On 20/03/2015 15:13, Daniel Vetter wrote:
On Thu, Mar 19, 2015 at 12:30:10PM +0000, John.C.Harrison@xxxxxxxxx wrote:
+void intel_ring_reserved_space_use(struct intel_ringbuffer *ringbuf, int size)
Just a bit of interface bikeshed - I'd drop the size parameter here. It
just duplicates what we tell the ring in the reservation code and the real
check happens in the _end function.
+{
+ WARN_ON(size > ringbuf->reserved_size);
+ WARN_ON(ringbuf->reserved_in_use);
+
+ ringbuf->reserved_in_use = true;
+ ringbuf->reserved_tail = ringbuf->tail;
+}
+
+void intel_ring_reserved_space_end(struct intel_ringbuffer *ringbuf)
+{
+ WARN_ON(!ringbuf->reserved_in_use);
+ WARN_ON(ringbuf->tail > ringbuf->reserved_tail + ringbuf->reserved_size);
Don't we need to handle wrap-around to make sure we do correctly check for
sufficient reservation?
-Daniel
There is nothing special to worry about for wrapping. The regular
intel_ring_begin() code will handle all that as before. The whole point
of the reserved scheme is that it is basically the same as calling
intel_ring_begin() with 'size + RESERVED_SIZE' everywhere. So when
i915_add_request() starts, it is guaranteed that an
'intel_ring_begin(RESERVED_SIZE)' has been done already including any
necessary buffer wrapping. Thus it does not actually need to call
'i_r_begin()' at all, really - it is guaranteed to succeed (as long as
it stays within RESERVED_SIZE total usage).
John.
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