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Message-ID: <20220201003647.djakrmdebqigpz3j@ldmartin-desk2>
Date: Mon, 31 Jan 2022 16:36:47 -0800
From: Lucas De Marchi <lucas.demarchi@...el.com>
To: Christian König <christian.koenig@....com>
Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
srinivas.kandagatla@...aro.org, gregkh@...uxfoundation.org,
sumit.semwal@...aro.org, daniel.vetter@...ll.ch, airlied@...ux.ie,
lyude@...hat.com, tzimmermann@...e.de, linux-media@...r.kernel.org,
nouveau@...ts.freedesktop.org
Subject: Re: [PATCH 00/14] Rename dma-buf-map
On Fri, Jan 28, 2022 at 10:48:42AM +0100, Christian König wrote:
>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.
It's not uncommon approach to be required by other subsystems. Even
drm-intel already used similar approach for macro conversions crossing
drm-intel-next and drm-intel-gt-next branches recently. As I said, I
don't mind one way or the other.
Before I go and respin this into a single mega patch, I'd like to gather
some feedback on the following topics:
1) Daniel Vetter and Thomas Zimmermann seemed to be ok with staying with
the current name, dma_buf_map, while you prefer it renamed. Or at
least not make the rename a pre-requisite for the API additions in
https://lore.kernel.org/all/20220126203702.1784589-1-lucas.demarchi@intel.com/
One thing I like about the rename is that it makes clear the separation
between this small shim and dma-buf. There are also some APIs
that are really dma-buf API (e.g. dma_buf_map_attachment()), but if you
don't look carefully you may think it's from dma_buf_map.
2) If renaming, would it still keep the same entry in
MAINTAINERS? Thomas suggested drivers core, but this all seem to be used
mainly on drm/, with just one exception.
3) If renaming, do we have another preferred name?
thanks
Lucas De Marchi
>
>>
>>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&data=04%7C01%7Cchristian.koenig%40amd.com%7C635084a520994d35a16e08d9e2423319%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637789596221829397%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=ruHpD3DbyyqQuZIFEQU%2B2RH31OwsdFnn1v7N4z75U0Y%3D&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
>>>>>>
>>>>>
>>>
>
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