From e502f9410313fb9ca7f68bb2a9d2d2d5106881c0 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Wed, 8 Aug 2018 11:30:27 +0200 Subject: [PATCH] ad_ip_jesd204_tpl_dac: hw.tcl: Choose lowest latency SAMPLES_PER_FRAME value For a specific set of L, M and NP framer configuration parameters there is an infinite set of possible values for the S and F configuration parameters as long as S and F are integer and the following relationship is met S / F = (L * 8) / (M * NP) Typically the preferred framer configuration is the one with the lowest latency. The lowest latency is achieved when S is minimal. Automatically compute and select this value for S instead of having the user to manually provide a value. Since some converters allow modes where S is not minimal provide a manual overwrite to specify S manually in case somebody wants to use such a mode. For completeness also add a read-only OCTETS_PER_FRAME (F) parameter that can be used to verify and check which value for F was chosen. There is no manual overwrite for F since if L, M, NP and S are set to a fixed value there is only a single possible value for F, which is computed automatically. Signed-off-by: Lars-Peter Clausen --- .../ad_ip_jesd204_tpl_dac_hw.tcl | 92 +++++++++++++++++++ 1 file changed, 92 insertions(+) diff --git a/library/jesd204/ad_ip_jesd204_tpl_dac/ad_ip_jesd204_tpl_dac_hw.tcl b/library/jesd204/ad_ip_jesd204_tpl_dac/ad_ip_jesd204_tpl_dac_hw.tcl index d87a3d490..0fef5124b 100644 --- a/library/jesd204/ad_ip_jesd204_tpl_dac/ad_ip_jesd204_tpl_dac_hw.tcl +++ b/library/jesd204/ad_ip_jesd204_tpl_dac/ad_ip_jesd204_tpl_dac_hw.tcl @@ -95,10 +95,32 @@ ad_ip_parameter CONVERTER_RESOLUTION INTEGER 16 true [list \ GROUP $group \ ] +ad_ip_parameter ENABLE_SAMPLES_PER_FRAME_MANUAL BOOLEAN 0 false [list \ + DISPLAY_NAME "Manual Samples per Frame" \ + GROUP $group \ +] + ad_ip_parameter SAMPLES_PER_FRAME INTEGER 1 true [list \ DISPLAY_NAME "Samples per Frame (S)" \ DISPLAY_UNITS "samples" \ ALLOWED_RANGES {1 2 3 4 6 8 12 16} \ + DERIVED true \ + GROUP $group \ +] + +ad_ip_parameter SAMPLES_PER_FRAME_MANUAL INTEGER 1 false [list \ + DISPLAY_NAME "Samples per Frame (S)" \ + DISPLAY_UNITS "samples" \ + ALLOWED_RANGES {1 2 3 4 6 8 12 16} \ + VISIBLE false \ + GROUP $group \ +] + +ad_ip_parameter OCTETS_PER_FRAME INTEGER 1 false [list \ + DISPLAY_NAME "Octets per Frame (F)" \ + DISPLAY_UNITS "octets" \ + ALLOWED_RANGES {1 2 4} \ + DERIVED true \ GROUP $group \ ] @@ -138,9 +160,79 @@ ad_ip_intf_s_axi s_axi_aclk s_axi_aresetn add_interface link_clk clock end add_interface_port link_clk link_clk clk Input 1 +# We don't expect too large values for a and b, trivial implementation will do +proc gcd {a b} { + if {$a == $b} { + return $b + } elseif {$a > $b} { + return [gcd [expr $a - $b] $b] + } else { + return [gcd $a [expr $b - $a]] + } +} + # validate proc p_ad_ip_jesd204_tpl_dac_validate {} { + set L [get_parameter_value "NUM_LANES"] + set M [get_parameter_value "NUM_CHANNELS"] + set NP [get_parameter_value "BITS_PER_SAMPLE"] + set N [get_parameter_value "CONVERTER_RESOLUTION"] + set S_manual [get_parameter_value "SAMPLES_PER_FRAME_MANUAL"] + set enable_S_manual [get_parameter_value "ENABLE_SAMPLES_PER_FRAME_MANUAL"] + + set channel_bus_width [expr 32 * $L / $M] + + # With fixed values for M, L and N' all valid values for S and F have a + # constant ratio of S / F. Choose a ratio so that S and F are co-prime. + # Choosing values for F and S that have a common factor has higher latency + # and no added benefits. + # + # Since converters often support those higher latency modes still allow a + # manual override of the S parameter in case somebody wants to use those modes + # anyway. + # + # To be able to set samples per frame manually ENABLE_SAMPLES_PER_FRAME_MANUAL + # needs to be set to true and SAMPLES_PER_FRAME_MANUAL to the desired value. + # + # When manual sample per frame selection is enabled still verify that the + # selected value is valid. + + set S_min [expr $L * 8] + set F_min [expr $M * $NP] + set common_factor [gcd $S_min $F_min] + set S_min [expr $S_min / $common_factor] + set F_min [expr $F_min / $common_factor] + + if {$enable_S_manual} { + foreach i {1 2 4} { + if {$F * $i <= 4 && $S * $i <= 16} { + lappend allowed_S [expr $S * $i] + } + } + + set_parameter_property SAMPLES_PER_FRAME_MANUAL ALLOWED_RANGES $allowed_S + + if {$S_manual % $S_min != 0} { + send_message ERROR "For framer configuration (L=$L, M=$M, NP=$NP) samples per frame (S) must be an integer multiple of $S_min" + set S $S_min + set F $F_min + } else { + set S $S_manual + set F [expr $S_manual * $M * $NP / $L / 8] + } + } else { + set_parameter_property SAMPLES_PER_FRAME_MANUAL ALLOWED_RANGES {1 2 3 4 6 8 12 16} + set S $S_min + set F $F_min + } + + set_parameter_value OCTETS_PER_FRAME $F + set_parameter_value SAMPLES_PER_FRAME $S + + set_parameter_property SAMPLES_PER_FRAME VISIBLE [expr !$enable_S_manual] + set_parameter_property SAMPLES_PER_FRAME_MANUAL VISIBLE $enable_S_manual + set data_path_enabled [expr ![get_parameter_value DATAPATH_DISABLE]] set cordic_enabled [expr $data_path_enabled && [get_parameter_value DDS_TYPE] == 1]