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axi_dmac: patch for partial transfers support 

This patch addresses the following issue:

  In case of transfers with multiple segments, if TLAST asserts on the last
beat of a non-last segment while more descriptors are queued up,
the completions for the queued segments may be missed causing timeout in
processes that wait for transfer completions.
main
Laszlo Nagy 2018-11-15 10:24:56 +00:00 committed by Laszlo Nagy
parent 5e1100ee77
commit 6fae37504b
1 changed files with 7 additions and 3 deletions
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10
library/axi_dmac/data_mover.v
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@ -136,7 +136,7 @@ generate if (ALLOW_ABORT == 1) begin
* A 'last' on the external interface indicates the end of an packet. If such a
* 'last' indicator is observed before the end of the current transfer stop
* accepting data on the external interface until a new descriptor is
* received that is the first segment of a transfer.
* received that is the first segment of a transfer.
*/
always @(posedge clk) begin
if (resetn == 1'b0) begin
@ -165,7 +165,7 @@ generate if (ALLOW_ABORT == 1) begin
assign rewind_req_valid = early_tlast;
assign rewind_req_data = {transfer_id,req_xlast_d,id_next};
// The width of the id must fit the number of transfers that can be in flight
// The width of the id must fit the number of transfers that can be in flight
// in the burst memory
always @(posedge clk) begin
if (resetn == 1'b0) begin
@ -196,8 +196,12 @@ end
// If we want to support zero delay between transfers we have to assert
// req_ready on the same cycle on which the last load happens.
// In case early tlast happens accept the new descriptor only when the rewind
// request got accepted.
assign last_load = m_axi_valid && last_eot && eot;
assign req_ready = last_load || ~active || (transfer_abort_s & rewind_req_ready);
assign req_ready = (last_load && ~early_tlast) ||
(~active && ~transfer_abort_s) ||
(transfer_abort_s && rewind_req_ready);
always @(posedge clk) begin
if (req_ready) begin