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authorMaxime Ripard <maxime@cerno.tech>2021-03-16 09:06:23 +0100
committerMaxime Ripard <maxime@cerno.tech>2021-03-16 09:06:23 +0100
commitf8bade6c9a6213c2c5ba6e5bf32415ecab6e41e5 (patch)
tree474c8fb8df9797b6e0d1e562b389f575c24afc50 /Documentation/gpu/todo.rst
parentccf953d8f3d68e85e577e843fdcde8872b0a9769 (diff)
parent51c3b916a4d7e24b4918925965867fdd9bd8dd59 (diff)
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')
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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