arm-smmu is in use (and the iommu dma-ops
are installed, since they end up fighting w/ drm/msm's direct use of
it's iommus).  It looks like we are going to finally get a way to
solve this uglyness a bit better once some arm-smmu patches[1] land in
v5.8.  I suppose that doesn't really help v4.19.

But taking a step back, I'm not entirely sure whether this was a
problem yet on v4.19.  Presumably dropping these would make db410c
(qcom_iommu) work:

  05fe33cad985 drm/msm: Use the correct dma_sync calls harder
  39718d086d9b drm/msm: Use the correct dma_sync calls in msm_gem
  9c23e00804f8 drm/msm: stop abusing dma_map/unmap for cache

What I'm not entirely sure of (v4.19 seems so long ago now) is whether
that would cause problems for db820c (arm-smmu)?  Looks like the first
of those patches landed around v5.4, so presumably the problem it was
meant to workaround started happening sometime after v4.19?

BR,
-R

[1] https://lkml.org/lkml/2020/4/20/1142

> >
> > Best regards,
> >   Nobuhiro
> > >
> > > --
> > > Linaro LKFT
> > > https://lkft.linaro.org