Re: [PATCH 0/2] Lima DRM driver

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 07.02.19 um 10:09 schrieb Daniel Vetter:
> On Wed, Feb 06, 2019 at 09:14:55PM +0800, Qiang Yu wrote:
>> Kernel DRM driver for ARM Mali 400/450 GPUs.
>>
>> Since last RFC, all feedback has been addressed. Most Mali DTS
>> changes are already upstreamed by SoC maintainers. The kernel
>> driver and user-kernel interface are quite stable for several
>> months, so I think it's ready to be upstreamed.
>>
>> This implementation mainly take amdgpu DRM driver as reference.
>>
>> - Mali 4xx GPUs have two kinds of processors GP and PP. GP is for
>>    OpenGL vertex shader processing and PP is for fragment shader
>>    processing. Each processor has its own MMU so prcessors work in
>>    virtual address space.
>> - There's only one GP but multiple PP (max 4 for mali 400 and 8
>>    for mali 450) in the same mali 4xx GPU. All PPs are grouped
>>    togather to handle a single fragment shader task divided by
>>    FB output tiled pixels. Mali 400 user space driver is
>>    responsible for assign target tiled pixels to each PP, but mali
>>    450 has a HW module called DLBU to dynamically balance each
>>    PP's load.
>> - User space driver allocate buffer object and map into GPU
>>    virtual address space, upload command stream and draw data with
>>    CPU mmap of the buffer object, then submit task to GP/PP with
>>    a register frame indicating where is the command stream and misc
>>    settings.
>> - There's no command stream validation/relocation due to each user
>>    process has its own GPU virtual address space. GP/PP's MMU switch
>>    virtual address space before running two tasks from different
>>    user process. Error or evil user space code just get MMU fault
>>    or GP/PP error IRQ, then the HW/SW will be recovered.
>> - Use TTM as MM. TTM_PL_TT type memory is used as the content of
>>    lima buffer object which is allocated from TTM page pool. all
>>    lima buffer object gets pinned with TTM_PL_FLAG_NO_EVICT when
>>    allocation, so there's no buffer eviction and swap for now.
> All other render gpu drivers that have unified memory (aka is on the SoC)
> use GEM directly, with some of the helpers we have. So msm, etnaviv, vc4
> (and i915 is kinda the same too really). TTM makes sense if you have some
> discrete memory to manage, but imo not in any other place really.
>
> What's the design choice behind this?

Agree that this seems unnecessary complicated.

Additional to that why do you use TTM_PL_FLAG_NO_EVICT? That is a 
serious show stopper and as far as I can of hand see completely unnecessary.

Christian.

