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Date:   Fri, 28 Jan 2022 10:48:42 +0100
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Subject: Re: [PATCH 00/14] Rename dma-buf-map
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To:     Lucas De Marchi <lucas.demarchi@intel.com>
Cc:     linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        srinivas.kandagatla@linaro.org, gregkh@linuxfoundation.org,
        sumit.semwal@linaro.org, daniel.vetter@ffwll.ch, airlied@linux.ie,
        lyude@redhat.com, tzimmermann@suse.de, linux-media@vger.kernel.org,
        nouveau@lists.freedesktop.org
References: <20220128083626.3012259-1-lucas.demarchi@intel.com>
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 <20220128091213.qaq6v4vbeerzvd3f@ldmartin-desk2>
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From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
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Am 28.01.22 um 10:40 schrieb Lucas De Marchi:
> On Fri, Jan 28, 2022 at 10:22:00AM +0100, Christian König wrote:
>> Am 28.01.22 um 10:12 schrieb Lucas De Marchi:
>>> On Fri, Jan 28, 2022 at 09:41:14AM +0100, Christian König wrote:
>>>> Rule #1 is to never ever break the build.
>>>>
>>>> Because of this all those patches needs to be squashed into a 
>>>> single one as far as I can see.
>>>
>>> what config are you building on?
>>
>> Well I'm not building at all, I'm just looking at the patches as an 
>> engineer with 25 years of experience with Linux patches.
>>
>> Just take a look at patch number 2:
>>
>> -static int fastrpc_vmap(struct dma_buf *dmabuf, struct dma_buf_map 
>> *map)
>> +static int fastrpc_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
>>
>> You are changing the functions signature without changing any of the 
>> callers.
>>
>> At bare minimum that causes a warning and on runtime this only works 
>> by coincident now because the structure pointers just happen to have 
>> the same layout. This is not something we usually do.
>
> you missed the magic/hack on patch 1:
>
> 1) dma-buf-map.h includes iosys-map.h _at the end_
> 2) iosys-map.h includes dma-buf-map.h at the beginning
>    and initially does a "define iosys_map dma_buf_map".
>
> So, it doesn't work by coincidence, It's because it was done to allow
> converting it piecemeal.

Oh, my. Please never do stuff like that again.

>
> But as I said, I don't really have a preference. When crossing
> subsystems one thing that is hard is that different people have different
> preferences on these things. At least squashing now is much easier than
> if I had to split it
>
> Try to imagine how much complain I received on going the other way in
> 25985edcedea6396277003854657b5f3cb31a628 with
> 2463 files changed, 4252 insertions(+), 4252 deletions(-)

Well exactly that is perfectly fine.

What you do here is applying your personal hack which is absolutely not 
welcomed.

Regards,
Christian.

> :)
>
>
> Lucas De Marchi
>
>>
>> Regards,
>> Christian.
>>
>>> I built this series, full config with
>>> CONFIG_COMPILE_TEST and doing:
>>>
>>>     git rebase -i <base> -x "make -j$(nproc)"
>>>
>>> I split these patches in a way that wouldn't break the build on 
>>> purpose.
>>> There were a couple that I couldn't build without cross compiling: 
>>> tegra
>>> and rockchip. The others were ok.
>>>
>>> I'm not really against squashing everything in one to merge, though.
>>> It will be hard on the conflicts later, but should get the job done 
>>> much
>>> quicker.
>>>
>>> Lucas De Marchi
>>>
>>>>
>>>> Regards,
>>>> Christian.
