From 5c300933609b5213322e271a4e745e2d4a101b31 Mon Sep 17 00:00:00 2001
From: Dan Callaghan <dcallagh@google.com>
Date: Thu, 10 Feb 2022 15:48:06 +1100
Subject: [PATCH] nexus: reduce OSCA worst case to 7%
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The current version of Crosslink-NX Family Data Sheet lists the high
frequency oscillator maximum frequency as 481.5MHz (that is, 7% higher
than its nominal 450MHz):

https://www.latticesemi.com/-/media/LatticeSemi/Documents/DataSheets/CrossLink/FPGA-DS-02049-1-2-1-CrossLink-NX-Family.ashx?document_id=52780

Older documents listed a wider frequency range but ±7% is the range for
production parts.
---
 nexus/pack.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/nexus/pack.cc b/nexus/pack.cc
index 5e9da304..81a729b1 100644
--- a/nexus/pack.cc
+++ b/nexus/pack.cc
@@ -1987,7 +1987,7 @@ struct NexusPacker
                     copy_constraint(ci, id_CLKI, id_CLKO, 1);
                 } else if (ci->type == id_OSC_CORE) {
                     int div = int_or_default(ci->params, ctx->id("HF_CLK_DIV"), 128);
-                    const float tol = 1.15f; // OSCA has +/-15% frequency tolerance, assume the worst case.
+                    const float tol = 1.07f; // OSCA has +/-7% frequency tolerance, assume the worst case.
                     set_period(ci, id_HFCLKOUT, delay_t((1.0e6 / 450) * (div + 1) / tol));
                     set_period(ci, id_LFCLKOUT, delay_t((1.0e3 / 10) / tol));
                 } else if (ci->type == id_PLL_CORE) {