>
>  From an upstream pov having all soc gpu drivers use similar approaches
> should help with shared infrastructure and stuff like that.
>
> Another one: What's the plan with extending this to panfrost? Or are the
> architectures for command submission totally different, and we'll need
> separate kernel drivers for utgard/midgard/bifrost?
>
> Thanks, Daniel
>
>> - Use drm_sched for GPU task schedule. Each OpenGL context should
>>    have a lima context object in the kernel to distinguish tasks
>>    from different user. drm_sched gets task from each lima context
>>    in a fair way.
>>
>> This patch serial is based on 5.0-rc5 and squash all the commits.
>> For whole history of this driver's development, see:
>> https://gitlab.freedesktop.org/lima/linux/commits/lima-5.0-rc5
>> https://gitlab.freedesktop.org/lima/linux/commits/lima-4.17-rc4
>>
>> Mesa driver is still in development and not ready for daily usage,
>> but can run some simple tests like kmscube and glamrk2, and some
>> single full screen application like kodi-gbm, see:
>> https://gitlab.freedesktop.org/lima/mesa
>>
>> [rfc]
>> https://lists.freedesktop.org/archives/dri-devel/2018-May/177314.html
>>
>> Lima Project Developers (1):
>>    drm/lima: driver for ARM Mali4xx GPUs
>>
>> Qiang Yu (1):
>>    drm/fourcc: add ARM tiled format modifier
>>
>>   drivers/gpu/drm/Kconfig               |   2 +
>>   drivers/gpu/drm/Makefile              |   1 +
>>   drivers/gpu/drm/lima/Kconfig          |  10 +
>>   drivers/gpu/drm/lima/Makefile         |  22 ++
>>   drivers/gpu/drm/lima/lima_bcast.c     |  46 +++
>>   drivers/gpu/drm/lima/lima_bcast.h     |  14 +
>>   drivers/gpu/drm/lima/lima_ctx.c       | 124 +++++++
>>   drivers/gpu/drm/lima/lima_ctx.h       |  33 ++
>>   drivers/gpu/drm/lima/lima_device.c    | 384 ++++++++++++++++++++
>>   drivers/gpu/drm/lima/lima_device.h    | 116 ++++++
>>   drivers/gpu/drm/lima/lima_dlbu.c      |  56 +++
>>   drivers/gpu/drm/lima/lima_dlbu.h      |  18 +
>>   drivers/gpu/drm/lima/lima_drv.c       | 459 ++++++++++++++++++++++++
>>   drivers/gpu/drm/lima/lima_drv.h       |  59 ++++
>>   drivers/gpu/drm/lima/lima_gem.c       | 485 +++++++++++++++++++++++++
>>   drivers/gpu/drm/lima/lima_gem.h       |  25 ++
>>   drivers/gpu/drm/lima/lima_gem_prime.c | 144 ++++++++
>>   drivers/gpu/drm/lima/lima_gem_prime.h |  18 +
>>   drivers/gpu/drm/lima/lima_gp.c        | 280 +++++++++++++++
>>   drivers/gpu/drm/lima/lima_gp.h        |  16 +
>>   drivers/gpu/drm/lima/lima_l2_cache.c  |  79 +++++
>>   drivers/gpu/drm/lima/lima_l2_cache.h  |  14 +
>>   drivers/gpu/drm/lima/lima_mmu.c       | 135 +++++++
>>   drivers/gpu/drm/lima/lima_mmu.h       |  16 +
>>   drivers/gpu/drm/lima/lima_object.c    | 103 ++++++
>>   drivers/gpu/drm/lima/lima_object.h    |  72 ++++
>>   drivers/gpu/drm/lima/lima_pmu.c       |  61 ++++
>>   drivers/gpu/drm/lima/lima_pmu.h       |  12 +
>>   drivers/gpu/drm/lima/lima_pp.c        | 419 ++++++++++++++++++++++
>>   drivers/gpu/drm/lima/lima_pp.h        |  19 +
>>   drivers/gpu/drm/lima/lima_regs.h      | 298 ++++++++++++++++
>>   drivers/gpu/drm/lima/lima_sched.c     | 486 ++++++++++++++++++++++++++
>>   drivers/gpu/drm/lima/lima_sched.h     | 108 ++++++
>>   drivers/gpu/drm/lima/lima_ttm.c       | 319 +++++++++++++++++
>>   drivers/gpu/drm/lima/lima_ttm.h       |  24 ++
>>   drivers/gpu/drm/lima/lima_vm.c        | 354 +++++++++++++++++++
>>   drivers/gpu/drm/lima/lima_vm.h        |  59 ++++
>>   include/uapi/drm/drm_fourcc.h         |   9 +
>>   include/uapi/drm/lima_drm.h           | 193 ++++++++++
>>   39 files changed, 5092 insertions(+)
>>   create mode 100644 drivers/gpu/drm/lima/Kconfig
>>   create mode 100644 drivers/gpu/drm/lima/Makefile
>>   create mode 100644 drivers/gpu/drm/lima/lima_bcast.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_bcast.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_ctx.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_ctx.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_device.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_device.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_dlbu.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_dlbu.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_drv.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_drv.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_gem.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_gem.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_gem_prime.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_gem_prime.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_gp.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_gp.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_l2_cache.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_l2_cache.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_mmu.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_mmu.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_object.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_object.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_pmu.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_pmu.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_pp.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_pp.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_regs.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_sched.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_sched.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_ttm.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_ttm.h
>>   create mode 100644 drivers/gpu/drm/lima/lima_vm.c
>>   create mode 100644 drivers/gpu/drm/lima/lima_vm.h
>>   create mode 100644 include/uapi/drm/lima_drm.h
>>
>> -- 
>> 2.17.1
>>

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