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Date:   Fri, 28 Jan 2022 01:40:18 -0800
From:   Lucas De Marchi <lucas.demarchi@intel.com>
To:     Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.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
Subject: Re: [PATCH 00/14] Rename dma-buf-map
Message-ID: <20220128094018.m7pixeznedoa47gb@ldmartin-desk2>
References: <20220128083626.3012259-1-lucas.demarchi@intel.com>
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On Fri, Jan 28, 2022 at 10:22:00AM +0100, Christian K?nig wrote:
>Am 28.01.22 um 10:12 schrieb Lucas De Marchi:
>>On Fri, Jan 28, 2022 at 09:41:14AM +0100, Christian K?nig 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.

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(-)
:)


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%7C15bd6767b2fb4b2c027e08d9e23e46af%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637789579371467295%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=yAllbKjW29SsXA0CMrhK%2BDDvZ1A5CrSptshmsh5vYNQ%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
>>>>
>>>
>