[PATCH 0/5] Unmappable DRM client buffers for fbdev emulation

[Thomas Zimmermann]

Hi

Am 04.07.19 um 16:15 schrieb Noralf Trønnes:
>>> Hm, why do you think that?
>>
>> Drivers may already come with their own shadow buffer. Cirrus is an
>> example of that. It uses shmem buffer objects as shadow fbs and
>> internally updates the device frame buffer in its dirty callback. Using
>> dirty() to select the shadow fbdev adds another buffer (and another
>> memcpy) for no reason.
> 
> Cirruc uses shmem buffers and they won't work with fbdev defio (both use
> page->lru). shmem is the reason I added shadow buffering to generic
> fbdev in the first place. It will now work with whatever backing buffer
> the driver uses, as long as it can provide a virtual address on the dumb
> buffer (not the case with rockchip for instance, due to limited virtual
> address space).

OK, I see. Thanks or clarifying.

Best regards
Thomas

> Noralf.
> 
>>
>> Best regards
>> Thomas
>>
>>> The thing with fbdev defio is that it only supports kmalloc and vmalloc
>>> allocated memory (page->lru is avail.). This means that only the CMA
>>> drivers can use defio without shadow memory. To keep things simple
>>> everyone with a dirty() callback gets a shadow buffer.
>>>
>>> Noralf.
>>>
>>>> Best regards
>>>> Thomas
>>>>
>>>>> Really nice diffstat by the way :-)
>>>>>
>>>>> Noralf.
>>>>>
>>>>>> [1] https://lists.freedesktop.org/archives/dri-devel/2019-June/224423.html
>>>>>>
>>>>>> Thomas Zimmermann (5):
>>>>>>   drm/client: Support unmapping of DRM client buffers
>>>>>>   drm/fb-helper: Unmap BO for shadow-buffered framebuffer console
>>>>>>   drm/ast: Replace struct ast_fbdev with generic framebuffer emulation
>>>>>>   drm/bochs: Use shadow buffer for bochs framebuffer console
>>>>>>   drm/mgag200: Replace struct mga_fbdev with generic framebuffer
>>>>>>     emulation
>>>>>>
>>>>>>  drivers/gpu/drm/ast/Makefile           |   2 +-
>>>>>>  drivers/gpu/drm/ast/ast_drv.c          |  22 +-
>>>>>>  drivers/gpu/drm/ast/ast_drv.h          |  17 --
>>>>>>  drivers/gpu/drm/ast/ast_fb.c           | 341 -------------------------
>>>>>>  drivers/gpu/drm/ast/ast_main.c         |  30 ++-
>>>>>>  drivers/gpu/drm/ast/ast_mode.c         |  21 --
>>>>>>  drivers/gpu/drm/bochs/bochs_kms.c      |   2 +-
>>>>>>  drivers/gpu/drm/drm_client.c           |  71 ++++-
>>>>>>  drivers/gpu/drm/drm_fb_helper.c        |  14 +-
>>>>>>  drivers/gpu/drm/mgag200/Makefile       |   2 +-
>>>>>>  drivers/gpu/drm/mgag200/mgag200_drv.h  |  19 --
>>>>>>  drivers/gpu/drm/mgag200/mgag200_fb.c   | 309 ----------------------
>>>>>>  drivers/gpu/drm/mgag200/mgag200_main.c |  61 +++--
>>>>>>  drivers/gpu/drm/mgag200/mgag200_mode.c |  27 --
>>>>>>  include/drm/drm_client.h               |   3 +
>>>>>>  15 files changed, 154 insertions(+), 787 deletions(-)
>>>>>>  delete mode 100644 drivers/gpu/drm/ast/ast_fb.c
>>>>>>  delete mode 100644 drivers/gpu/drm/mgag200/mgag200_fb.c
>>>>>>
>>>>>> --
>>>>>> 2.21.0
>>>>>>
>>>>> _______________________________________________
>>>>> dri-devel mailing list
>>>>> dri-devel at lists.freedesktop.org
>>>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>>>>
>>>>
>>
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-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)

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