staging: xillybus: Removed outdated part in README

The dedicated memory management routines have been replaced with devres API,
so the related part is removed from the doc.

Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eli Billauer 2014-07-17 17:53:20 +03:00 committed by Greg Kroah-Hartman
parent 84590b1aa9
commit 44909e658e
1 changed files with 0 additions and 23 deletions

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@ -26,7 +26,6 @@ Contents:
-- Data granularity -- Data granularity
-- Probing -- Probing
-- Buffer allocation -- Buffer allocation
-- Memory management
-- The "nonempty" message (supporting poll) -- The "nonempty" message (supporting poll)
@ -365,28 +364,6 @@ Or, if there already is a partially used page at hand, the buffer is packed
into that page. It can be shown that all pages requested from the kernel into that page. It can be shown that all pages requested from the kernel
(except possibly for the last) are 100% utilized this way. (except possibly for the last) are 100% utilized this way.
Memory management
-----------------
The tricky part about the buffer allocation procedure described above is
freeing and unmapping the buffers, in particular if something goes wrong in
the middle, and the allocations need to be rolled back. The three-stage
probing procedure makes this even more crucial, since temporary buffers are
set up and mapped in the first of its two stages.
To keep the code clean from complicated and bug-prone memory release routines,
there are special routines for allocating memory. For example, instead of
calling kzalloc, there's
void *xilly_malloc(struct xilly_cleanup *mem, size_t size)
which effectively allocates a zeroed buffer of size "size". Its first
argument, "mem", is where this allocation is enlisted, so that it's released
when xillybus_do_cleanup() is called with the same "mem" structure.
Two other functions enlist allocations in this structure: xilly_pagealloc()
for page allocations and xilly_map_single_*() for DMA mapping.
The "nonempty" message (supporting poll) The "nonempty" message (supporting poll)
--------------------------------------- ---------------------------------------