>>>>
>>>> Am 28.01.22 um 09:36 schrieb Lucas De Marchi:
>>>>> Motivation for this started in
>>>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F20220126203702.1784589-1-lucas.demarchi%40intel.com%2F&amp;data=04%7C01%7Cchristian.koenig%40amd.com%7C635084a520994d35a16e08d9e2423319%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637789596221829397%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=ruHpD3DbyyqQuZIFEQU%2B2RH31OwsdFnn1v7N4z75U0Y%3D&amp;reserved=0 
>>>>>
>>>>>
>>>>> when trying to extend the dma-buf-map API to cover new use cases: 
>>>>> help a
>>>>> single driver with allocations and sharing code paths for IO and 
>>>>> system
>>>>> memory. I'm leaving the API additions aside and first renaming the
>>>>> interface as requested.
>>>>>
>>>>> There are already some users in tree outside the context of dma-buf
>>>>> importer/exporter. So before extending the API, let's dissociate 
>>>>> it from
>>>>> dma-buf.
>>>>>
>>>>> The iosys-map.h is introduced in the first patch in a way that allows
>>>>> the conversion of each driver to happen separately. After all the
>>>>> conversions are done we can remove the old one, which is the last 
>>>>> patch.
>>>>> Another possible way is to squash everything and merge together,
>>>>> but I believe this would make much harder for review.
>>>>>
>>>>> The conversion was done with the following semantic patch:
>>>>>
>>>>>     @r1@
>>>>>     @@
>>>>>     - struct dma_buf_map
>>>>>     + struct iosys_map
>>>>>
>>>>>     @r2@
>>>>>     @@
>>>>>     (
>>>>>     - DMA_BUF_MAP_INIT_VADDR
>>>>>     + IOSYS_MAP_INIT_VADDR
>>>>>     |
>>>>>     - dma_buf_map_set_vaddr
>>>>>     + iosys_map_set_vaddr
>>>>>     |
>>>>>     - dma_buf_map_set_vaddr_iomem
>>>>>     + iosys_map_set_vaddr_iomem
>>>>>     |
>>>>>     - dma_buf_map_is_equal
>>>>>     + iosys_map_is_equal
>>>>>     |
>>>>>     - dma_buf_map_is_null
>>>>>     + iosys_map_is_null
>>>>>     |
>>>>>     - dma_buf_map_is_set
>>>>>     + iosys_map_is_set
>>>>>     |
>>>>>     - dma_buf_map_clear
>>>>>     + iosys_map_clear
>>>>>     |
>>>>>     - dma_buf_map_memcpy_to
>>>>>     + iosys_map_memcpy_to
>>>>>     |
>>>>>     - dma_buf_map_incr
>>>>>     + iosys_map_incr
>>>>>     )
>>>>>
>>>>>     @@
>>>>>     @@
>>>>>     - #include <linux/dma-buf-map.h>
>>>>>     + #include <linux/iosys-map.h>
>>>>>
>>>>> and then some files had their includes adjusted so we can build
>>>>> everything on each commit in this series. Also some comments were 
>>>>> update
>>>>> to remove mentions to dma-buf-map. Simply doing a sed to rename 
>>>>> didn't
>>>>> work as dma-buf has some APIs using the dma_buf_map prefix.
>>>>>
>>>>> Once finalized, I think most of this, if not all, could go through 
>>>>> the
>>>>> drm-misc-next branch. I split i915, msm, nouveau, and radeon in their
>>>>> own patches in case it's preferred to take those through their own
>>>>> trees.
