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| author | Will Deacon <will.deacon@arm.com> | 2019-02-22 16:17:54 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2019-04-08 12:00:45 +0100 |
| commit | 915530396c788d75c40f200edd67b56ac363c728 (patch) | |
| tree | 21ac21eddaa58d2479b08e0f75de3750ff14bc8d /Documentation/driver-api/pci | |
| parent | b012980d1c6e27f5c4adf0c19defca8658956820 (diff) | |
| download | linux-915530396c788d75c40f200edd67b56ac363c728.tar.gz linux-915530396c788d75c40f200edd67b56ac363c728.tar.bz2 linux-915530396c788d75c40f200edd67b56ac363c728.zip | |
Documentation: Kill all references to mmiowb()
The guarantees provided by mmiowb() are now provided implicitly by
spin_unlock(), so remove all references to this most confusing of
barriers from our Documentation.
Good riddance.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'Documentation/driver-api/pci')
| -rw-r--r-- | Documentation/driver-api/pci/p2pdma.rst | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/Documentation/driver-api/pci/p2pdma.rst b/Documentation/driver-api/pci/p2pdma.rst index 6d85b5a2598d..44deb52beeb4 100644 --- a/Documentation/driver-api/pci/p2pdma.rst +++ b/Documentation/driver-api/pci/p2pdma.rst @@ -132,10 +132,6 @@ precludes passing these pages to userspace. P2P memory is also technically IO memory but should never have any side effects behind it. Thus, the order of loads and stores should not be important and ioreadX(), iowriteX() and friends should not be necessary. -However, as the memory is not cache coherent, if access ever needs to -be protected by a spinlock then :c:func:`mmiowb()` must be used before -unlocking the lock. (See ACQUIRES VS I/O ACCESSES in -Documentation/memory-barriers.txt) P2P DMA Support Library |