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| author | Maxime Ripard <maxime@cerno.tech> | 2021-03-16 11:06:23 +0300 |
|---|---|---|
| committer | Maxime Ripard <maxime@cerno.tech> | 2021-03-16 11:06:23 +0300 |
| commit | f8bade6c9a6213c2c5ba6e5bf32415ecab6e41e5 (patch) | |
| tree | 474c8fb8df9797b6e0d1e562b389f575c24afc50 /Documentation/gpu/todo.rst | |
| parent | ccf953d8f3d68e85e577e843fdcde8872b0a9769 (diff) | |
| parent | 51c3b916a4d7e24b4918925965867fdd9bd8dd59 (diff) | |
| download | linux-f8bade6c9a6213c2c5ba6e5bf32415ecab6e41e5.tar.xz | |
Merge drm/drm-next into drm-misc-next
Noralf needs some patches in 5.12-rc3, and we've been delaying the 5.12
merge due to the swap issue so it looks like a good time.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Diffstat (limited to 'Documentation/gpu/todo.rst')
| -rw-r--r-- | Documentation/gpu/todo.rst | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 62475d38c4ab..7ff9fac10d8b 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -571,6 +571,27 @@ Contact: Daniel Vetter Level: Intermediate +Remove automatic page mapping from dma-buf importing +---------------------------------------------------- + +When importing dma-bufs, the dma-buf and PRIME frameworks automatically map +imported pages into the importer's DMA area. drm_gem_prime_fd_to_handle() and +drm_gem_prime_handle_to_fd() require that importers call dma_buf_attach() +even if they never do actual device DMA, but only CPU access through +dma_buf_vmap(). This is a problem for USB devices, which do not support DMA +operations. + +To fix the issue, automatic page mappings should be removed from the +buffer-sharing code. Fixing this is a bit more involved, since the import/export +cache is also tied to &drm_gem_object.import_attach. Meanwhile we paper over +this problem for USB devices by fishing out the USB host controller device, as +long as that supports DMA. Otherwise importing can still needlessly fail. + +Contact: Thomas Zimmermann <tzimmermann@suse.de>, Daniel Vetter + +Level: Advanced + + Better Testing ============== @@ -644,7 +665,7 @@ for fbdev. https://patchwork.freedesktop.org/patch/306579/ - [RFC PATCH v2 00/13] Kernel based bootsplash - https://lkml.org/lkml/2017/12/13/764 + https://lore.kernel.org/r/20171213194755.3409-1-mstaudt@suse.de Contact: Sam Ravnborg |