net: ipa: support hard aggregation limits

Add a new flag for AP receive endpoints that indicates whether
a "hard limit" is used as a criterion for closing aggregation.
Add comments explaining the difference between "hard" and "soft"
aggregation limits.

Pass a flag to ipa_aggr_size_kb() so it computes the proper
aggregation size value whether using hard or soft limits.  Move
that function earlier in "ipa_endpoint.c" so it can be used
without a forward-reference.

Update ipa_endpoint_data_valid_one() so it validates endpoints whose
data indicate a hard aggregation limit is used, and so it reports
set aggregation flags for endpoints without aggregation enabled.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/net/ipa/ipa_endpoint.h b/drivers/net/ipa/ipa_endpoint.h
index 3ab62fb892ec..1e72a9695d3d 100644
--- a/drivers/net/ipa/ipa_endpoint.h
+++ b/drivers/net/ipa/ipa_endpoint.h
@@ -59,21 +59,32 @@ struct ipa_endpoint_tx {
  * struct ipa_endpoint_rx - Endpoint configuration for RX endpoints
  * @buffer_size:	requested receive buffer size (bytes)
  * @pad_align:		power-of-2 boundary to which packet payload is aligned
+ * @aggr_hard_limit:	whether aggregation closes before or after boundary
  * @aggr_close_eof:	whether aggregation closes on end-of-frame
  * @holb_drop:		whether to drop packets to avoid head-of-line blocking
  *
+ * The actual size of the receive buffer is rounded up if necessary
+ * to be a power-of-2 number of pages.
+ *
  * With each packet it transfers, the IPA hardware can perform certain
  * transformations of its packet data.  One of these is adding pad bytes
  * to the end of the packet data so the result ends on a power-of-2 boundary.
  *
  * It is also able to aggregate multiple packets into a single receive buffer.
  * Aggregation is "open" while a buffer is being filled, and "closes" when
- * certain criteria are met.  One of those criteria is the sender indicating
- * a "frame" consisting of several transfers has ended.
+ * certain criteria are met.
+ *
+ * Insufficient space available in the receive buffer can close aggregation.
+ * The aggregation byte limit defines the point (in units of 1024 bytes) in
+ * the buffer where aggregation closes.  With a "soft" aggregation limit,
+ * aggregation closes when a packet written to the buffer *crosses* that
+ * aggregation limit.  With a "hard" aggregation limit, aggregation will
+ * close *before* writing a packet that would cross that boundary.
  */
 struct ipa_endpoint_rx {
 	u32 buffer_size;
 	u32 pad_align;
+	bool aggr_hard_limit;
 	bool aggr_close_eof;
 	bool holb_drop;
 };