>>>>>
>>>>> Lucas De Marchi
>>>>>
>>>>> Lucas De Marchi (14):
>>>>>   iosys-map: Introduce renamed dma-buf-map
>>>>>   misc: fastrpc: Replace dma-buf-map with iosys-map
>>>>>   dma-buf: Replace dma-buf-map with iosys-map
>>>>>   media: Replace dma-buf-map with iosys-map
>>>>>   drm/ttm: Replace dma-buf-map with iosys-map
>>>>>   drm: Replace dma-buf-map with iosys-map in drivers
>>>>>   drm/i915: Replace dma-buf-map with iosys-map
>>>>>   drm/msm: Replace dma-buf-map with iosys-map
>>>>>   drm/nouveau: Replace dma-buf-map with iosys-map
>>>>>   drm/tegra: Replace dma-buf-map with iosys-map
>>>>>   drm/radeon: Replace dma-buf-map with iosys-map
>>>>>   drm: Replace dma-buf-map with iosys-map in common code
>>>>>   Documentation: Refer to iosys-map instead of dma-buf-map
>>>>>   dma-buf-map: Remove API in favor of iosys-map
>>>>>
>>>>>  Documentation/driver-api/dma-buf.rst          |   4 +-
>>>>>  Documentation/gpu/todo.rst                    |  20 +-
>>>>>  MAINTAINERS                                   |   2 +-
>>>>>  drivers/dma-buf/dma-buf.c                     |  22 +-
>>>>>  drivers/dma-buf/heaps/cma_heap.c              |  10 +-
>>>>>  drivers/dma-buf/heaps/system_heap.c           |  10 +-
>>>>>  drivers/gpu/drm/ast/ast_drv.h                 |   2 +-
>>>>>  drivers/gpu/drm/ast/ast_mode.c                |   8 +-
>>>>>  drivers/gpu/drm/drm_cache.c                   |  18 +-
>>>>>  drivers/gpu/drm/drm_client.c                  |   9 +-
>>>>>  drivers/gpu/drm/drm_fb_helper.c               |  12 +-
>>>>>  drivers/gpu/drm/drm_gem.c                     |  12 +-
>>>>>  drivers/gpu/drm/drm_gem_cma_helper.c          |   9 +-
>>>>>  drivers/gpu/drm/drm_gem_framebuffer_helper.c  |  16 +-
>>>>>  drivers/gpu/drm/drm_gem_shmem_helper.c        |  15 +-
>>>>>  drivers/gpu/drm/drm_gem_ttm_helper.c          |   4 +-
>>>>>  drivers/gpu/drm/drm_gem_vram_helper.c         |  25 +-
>>>>>  drivers/gpu/drm/drm_internal.h                |   6 +-
>>>>>  drivers/gpu/drm/drm_mipi_dbi.c                |   8 +-
>>>>>  drivers/gpu/drm/drm_prime.c                   |   4 +-
>>>>>  drivers/gpu/drm/etnaviv/etnaviv_drv.h         |   2 +-
>>>>>  drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c   |   8 +-
>>>>>  drivers/gpu/drm/gud/gud_pipe.c                |   4 +-
>>>>>  drivers/gpu/drm/hyperv/hyperv_drm_modeset.c   |   5 +-
>>>>>  drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c    |   8 +-
>>>>>  .../drm/i915/gem/selftests/i915_gem_dmabuf.c  |   6 +-
>>>>>  .../gpu/drm/i915/gem/selftests/mock_dmabuf.c  |   6 +-
>>>>>  drivers/gpu/drm/lima/lima_gem.c               |   3 +-
>>>>>  drivers/gpu/drm/lima/lima_sched.c             |   4 +-
>>>>>  drivers/gpu/drm/mediatek/mtk_drm_gem.c        |   7 +-
>>>>>  drivers/gpu/drm/mediatek/mtk_drm_gem.h        |   5 +-
>>>>>  drivers/gpu/drm/mgag200/mgag200_mode.c        |   4 +-
>>>>>  drivers/gpu/drm/msm/msm_drv.h                 |   4 +-
>>>>>  drivers/gpu/drm/msm/msm_gem_prime.c           |   6 +-
>>>>>  drivers/gpu/drm/nouveau/nouveau_gem.c         |   2 +
