[PATCH 0/2] Provide init/release functions for struct ttm_bo_global

[Christian König]

Hi Thomas,

Am 30.08.2018 um 08:34 schrieb Thomas Zimmermann:
> Hi Christian,
>
> I just wanted to ask if there's something else required to get this
> patch set reviewed and landed.

I just need to find some time to review them.

> On top of these two patches, I have a patch set that replaces the
> driver-specific global-bo-and-mem combos with a single struct ttm_global
> structure. It further merges struct drm_global into struct ttm_global
> and implements it such that drivers can either share the global memory

That sounds good.

> or create their private instance.

That doesn't sounds good. Drivers should not be allowed to create their 
own private instance of that.

Thanks for doing this,
Christian.

>   It's also a step towards drm device
> hotplug, which someone just asked.
>
> Best regards
> Thomas
>
>
> Am 13.08.2018 um 12:33 schrieb Christian König:
>> Yes, please! I had it on my TODO list to clean that up for an eternity.
>>
>> Actually I never understood why that should be driver work to setup TTM?
>>
>> I mean can't we just have a module_init/module_exit for TTM?
>>
>> Thanks,
>> Christian.
>>
>> Am 13.08.2018 um 12:24 schrieb Thomas Zimmermann:
>>> TTM uses global memory and BO for backing graphics buffers. These are
>>> represented by struct ttm_mem_global and struct ttm_bo_global.
>>>
>>> Currently, struct ttm_bo_global can only be initialized and released
>>> through
>>> struct ttm_bo_global_ref. This is a workaround for passing an instance of
>>> ttm_mem_global to the BO global initialization code.
>>>
>>> The use of struct ttm_bo_global_ref makes driver code unnecessary hard to
>>> understand. At the same time drivers can use any combination of memory
>>> and
>>> BO for initializing the global instances. This can result in subtle bugs
>>> when the order of initializing and releasing drivers changes.
>>>
>>> As a first step for resolving these problems, the provided patch set
>>> separates initialization and release of struct ttm_bo_global from
>>> struct ttm_bo_global_ref.
>>>
>>> The first patch only renames ttm_bo_global_{init/release}. Hopefully this
>>> change can be applied at once for all drivers.
>>>
>>> Future directions: All TTM-based drivers follow the same pattern for
>>> setting
>>> up the TTM. In a follow-up patch, this code can be moved into a single
>>> place
>>> and shared among drivers.
>>>
>>> Thomas Zimmermann (2):
>>>     drm/ttm: Rename ttm_bo_global_{init,release}() to
>>>       ttm_bo_global_ref_*()
>>>     drm/ttm: Provide ttm_bo_global_{init/release}() for struct
>>>       ttm_bo_global
>>>
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c     |  4 +-
>>>    drivers/gpu/drm/ast/ast_ttm.c               |  4 +-
>>>    drivers/gpu/drm/bochs/bochs_mm.c            |  4 +-
>>>    drivers/gpu/drm/cirrus/cirrus_ttm.c         |  4 +-
>>>    drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c |  4 +-
>>>    drivers/gpu/drm/mgag200/mgag200_ttm.c       |  4 +-
>>>    drivers/gpu/drm/nouveau/nouveau_ttm.c       |  4 +-
>>>    drivers/gpu/drm/qxl/qxl_ttm.c               |  4 +-
>>>    drivers/gpu/drm/radeon/radeon_ttm.c         |  4 +-
>>>    drivers/gpu/drm/ttm/ttm_bo.c                | 12 ++---
>>>    drivers/gpu/drm/virtio/virtgpu_ttm.c        |  4 +-
>>>    drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c    |  4 +-
>>>    drivers/staging/vboxvideo/vbox_ttm.c        |  4 +-
>>>    include/drm/ttm/ttm_bo_driver.h             | 53 ++++++++++++++++-----
>>>    14 files changed, 70 insertions(+), 43 deletions(-)
>>>
>>> -- 
>>> 2.18.0
>>>