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

[Thomas Zimmermann]

Hi

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.

On top of these patches, I have a patch set that provides a single
init/release interface for TTM global data. I'll post it when the
current patches got some feed back.

I'd really like to move the code from drm_global.c back into TTM. It's
TTM-specific and not useful elsewhere. However, the first commit message
from 2010 [1] says that some unnamed, external driver uses this code for
something. Do you know if this still applies?

Best regards
Thomas

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ba4420c224c2808f2661cf8428f43ceef7a73a4a

> 
> 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
>>
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstr. 5, D-90409 Nürnberg
Tel: +49-911-74053-0; Fax: +49-911-7417755;  https://www.suse.com/
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard,
Graham Norton, HRB 21284 (AG Nürnberg)

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