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io_ordering.txt: standardize document format 

Each text file under Documentation follows a different
format. Some doesn't even have titles!

Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:

- Add a title;
- mark literal-blocks as such.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
hifive-unleashed-5.1
Mauro Carvalho Chehab 2017-05-14 14:45:35 -03:00 committed by Jonathan Corbet
parent 9cf5116d5b
commit 0e95c85341
1 changed files with 33 additions and 29 deletions
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8
Documentation/io_ordering.txt
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@ -1,3 +1,7 @@
==============================================
Ordering I/O writes to memory-mapped addresses
==============================================
On some platforms, so-called memory-mapped I/O is weakly ordered. On such
platforms, driver writers are responsible for ensuring that I/O writes to
memory-mapped addresses on their device arrive in the order intended. This is
@ -8,7 +12,7 @@ critical section of code protected by spinlocks. This would ensure that
subsequent writes to I/O space arrived only after all prior writes (much like a
memory barrier op, mb(), only with respect to I/O).
A more concrete example from a hypothetical device driver:
A more concrete example from a hypothetical device driver::
...
CPU A: spin_lock_irqsave(&dev_lock, flags)
@ -25,7 +29,7 @@ CPU B: spin_unlock_irqrestore(&dev_lock, flags)
...
In the case above, the device may receive newval2 before it receives newval,
which could cause problems. Fixing it is easy enough though:
which could cause problems. Fixing it is easy enough though::
...
CPU A: spin_lock_irqsave(&dev_lock, flags)