>>>>>  drivers/gpu/drm/panfrost/panfrost_perfcnt.c   |  13 +-
>>>>>  drivers/gpu/drm/qxl/qxl_display.c             |   8 +-
>>>>>  drivers/gpu/drm/qxl/qxl_draw.c                |   6 +-
>>>>>  drivers/gpu/drm/qxl/qxl_drv.h                 |  10 +-
>>>>>  drivers/gpu/drm/qxl/qxl_object.c              |   8 +-
>>>>>  drivers/gpu/drm/qxl/qxl_object.h              |   4 +-
>>>>>  drivers/gpu/drm/qxl/qxl_prime.c               |   4 +-
>>>>>  drivers/gpu/drm/radeon/radeon_gem.c           |   1 +
>>>>>  drivers/gpu/drm/rockchip/rockchip_drm_gem.c   |   9 +-
>>>>>  drivers/gpu/drm/rockchip/rockchip_drm_gem.h   |   5 +-
>>>>>  drivers/gpu/drm/tegra/gem.c                   |  10 +-
>>>>>  drivers/gpu/drm/tiny/cirrus.c                 |   8 +-
>>>>>  drivers/gpu/drm/tiny/gm12u320.c               |   7 +-
>>>>>  drivers/gpu/drm/ttm/ttm_bo_util.c             |  16 +-
>>>>>  drivers/gpu/drm/ttm/ttm_resource.c            |  26 +-
>>>>>  drivers/gpu/drm/ttm/ttm_tt.c                  |   6 +-
>>>>>  drivers/gpu/drm/udl/udl_modeset.c             |   3 +-
>>>>>  drivers/gpu/drm/vboxvideo/vbox_mode.c         |   4 +-
>>>>>  drivers/gpu/drm/virtio/virtgpu_prime.c        |   1 +
>>>>>  drivers/gpu/drm/vkms/vkms_composer.c          |   4 +-
>>>>>  drivers/gpu/drm/vkms/vkms_drv.h               |   6 +-
>>>>>  drivers/gpu/drm/vkms/vkms_plane.c             |   2 +-
>>>>>  drivers/gpu/drm/vkms/vkms_writeback.c         |   2 +-
>>>>>  drivers/gpu/drm/xen/xen_drm_front_gem.c       |   7 +-
>>>>>  drivers/gpu/drm/xen/xen_drm_front_gem.h       |   6 +-
>>>>>  .../common/videobuf2/videobuf2-dma-contig.c   |   8 +-
>>>>>  .../media/common/videobuf2/videobuf2-dma-sg.c |   9 +-
>>>>>  .../common/videobuf2/videobuf2-vmalloc.c      |  11 +-
>>>>>  drivers/misc/fastrpc.c                        |   4 +-
>>>>>  include/drm/drm_cache.h                       |   6 +-
>>>>>  include/drm/drm_client.h                      |   7 +-
>>>>>  include/drm/drm_gem.h                         |   6 +-
>>>>>  include/drm/drm_gem_atomic_helper.h           |   6 +-
>>>>>  include/drm/drm_gem_cma_helper.h              |   6 +-
>>>>>  include/drm/drm_gem_framebuffer_helper.h      |   8 +-
>>>>>  include/drm/drm_gem_shmem_helper.h            |  12 +-
>>>>>  include/drm/drm_gem_ttm_helper.h              |   6 +-
>>>>>  include/drm/drm_gem_vram_helper.h             |   9 +-
>>>>>  include/drm/drm_prime.h                       |   6 +-
>>>>>  include/drm/ttm/ttm_bo_api.h                  |  10 +-
>>>>>  include/drm/ttm/ttm_kmap_iter.h               |  10 +-
>>>>>  include/drm/ttm/ttm_resource.h                |   6 +-
>>>>>  include/linux/dma-buf-map.h                   | 266 
>>>>> ------------------
>>>>>  include/linux/dma-buf.h                       |  12 +-
>>>>>  include/linux/iosys-map.h                     | 257 
>>>>> +++++++++++++++++
>>>>>  80 files changed, 579 insertions(+), 552 deletions(-)
>>>>>  delete mode 100644 include/linux/dma-buf-map.h
>>>>>  create mode 100644 include/linux/iosys-map.h
>>>>>
>>>>
>>