Re: [RFC][PATCH v2 0/4] Support GEM object mappings from I/O memory

[Thomas Zimmermann <tzimmermann@suse.de>]

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cc'ing TTM maintainers for comments. We might want to use the I/O
pointer structure with TTM at some point.

Am 06.08.20 um 10:52 schrieb Thomas Zimmermann:
> DRM's fbdev console uses regular load and store operations to update
> framebuffer memory. The bochs driver on sparc64 requires the use of
> I/O-specific load and store operations. We have a workaround, but need
> a long-term solution to the problem. Previous attempts to resolve the
> issue returned an extra is_iomem flag from vmap(), or added a separate
> vmap_iomem() callback to GEM objects.
> 
> This patchset is yet another iteration with a different idea. Instead
> of a raw pointer, vmap() interfaces now return a structure that contains
> the buffer address in system or I/O memory, plus a flag that signals
> which location the address is in.
> 
> Patch #1 updates the vboxvideo driver to match the latest VRAM helpers.
> This simplifies the other patches and should be merged in any case.
> 
> Patch #2 adds struct drm_gem_membuf, which contains the pointer and flag,
> and converts the generic GEM interfaces to use it.
> 
> Patch #3 converts vmap/vunmap in GEM object functions and updates most
> GEM backends. A few drivers are still missing, but the patch should be
> acceptable for an RFC.
> 
> Patch #4 changes fbdev helpers to access framebuffer memory either with
> system or I/O memcpy functions.
> 
> Thomas Zimmermann (4):
>   drm/vboxvideo: Use drm_gem_vram_vmap() interfaces
>   drm/gem: Update client API to use struct drm_gem_membuf
>   drm/gem: Use struct drm_gem_membuf in vmap op and convert GEM backends
>   drm/fb_helper: Access framebuffer as I/O memory, if required
> 
>  drivers/gpu/drm/ast/ast_cursor.c       |  29 ++-
>  drivers/gpu/drm/ast/ast_drv.h          |   2 +-
>  drivers/gpu/drm/bochs/bochs_kms.c      |   1 -
>  drivers/gpu/drm/drm_client.c           |  25 ++-
>  drivers/gpu/drm/drm_fb_helper.c        | 246 ++++++++++++++++++++++---
>  drivers/gpu/drm/drm_gem.c              |  28 +--
>  drivers/gpu/drm/drm_gem_cma_helper.c   |  15 +-
>  drivers/gpu/drm/drm_gem_shmem_helper.c |  31 ++--
>  drivers/gpu/drm/drm_gem_vram_helper.c  | 142 +++++---------
>  drivers/gpu/drm/drm_internal.h         |   5 +-
>  drivers/gpu/drm/drm_prime.c            |  16 +-
>  drivers/gpu/drm/mgag200/mgag200_mode.c |  11 +-
>  drivers/gpu/drm/qxl/qxl_display.c      |  12 +-
>  drivers/gpu/drm/qxl/qxl_draw.c         |  14 +-
>  drivers/gpu/drm/qxl/qxl_drv.h          |   6 +-
>  drivers/gpu/drm/qxl/qxl_object.c       |  19 +-
>  drivers/gpu/drm/qxl/qxl_object.h       |   2 +-
>  drivers/gpu/drm/qxl/qxl_prime.c        |  12 +-
>  drivers/gpu/drm/tiny/cirrus.c          |  15 +-
>  drivers/gpu/drm/tiny/gm12u320.c        |  12 +-
>  drivers/gpu/drm/udl/udl_modeset.c      |  10 +-
>  drivers/gpu/drm/vboxvideo/vbox_mode.c  |  17 +-
>  include/drm/drm_client.h               |   7 +-
>  include/drm/drm_device.h               |  26 +++
>  include/drm/drm_gem.h                  |   5 +-
>  include/drm/drm_gem_cma_helper.h       |   4 +-
>  include/drm/drm_gem_shmem_helper.h     |   4 +-
>  include/drm/drm_gem_vram_helper.h      |   9 +-
>  include/drm/drm_mode_config.h          |  12 --
>  29 files changed, 464 insertions(+), 273 deletions(-)
> 
> --
> 2.28.0
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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