staging: xillybus: Removed outdated part in README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